Document:

LIMITED LIABILITY COMPANY AGREEMENT

                           OF PRIME REFRACTIVE, L.L.C.

     Organized under the Delaware Limited Liability Company Act (the "Act").

                                   ARTICLE I.

                                NAME AND LOCATION

     Section  1.1.  Name.  The name of this limited  liability  company is Prime
Refractive, L.L.C. (the "Company").

         Section  1.2.  Members.  The  only  members  of the  Company  upon  the
execution of this Limited Liability Company Agreement (this  "Agreement")  shall
be Prime Refractive  Management,  L.L.C., a Delaware limited  liability  company
("Prime  Management"),  and LASIK Investors L.L.C., a Delaware limited liability
company ("LASIK").  LASIK acknowledges and agrees that it initially owned all of
the outstanding  membership  interests of the Company and that Prime  Management
acquired its membership interest in the Company from LASIK. For purposes of this
Agreement,  the  "Members"  shall include such named members and any new members
admitted  pursuant  to the terms of this  Agreement,  but does not  include  any
person or entity who has ceased to be a member in the Company.

     Section 1.3. Principal Office. The principal office of the Company shall be
located in 1301 Capital of Texas Hwy., Suite C-300, Austin, Texas 78746-6550, or
such other location as may be selected by the Members.

     Section 1.4. Registered Agent and Address. The name of the registered agent
and the  address  of the  registered  office of the  Company as set forth in the
Certificate of Formation of the Company are:

                          The Corporation Trust Company
                          1209 Orange Street
                          Wilmington, Delaware 19801

     Section 1.5.  Other  Offices.  Other offices and other  facilities  for the
transaction of business shall be located at such places as the Managers may from
time to time determine.

         Section 1.6  Contribution  Agreement.  The Company was initially formed
with a single member, LASIK, in connection with the transactions contemplated by
that certain  Contribution  Agreement dated effective  September 1, 1999, by and
among Prime Medical  Operating,  Inc., a Delaware  corporation  ("PMOI"),  Prime
Medical Services,  Inc., a Delaware corporation ("PMSI"),  LASIK, Barnet Dulaney
Eye Center,  P.L.L.C.,  an Arizona  professional  limited liability company, the
Company, Prime Management,  Prime/BDEC  Acquisition,  L.L.C., a Delaware limited
liability company,  Prime/BDR Acquisition,  L.L.C., a Delaware limited liability
company,  David D. Dulaney, M.D., Ronald W. Barnet, M.D., and Mark Rosenberg (as
amended by that certain First  Amendment to  Contribution  Agreement dated as of
January 31, 2000, among the foregoing  parties,  the "Contribution  Agreement").
This agreement  supercedes and replaces any prior membership  agreement or other
governing or organizational document of the Company.

                                   ARTICLE II.

                                   MEMBERSHIP

     Section 2.1. Members' Interests.  The "Membership  Interest" of each Member
is set forth on Exhibit A.

     Section 2.2. Admission to Membership. The admission of new Members shall be
only by the unanimous  vote of the Members.  If new members are  admitted,  this
Agreement shall be amended to reflect each Member's revised Membership Interest.

     Section 2.3.  Property  Rights.  No Member shall have any right,  title, or
interest in any of the property or assets of the Company.

     Section  2.4.  Liability  of  Members.  No Member of the  Company  shall be
personally  liable for any debts,  liabilities,  or  obligations of the Company,
including under a judgment decree, or order of court.

         Section 2.5.  Transferability of Membership.  Except as provided below,
Membership  Interests in the Company are  transferable  only with the  unanimous
written  consent  of all  Members.  If such  unanimous  written  consent  is not
obtained when  required,  the  transferee  shall be entitled to receive only the
share of  profits  or other  compensation  by way of  income  and the  return of
contributions  to which  the  transferor  Member  otherwise  would be  entitled.
Notwithstanding the foregoing,  (i) the Membership Interests of Prime Management
may be freely transferred,  without consent, to any entity that is then owned or
controlled, directly or indirectly, by PMSI (or its successor in interest), (ii)
the  Membership  Interests  of any  Member  may be freely  assigned,  pledged or
otherwise  transferred,  without  consent,  to  secure  any debt,  liability  or
obligation owed to PMOI or its  subsidiaries  or affiliates by the Company,  any
Member or any entity affiliated with the Company, (iii) the Membership Interests
of any Member may be freely assigned, pledged or otherwise transferred,  without
consent, in favor of the Lender(s) under, or by the Lender(s) as a result of the
enforcement of any security  interest  arising  pursuant to, that certain Senior
Credit  Facility of PMSI (as  amended) or pursuant to that  certain  $14,000,000
Credit Facility of Prime Management (as amended),  (iv) the Membership Interests
of any Member may be freely  transferred,  without  consent,  pursuant to and in
accordance with the express terms and conditions of the Contribution  Agreement,
and (iv) the  pledge  by LASIK  (pursuant  to  Section  6.3 of the  Contribution
Agreement) of its right to receive  distributions from the Company in respect of
its  Membership  Interest  shall not be deemed to violate any  provision of this
Agreement..

         Section 2.6. Resignation of Members. A Member may not withdraw from the
Company except on the unanimous consent of the remaining  Members.  The terms of
the Members  withdrawal  shall be determined by agreement  between the remaining
Members and the withdrawing Member.

                                  ARTICLE III.

                                MEMBERS' MEETINGS

         Section  3.1.  Time and Place of Meeting.  All  meetings of the Members
shall be held at such  time and at such  place  within or  without  the State of
Delaware as shall be determined by the Managers.

         Section 3.2. Annual  Meetings.  In the absence of an earlier meeting at
such  time and place as the  Managers  shall  specify,  annual  meetings  of the
Members shall be held at the  principal  office of the Company on the date which
is thirty  (30) days after the end of the  Company's  fiscal year if not a legal
holiday,  and if a legal holiday,  then on the next full business day following,
at 10:00 a.m.,  at which  meeting the Members may transact  such business as may
properly be brought before the meeting.

     Section  3.3.  Special  Meetings.  Special  meetings  of the Members may be
called at any time by any Member.  Business transacted at special meetings shall
be confined to the purposes stated in the notice of the meeting.

         Section 3.4.  Notice.  Written or printed notice stating the place, day
and hour of any Members'  meeting,  and, in the case of a special  meeting,  the
purpose or purposes for which the meeting is called, shall be delivered not less
than ten (10) days nor more than thirty (30) days before the date of the special
meeting,  either  personally  or by mail,  by or at the  direction of the person
calling the meeting, to each Member entitled to vote at such meeting. If mailed,
such notice shall be deemed to be delivered three (3) days after it is deposited
in the United States mail,  postage prepaid,  to the Member at his address as it
appears on the records of the Company at the time of mailing.

         Section 3.5. Quorum. Members present in person or represented by proxy,
holding  more than fifty  percent  (50%) of the total votes which may be cast at
any meeting  shall  constitute  a quorum at all  meetings of the Members for the
transaction  of  business.  If,  however,  such  quorum  shall not be present or
represented at any meeting of the Members, the Members entitled to vote, present
in person or represented by proxy,  shall have power to adjourn the meeting from
time to time,  without notice other than  announcement  at the meeting,  until a
quorum shall be present or represented. When any adjourned meeting is reconvened
and a quorum shall be present or  represented,  any  business may be  transacted
which might have been  transacted at the meeting as originally  noticed.  Once a
quorum is constituted,  the Members present or represented by proxy at a meeting
may  continue  to  transact  business  until  adjournment,  notwithstanding  the
subsequent  withdrawal therefrom of such number of Members as to leave less than
a quorum.

         Section 3.6. Voting. When a quorum is present at any meeting,  the vote
of the Members, whether present or represented by proxy at such meeting, holding
more  than  fifty  percent  (50%) of the  total  votes  which may be cast at any
meeting shall be the act of the Members,  unless the vote of a different  number
is required by the Act, the  Certificate of Formation or this Limited  Liability
Company Agreement. Each Member shall be entitled to one vote for each percentage
point  represented by their  Membership  Interest.  Fractional  percentage point
interests shall be entitled to a corresponding fractional vote.

         Section  3.7.  Proxy.  Every  proxy must be  executed in writing by the
Member or by his duly authorized  attorney-in-fact,  and shall be filed with the
Secretary of the Company prior to or at the time of the meeting.  No proxy shall
be  valid  after  eleven  (11)  months  from the  date of its  execution  unless
otherwise  provided  therein.  Each proxy shall be  revocable  unless  expressly
provided therein to be irrevocable and unless otherwise made irrevocable by law.

         Section  3.8.  Action  by  Written  Consent.  Any  action  required  or
permitted  to be taken at any  meeting  of the  Members  may be taken  without a
meeting if a consent in  writing,  setting  forth the action so taken,  shall be
signed by all of the Members entitled to vote with respect to the subject matter
thereof,  and such  consent  shall have the same force and effect as a unanimous
vote of Members.

         Section 3.9. Meetings by Conference Telephone.  Members may participate
in and hold  meetings  of Members by means of  conference  telephone  or similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction  of any  business  on the ground  that the  meeting is not  lawfully
called or convened.

                                   ARTICLE IV.

                        MEMBERSHIP CAPITAL CONTRIBUTIONS

         Except  for  each  Member's  initial  capital   contribution   made  in
connection with the formation of the Company, no capital  contributions shall be
required  of any  Member  without  the  approval  of all the  Members  to  raise
additional capital, and only then proportionately as to each Member.

                                   ARTICLE V.

                             DISTRIBUTION TO MEMBERS

         The Company shall not  distribute (or allow to be  distributed)  to its
members,  with respect to their  respective  membership  interests,  any cash or
other  property  of the  Company  or its  subsidiaries  if,  at the  time of the
proposed   distribution,   any  amounts  (whether  principal  or  interest)  are
outstanding  under the Credit  Documents or the Target Center Lending  Documents
(as such terms are  defined in the  Contribution  Agreement).  Furthermore,  the
Company  shall  pay  all  available  cash  flow  in  payment  of  the  Company's
outstanding obligations,  if any, under the Working Capital Line and Development
Facility (as such terms are defined in the Contribution Agreement), irrespective
of whether such payments exceed the minimum required  payments under the Working
Capital Line and Development Facility.  For purposes of allocating such payments
among any two or more of such  outstanding  obligations,  such payments shall be
allocated  pro rata,  based upon the  respective  balances of such  obligations,
unless (i) a greater  portion of the  payment is  required  to be paid  toward a
given  obligation in order to prevent a default with respect to that  obligation
(but only to the extent  necessary  to prevent  such a default)  or (ii)  eighty
percent (80%) of the managers of the Company elect to allocate the payments in a
different manner.

         Notwithstanding  the foregoing,  as long as no party other than PMSI or
PMOI is in default  under the  Contribution  Agreement or any other  Transaction
Document (as defined in the Contribution Agreement, but excluding,  however, the
Credit Documents and the Target Center Lending  Documents),  then, to the extent
that (but only to the extent that) the Company possesses the cash flow necessary
(in  the  reasonable  discretion  of a  majority  of its  managers)  to pay  its
liabilities in the ordinary course  consistent with past practices,  the Company
agrees to make  quarterly  estimates  of its taxable  income for the current tax
year  and,  if not  prohibited  by law,  distribute  quarterly  (the  "Quarterly
Distributions")  an amount that would cover the federal and state  income  taxes
required to be paid by its members with respect  such taxable  income,  based on
each member's then current proportionate interest in the Company,  assuming that
all members pay income taxes on the Company's  taxable  earnings at a rate equal
to the highest  effective  individual  tax rate in effect from time to time (the
"Assumed Tax Rate");  provided,  further,  that the Company shall  determine its
actual  taxable  income at the end of each taxable year and (A) if the Quarterly
Distributions  in a given year should  have been  higher  based on the amount of
actual taxable income for that year,  promptly  distribute the amounts necessary
to eliminate such  deficiency or (B) if the Quarterly  Distributions  in a given
year  should have been lower  based on the amount of actual  taxable  income for
that  year,  withhold  dollar  for  dollar  from the first  following  Quarterly
Distribution,  and then against  subsequent  Quarterly  Distributions  in a like
manner, the amounts necessary to eliminate such surplus.

         Subject to the foregoing,  the Managers shall determine,  in their sole
discretion,  the  amount  and  timing  of all  distributions  from the  Company.
Distributions  shall be  divided  among the  Members  in  accordance  with their
Membership Interests. Distributions in kind shall be made on the basis of agreed
value  as  determined  by the  Members.  In no  event  may  the  Company  make a
distribution  to  its  Members  if,  immediately  after  giving  effect  to  the
distribution,  all  liabilities  of the Company,  other than  liabilities to the
Members with respect to their  interests and  liabilities for which the recourse
of creditors is limited to  specified  property of the Company,  exceed the fair
value of the  Company's  assets;  except that the fair value of property that is
subject to  liability  for which  recourse of  creditors  is  limited,  shall be
included  in the  Company  assets  only to the extent that the fair value of the
property  exceeds that  liability.  Except as contemplated in this Article V, no
distributions  of cash or  other  assets  of the  Company  shall  be made to the
Members in their capacity as owners of the Company.

                                   ARTICLE VI.

              ALLOCATION OF NET PROFITS AND LOSSES FOR TAX PURPOSES

         For  accounting  and income tax  purposes,  all items of income,  gain,
loss,  deduction,  and  credit of the  Company  for any  taxable  year  shall be
allocated  among the  Members in  accordance  with their  respective  Membership
Interests,  except as may be otherwise  required by the Internal Revenue Code of
1986, as amended.

                                  ARTICLE VII.

                           DISSOLUTION AND WINDING UP

     Section 7.1.  Dissolution.  Notwithstanding  any  provision of the Act, the
Company shall be dissolved only upon the first of the following to occur:

               (a) Forty (40) years from the date of filing the  Certificate  of
          Formation of the Company;

               (b)  Written   consent  of  all  the  then  current   Members  to
          dissolution;

                  (c) The  bankruptcy of a Member,  unless there is at least one
         remaining Member and such Member or, if more than one remaining Member,
         all remaining Members agree to continue the Company and its business.

         Section 7.2.  Winding Up.  Unless the Company is continued  pursuant to
Section 7.1(c) of this Article VII., in the event of dissolution of the Company,
the Managers (excluding any Manager(s) holding office pursuant to designation by
a Member subject to bankruptcy  proceedings) shall wind up the Company's affairs
as soon  as  reasonably  practicable.  On the  winding  up of the  Company,  the
Managers  shall pay and/or  transfer the assets of the Company in the  following
order:

               (a) In discharging liabilities (including loans from Members) and
          the expenses of concluding the Company's affairs; and

               (b) The balance,  if any, shall be divided between the Members in
          accordance with the Members' Membership Interests.

                                  ARTICLE VIII.

                                    MANAGERS

         Section 8.1. Selection of Managers.  Management of the Company shall be
vested in the  Managers.  Initially,  the Company  shall have five (5) Managers,
being Ken  Shifrin,  Teena  Belcik,  and Brad  Hummel,  (as the initial  Manager
designees of Prime  Management),  David D. Dulaney,  M.D., and Ronald W. Barnet,
M.D. (as the initial  Manager  designees of LASIK).  Thereafter,  for so long as
there are five (5) Managers, (a) Prime Management shall be entitled to designate
three (3) of the  Managers;  and (b) LASIK shall be entitled  to  designate  the
remaining two (2) of the Managers. Notwithstanding the foregoing, a Member shall
not be entitled to designate any Manager unless its Membership Interest: (x) has
not  (other  than  as  allowed  under  Section  2.5  of  this   Agreement)  been
transferred,   repurchased,  assigned,  pledged,  hypothecated  or  in  any  way
alienated;  and (y)  equals or  exceeds  forty  percent  (40%) of the  aggregate
Membership  Interests;  provided,  however,  that if the  immediately  preceding
subsection  (y) shall apply to LASIK  solely  because of an exercise by LASIK of
its put rights  under  Section  9.8 of the  Contribution  Agreement,  then LASIK
shall,  unless  and  until  there is an  additional  decrease  in it  Membership
Interest other than pursuant to Section 9.8 of the  Contribution  Agreement,  be
entitled to designate only one Manager in the manner provided above. The Members
may, by unanimous vote of all Members,  from time to time,  change the number of
Managers of the Company and remove or add Managers accordingly.  A Manager shall
serve as a Manager until their resignation or removal pursuant to Section 8.2 or
8.3 of this  Article  VIII.  Managers  need  not be  residents  of the  State of
Delaware or Members of the Company.

         Section 8.2. Resignations.  Each Manager shall have the right to resign
at any time upon  written  notice of such  resignation  to the  Members.  Unless
otherwise  specified in such written notice,  the resignation  shall take effect
upon the  receipt  thereof,  and  acceptance  of such  resignation  shall not be
necessary to make same effective.  The Member who designated a resigning manager
shall be entitled to designate  the  successor  thereto and all Members agree to
take such action as may be necessary to cause the election of all such successor
Managers.

         Section 8.3.  Removal of Managers.  Any Manager may be removed,  for or
without cause,  at any time, but only by the Member who designated such Manager,
upon the written notice to all Members.  The Member who designated  such removed
Manager  shall be entitled to designate  the  successor  thereto and all Members
agree to take such action as may be  necessary to cause the election of all such
successor Managers.

         Section  8.4.  General  Powers.  The  business of the Company  shall be
managed by its Managers, which may, by the vote or written consent in accordance
with this  Agreement,  exercise any and all powers of the Company and do any and
all such  lawful  acts and  things  as are not by the Act,  the  Certificate  of
Formation or this Limited Liability Company Agreement directed or required to be
exercised or done by the Members, including, but not limited to, contracting for
or incurring on behalf of the Company debts,  liabilities and other obligations,
without the consent of any other person, except as otherwise provided herein.

     Section 8.5. Place of Meetings.  The Managers of the Company may hold their
meetings,  both  regular  and  special,  either  within or without  the State of
Delaware.

         Section 8.6. Annual Meetings.  The annual meeting of the Managers shall
be held without further notice  immediately  following the annual meeting of the
Members, and at the same place, unless by unanimous consent of the Managers that
such time or place shall be changed.

     Section 8.7. Regular Meetings. Regular meetings of the Managers may be held
without  notice at such time and place as shall from time to time be  determined
by the Managers.

     Section  8.8.  Special  Meetings.  Special  meetings  of the Mangers may be
called by any Manager on seven (7) days notice to each Manager, with such notice
to be given personally, by mail or by telecopy, telegraph or mailgram.

         Section  8.9.  Quorum and Voting.  At all  meetings of the Managers the
presence of at least four (4) Managers  shall be  necessary  and  sufficient  to
constitute a quorum for the transaction of business, and the affirmative vote of
at least a majority of the  Managers  present at any meeting at which there is a
quorum shall be the act of the Managers, except as may be otherwise specifically
provided by the Act, the Contribution Agreement, the Certificate of Formation or
this Agreement. If a quorum shall not be present at any meeting of Managers, the
Managers  present there may adjourn the meeting from time to time without notice
other  than  announcement  at the  meeting,  until a quorum  shall  be  present.
Notwithstanding any voting, quorum, or other provisions of this Agreement to the
contrary,  the affirmative  vote of at least four (4) Managers shall be required
to effect any of the following actions:

               (a) any amendment, modification or waiver of any provision of the
          Company's Certificate of Formation or this Agreement;

               (b) effecting any mergers,  consolidations or combinations of the
          Company with other entities;

               (c)  dissolving,  liquidating,  or filing  bankruptcy  or seeking
          relief under any debtor relief law;

               (d) entering into a transaction  or other action with a Member or
          Manager;

                  (e) borrowing or incurring any  indebtedness,  other than open
         accounts  payable  to  unaffiliated  third  parties,  or  granting  any
         collateral  or  security  (by way of  guaranty  or  otherwise)  for any
         indebtedness or obligation,  that exceeds (in any single transaction or
         directly related series of transactions) $25,000;

                  (f) purchasing or leasing assets or property, or entering into
         any  contract  or  obligation,  which  obligates  the Company to pay in
         excess  of  $25,000  in  one  or  any   directly   related   series  of
         installments;

               (g) selling, leasing or otherwise transferring  substantially all
          of the  Company's  assets  other  than in the  ordinary  course of the
          Company's business;

                  (h)  except  as  expressly  set forth in  Section  9.12 of the
         Contribution Agreement, allocating to the Company any costs or expenses
         that are paid or  incurred by any Member or its  affiliates  (excluding
         the Company),  or paid by the Company but reimbursable by any Member or
         its affiliates (excluding the Company), in each instance;

               (i) issuance of any ownership interest in the Company; and

                  (j)  disposition,  sale,  assignment or other  transfer by the
         Company  of any  interest  it owns in the  Company,  except  that  such
         interest may be extinguished  without the approval  required under this
         Section.

         Section 8.10.  Committees.  The Managers  may, by resolution  passed by
eighty percent (80%) of the Managers,  designate  committees,  each committee to
consist  of two or more  Managers  (at  least  one of  which  must be a  Manager
designee  of Prime  Management  and one of which must be a Manager  designee  of
LASIK),  which  committees shall have such power and authority and shall perform
such  functions  as may be  provided  in  such  resolution.  Such  committee  or
committees  shall have such name or names as may be  designated  by the Managers
and shall keep regular  minutes of their  proceedings and report the same to the
Managers when required.

         Section  8.11.  Compensation  of Managers.  The Members  shall have the
authority  to  provide,  by  unanimous  approval,  that  any  one or more of the
Managers  shall not be  compensated,  and may, by  unanimous  approval,  fix any
compensation  (which may include  expenses) they elect to pay to any one or more
of the Managers.

         Section  8.12.  Action by  Written  Consent.  Any  action  required  or
permitted  to be  taken  at any  meeting  of the  Managers  or of any  committee
designated  by the Managers may be taken  without a meeting if written  consent,
setting  forth the  action so taken,  is signed by all the  Managers  or of such
committee,  and such consent shall have the same force and effect as a unanimous
vote at a meeting.

         Section 8.13. Meetings by Conference Telephone.  Managers or members of
any committee  designated by the Managers may  participate in and hold a meeting
of the Managers or such  committee by means of  conference  telephone or similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction  of any  business  on the ground  that the  meeting is not  lawfully
called or convened.

     Section  8.14.  Liability of Managers.  No Manager of the Company  shall be
personally  liable for any debts,  liabilities,  or  obligations of the Company,
including under a judgment, decree, or order of the court.

         Section 8.15.  Specific Power of Managers.  The Managers shall have the
authority to enter into and execute all  documents in relation to the  formation
of the Company  including,  but not limited to,  issuance of the  Certificate of
Formation and this Limited Liability Company Agreement.

                                   ARTICLE IX.

                                     NOTICES

         Section 9.1. Form of Notice.  Whenever under the provisions of the Act,
the Certificate of Formation or this Limited  Liability Company Agreement notice
is required to be given to any Manager or Member, and no provision is made as to
how such notice shall be given,  notice shall not be construed to mean  personal
notice only, but any such notice may also be given in writing,  by mail, postage
prepaid,  addressed  to such Manager or Member at such address as appears on the
books of the Company, or by telecopy, telegraph or mailgram. Any notice required
or  permitted  to be given by mail  shall be deemed  to be given  three (3) days
after it is deposited, postage prepaid, in the United States mail as aforesaid.

         Section 9.2. Waiver. Whenever any notice is required to be given to any
Manager or Member of the Company under the provision of the Act, the Certificate
of Formation or this Limited  Liability Company  Agreement,  a waiver thereof in
writing signed by the person or persons entitled to such notice,  whether signed
before or after the time stated in such waiver,  shall be deemed  equivalent  to
the giving of such notice.

                                   ARTICLE X.

                                    OFFICERS

         Any Manager may also serve as an officer of the  Company.  The Managers
may  designate  one or more persons who are not Managers of the Company to serve
as officers and may designate the titles of all officers.  The initial  officers
of the Company shall be: Ken Shifrin,  Chairman of the Board; Joe Jenkins, M.D.,
President;  Cheryl  Williams,  Vice  President,  Secretary  and Chief  Financial
Officer;  and Mark Rosenberg,  Vice President.  Unless  otherwise  provided in a
resolution of the Members or Managers the officers of the Company shall have the
powers  designated  with  respect to such  offices  under the  Delaware  Limited
Liability Company Act, and any successor statute, as amended from time-to-time.

                                   ARTICLE XI.

                                    INDEMNITY

         Section 11.1.  Indemnification.  The Company shall indemnify any person
who was or is a party or is  threatened  to be made a party  to any  threatened,
pending or  completed  action,  suit or  proceeding,  whether  civil,  criminal,
administrative, arbitrative or investigative, any appeal in such an action, suit
or  proceeding  and any  inquiry  or  investigation  that  could lead to such an
action,  suit or proceeding  (whether or not by or in the right of the Company),
by reason of the fact that such person is or was a manager, officer, employee or
agent of the  Company or is or was  serving at the  request of the  Company as a
director,  manager, officer, partner, venturer,  proprietor,  trustee, employee,
agent or similar  functionary  of another  corporation,  employee  benefit plan,
other enterprise,  or other entity, against all judgments,  penalties (including
excise and similar taxes), fines, settlements and reasonable expenses (including
attorneys'  fees and court  costs)  actually and  reasonably  incurred by him in
connection with such action,  suit or proceeding to the fullest extent permitted
by any  applicable  law,  and such  indemnity  shall inure to the benefit of the
heirs,  executors and administrators of any such person so indemnified  pursuant
to this Article XI. The right to indemnification  under this Article XI shall be
a contract  right and shall not be deemed  exclusive of any other right to which
those seeking  indemnification may be entitled under any law, bylaw,  agreement,
vote of members or disinterested managers or otherwise, both as to action in his
official  capacity  and as to action in  another  capacity  while  holding  such
office. Any repeal or amendment of this Article XI by the Members of the Company
or by changes in  applicable  law shall,  to the extent  permitted by applicable
law, be prospective only, and shall not adversely affect the  indemnification of
any person who may be indemnified at the time of such repeal or amendment.

         Section   11.2.   Indemnification   Not   Exclusive.   The   rights  of
indemnification  and reimbursement  provided for in this Article XI shall not be
deemed  exclusive  of any  other  rights  to which  any such  Manager,  officer,
employee or agent may be  entitled  under the  Certificate  of  Formation,  this
Limited  Liability  Company  Agreement,  agreement  or vote of Members,  or as a
matter of law or otherwise.

         Section  11.3.  Other  Indemnification  Clauses.   Notwithstanding  the
foregoing,   this  Article  XI  shall  not  be  construed  to   contradict   the
indemnification   provision  of  the  Contribution  Agreement.   Notwithstanding
anything  contained  herein,  this Article XI shall be ineffectual and shall not
permit or require  indemnification for all, or any, losses, costs,  liabilities,
claims or expenses arising, directly or indirectly,  from any action or omission
permitting or requiring indemnification under the Contribution Agreement; and in
no event may any  indemnity be allowed  under this  Agreement or pursuant to any
provision   of  the  Act  for  an  amount  paid  or  payable   pursuant  to  the
indemnification provisions of the Contribution Agreement.

                                  ARTICLE XII.

                                  MISCELLANEOUS

     Section 12.1. Fiscal Year. The fiscal year of the Company shall be fixed by
resolution of the Managers.

     Section 12.2.  Records.  At the expense of the Company,  the Managers shall
maintain  records and accounts of all  operations of the Company.  At a minimum,
the Company shall keep at its principal place of business the following records:

               (a) A current list of the name and last known mailing  address of
          each Member;

               (b) A current list of each Member's Membership Interest;

               (c) A copy of the Certificate of Formation and Limited  Liability
          Company Agreement of the Company, and all amendments thereto, together
          with executed copies of any powers of attorney;

               (d) Copies of the  Federal,  state,  and local income tax returns
          and reports for the Company's six most recent tax years; and

               (e)  Correct  and  complete  books and  records of account of the
          Company.

         Section 12.3. Seal. The Company may by resolution of the Managers adopt
and have a seal, and said seal may be used by causing it or a facsimile  thereof
to be  impressed  or  affixed or in any manner  reproduced.  Any  officer of the
Company shall have authority to affix the seal to any document requiring it.

     Section 12.4. Agents.  Every Manager and Officer is an agent of the Company
for the purpose of the business. The act of a Manager or Officer,  including the
execution  in the name of the Company of any  instrument  for carrying on in the
usual way the business of the Company, binds the Company.

         Section 12.5. Checks. All checks,  drafts and orders for the payment of
money,  notes  and other  evidences  of  indebtedness  issued in the name of the
Company  shall be  signed  by such  officer,  officers,  agent or  agents of the
Company  and in such  manner  as  shall  from  time to  time  be  determined  by
resolution of the Managers. In the absence of such determination by the Mangers,
such  instruments  shall  be  signed  by  the  Treasurer  or the  Secretary  and
countersigned  by the  President  or a Vice  President  of the  Company,  if the
Company has such officers.

     Section 12.6.  Deposits.  All funds of the Company shall be deposited  from
time to time to the credit of the  Company in such  banks,  trust  companies  or
other depositories as the Managers may select.

         Section  12.7.  Annual  Statement.  The Managers  shall present at each
annual  meeting,  and,  when called for by vote of the  Members,  at any special
meeting of the Members, a full and clear statement of the business and condition
of the Company.

         Section 12.8.  Financial  Statements.  As soon as practicable after the
end of each fiscal year of the  Company,  a balance  sheet as at the end of such
fiscal year,  and a profit and loss  statement  for the period  ended,  shall be
distributed  to the  Members,  along with such tax  information  (including  all
information  returns) as may be necessary for the  preparation of each Member of
its Federal,  state and local income tax returns.  The balance  sheet and profit
and loss statement  referred to in the previous  sentence may be as shown on the
Company's federal income tax return.

         Section 12.9. Binding Arbitration.  Any controversy between the parties
regarding  this  Agreement and any claims  arising out of this  Agreement or its
breach  shall be submitted  to  arbitration  by either  party.  The  arbitration
proceedings shall be conducted by a single arbitrator pursuant to the Commercial
Arbitration Rules of the American Arbitration Association. The arbitration shall
be conducted in Dallas,  Texas and the arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

                                  ARTICLE XIII.

                                   AMENDMENTS

         Section 13.1.  Amendments.  This  Agreement may be altered,  amended or
repealed and a new limited liability  company agreement may be adopted,  only in
accordance  with the  provisions  of Section 8.9,  but  otherwise at any regular
meeting or at any special meeting called for that purpose,  or by execution of a
written consent in accordance with the provisions of Section 3.8.

         Section 13.2. When Limited  Liability  Company  Agreement Silent. It is
expressly recognized that when the Limited Liability Company Agreement is silent
or in conflict with the  requirements  of the Act as to the manner of performing
any Company function, the provisions of the Act shall control.

                            [Signature page follows]

<PAGE>

                                SIGNATURE PAGE TO

                       LIMITED LIABILITY COMPANY AGREEMENT

         IN WITNESS WHEREOF,  the undersigned  Members hereby adopt this Limited
Liability  Company  Agreement as the Limited  Liability Company Agreement of the
Company, effective as of the 1st day of September, 1999.

                                           LASIK Investors, L.L.C.

                                           By: /s/ Ronald W. Barnet, M.D.
                                                 Ronald W. Barnet, M.D., manager

                                           By: /s/ David D. Dulaney, M.D.
                                                 David D. Dulaney, M.D., manager

                                           Prime Refractive Management, L.L.C.

                                           By: /s/ Cheryl Williams

                                           Printed Name: Cheryl Williams
                                           Title: Chief Financial Officer

<PAGE>
                                    EXHIBIT A

                               OWNERSHIP INTERESTS

Name                                                       Ownership Percentage

Prime Management                                                 60%

LASIK                                                            40%STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the  "Company") and Bradley J. Wojcik and Holly M.
Wojcik, individuals residing in Granite Bay, California, and shareholders of the
Company (individually and collectively referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 16,487 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-10 and C-57 (collectively, including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $187,010.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Bradley J. and Holly M. Wojcik
                                8605 Woodrock Way
                                Granite Bay, California   95746

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:  /s/ Bradley J. Wojcik

                              Printed Name: Bradley J. Wojcik

                              Signature:  /s/ Holly M. Wojcik

                              Printed Name:  Holly M. Wojcik

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the  "Company") and BT Alex Brown,
Inc.,  Custodian  for the  benefit of Stephen  G.  Turner,  Rollover - IRA dated
February 10, 1997, a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  97,628 authorized  and issued shares of the  Company's $0.01 par
value common stock presently owned by Seller and evidenced by stock certificate
number C-58 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be $1,614,863.00 (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         BT Alex Brown, Inc., Custodian for the benefit
                                of Stephen G. Turner, Roth - IRA
                                dated February 10, 1997
                                Seneca Capital Management
                                909 Montgomery Street, #500
                                San Francisco, California   94133

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ BT Alex Brown c/4
                                         Stephen G. Turner IRA
                                         E. Darlene Lewis, POA VP

                              Printed Name: E. Darlene Lewis

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada corporation (the "Company") and K.J. Townsend and
E.  Townsend,  Trustees  under  The  Townsend  Trust  dated  Ausgust  30,  1995,
individuals residing in Roseville,  California,  and shareholders of the Company
("collectively and indivually referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 13,987 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-8 (collectively,  including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $158,652.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         K.J. Townsend and E. Townsend, Trustees
                                The Townsend Trust dated August 30, 1995
                                7281 Acorn Glenn Loop
                                Roseville, California   95747-8156

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>
         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:/s/ K.J. Townsend

                              Printed Name: K.J. Townsend, Trustee under The
                                            Townsend Trust dated August 30, 1995

Company:                      Horizon Vision Center, Inc.

                                    By:/s/ David P. Bates III

                                    Printed Name:  David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada corporation (the "Company") and Beatrice Sandler,
Trustee  under the  Beatrice  Sandler  Trust,  and  shareholder  of the  Company
(collectively referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 25,000 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-12 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $283,571.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Beatrice Sandler
                                Trustee, Beatrice Sandler Trust
                                18607 Aceituno Street
                                San Diego, California   92128

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>
         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Beatrice Sandler

                              Printed Name:  Beatrice Sandler
                                             Trustee, Beatrice Sandler Trust

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada corporation (the "Company") and James Douglas Reed, an individual
residing in Folsom, California, and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,763 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-73 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,997.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         James Douglas Reed
                                157 Cascade Falls Drive
                                Folsom, California   95630

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

S-2

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ James Douglas Reed

                              Printed Name: James Douglas Reed

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc.,  a Nevada  corporation  (the  "Company")  and  Elizabeth  Jeane  Reed,  an
individual  residing in Folsom,  California,  and a  shareholder  of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,763 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-74 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,997.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Elizabeth Jean Reed
                                157 Cascade Falls Drive
                                Folsom, California   95630

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>
         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:  /s/ Elizabeth  Jeane  Reed
                              Printed Name: Elizabeth  Jeane  Reed

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc.,  a Nevada  corporation  (the  "Company")  and Panda  Investments,  LLC,  a
shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 16,458 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-11 and C-54 (collectively, including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $186,681.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Panda Investments, LLC
                                P.O. Box 560
                                Carmichael, California   95609-0560

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Panda  Investments,  LLC by OR
                                             (per authorization of Trustees)

                              Printed Name: Panda  Investments,  LLC
                                            Omer Rains

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name:David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By:/s/ Cheryl Williams
                                   Cheryl Williams, Vice President

<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc.,  a Nevada  corporation  (the  "Company")  and Carter Nice,  an  individual
residing in Sacramento, California and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 15,000 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-7 and C-53 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $170,143.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Carter Nice
                                7729 Rio Barco Way
                                Sacramento, California   95831

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Carter Nice

                              Printed Name: Carter Nice

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the  "Company") and C.G. Neff,  Jr., an individual
residing in Zephyr Cove, Nevada and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  5,000 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-6 (collectively,  including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $56,714.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         C.G. Neff, Jr.
                                600 Highway 50, Pinewild Unit 127
                                Zephyr Cove, Nevada   89448

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ C.G. Neff,  Jr.

                              Printed Name: C.G. Neff,  Jr.

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name:  David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Frank T. Moormand and Luthera R.
Moorman,  individuals  residing in Sacramento,  California,  shareholders of the
Company (collectively and individually referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 16,438 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-5 and C-52 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $186,454.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Frank T. or Luthera R. Moorman
                                3324 Club Lane
                                Sacramento, California   95821

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Frank T. Moormand

                              Printed Name: Frank T. Moormand

                              Signature: /s/ Luthera R. Moormand

                              Printed Name: Luthera R. Moormand

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada corporation (the "Company") and Kenneth V. Miselis, an individual
residing in Stockton, California and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 27,811 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-15 (collectively, including such shares of common stock, the "Capital Stock").
The  purchase  price for the  Capital  Stock shall be  $315,456  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Kenneth V. Miselis, M.D.
                                5762 Acorn Court
                                Stockton, California  95212

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Kenneth V. Miselis, M.D.

                              Printed Name: Kenneth V. Miselis, M.D.

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the  "Company")  and Wayne L. Marsh and Barbara K.
Koerner,  individuals  residing in Sacramento,  California,  shareholders of the
Company (collectively and individually referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  14,030 authorized  and issued shares of the  Company's $0.01 par
value common stock presently owned by Seller and evidenced by stock certificate
number C-9 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be $159,140.00 (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Wayne L. Marsh and Barbara K. Koener
                                2840 Echo Way
                                Sacramento, California   95821

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Wayne L. Marsh

                              Printed Name: Wayne L. Marsh

                              Signature: /s/ Barbara K. Koerne

                              Printed Name: Barbara K. Koerne

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title:President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center, Inc., a Nevada corporation (the "Company") and Sandra E. and Mark
R. Mandel, Trustees under Trust Agreement dated April 12, 1989, and shareholders
of the Company (collectively and individually referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  13,942 authorized  and issued shares of the  Company's $0.01 par
value common stock presently owned by Seller and evidenced by stock certificate
number C-20 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be $158,142.00 (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Sandra E. Mandel and Mark R. Mandel
                                Trustees under Trust Agreement dated
                                April 12, 1989
                                680 Brewer Road
                                Hillsborough, California   94010

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Sandra E. Mandel

                              Printed Name: Sandra E. Mandel, Trustees under
                                           Trust Agreement dated April 12, 1989

                              Signature: /s/ Mark R. Mandel

                              Printed Name:Mark R. Mandel, Trustees under
                                           Trust Agreement dated April 12, 1989

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

         This Stock Purchase  Agreement (this "Agreement") is entered into to be
effective   as  of  September 1, 1999 (the "Effective Time"), among PrimeSight,
L.L.C., a Delaware limited liability company ("Prime"), Horizon Vision Center,
Inc.,  a  Nevada  corporation (the "Company") and Scott B. Lee, an individual
residing in Winters, California, and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  14,000 authorized  and issued shares of the  Company's $0.01 par
value common stock presently owned by Seller and evidenced by stock certificate
number C-4 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be $158,800.00 (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Scott B. Lee
                                26090 Country Road 34
                                Winters, California   95694

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

S-2

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Scott B. Lee

                              Printed Name: Scott B. Lee

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By:/s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the "Company") and Jill G. Kennedy,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 14,352 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-14 and C-89 (collectively, including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $162,793.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Jill G. Kennedy
                                1385 Yale Avenue
                                Salt Lake City, Utah   84105

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Jill G. Kennedy

                              Printed Name: Jill G. Kennedy

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada corporation (the "Company") and Laura G. Kennedy,  an individual
residing in Farmington, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-79 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Laura G. Kennedy
                                465 W. Honey Bee Circle
                                Farmington, Utah   84025

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:/s/ Laura G. Kennedy

                              Printed Name: Laura G. Kennedy

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada corporation (the "Company") and John Paul Kennedy,  an individual
residing in Farmington, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-80 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         John Paul Kennedy
                                465 W. Honey Bee Circle
                                Farmington, Utah   84025

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ John Paul Kennedy

                              Printed Name: John Paul Kennedy

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center, Inc., a Nevada corporation (the "Company") and Robert P. Kennedy,
an individual  residing in  Farmington,  Utah and a  shareholder  of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-81 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Robert P. Kennedy
                                465 W. Honey Bee Circle
                                Farmington, Utah   84025

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Laura Kennedy

                              Printed Name: Laura Kennedy, Parent Guardian for
                                Robert P. Kennedy, a Minor, Age 1 Year

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation (the "Company") and Robert J. Hardy,
M.D.,  Inc.,  Profit  Sharing  Plan and  Trust,  a  shareholder  of the  Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 25,000 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-3 (collectively,  including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $283,571.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         [INSERT SELLER'S ADDRESS]

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Robert J. Hardy, M.D.

                               Printed Name: Robert J. Hardy, M.D., Trustee,
                                Robert J. Hardy, M.D.,  Inc.,  Profit  Sharing
                                Plan and  Trust

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the "Company") and David S. Grodin,  an individual
residing in San Leandro, California and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  7,576 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-61 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $85,933.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         David S. Grodin
                                15134 Andover Street
                                San Leandro, California    94579

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ David S. Grodin

                              Printed Name: David S. Grodin

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition  L.L.C., a Delaware limited  liability  company  ("Prime"),  Horizon
Vision  Center,  Inc., a Nevada  corporation  (the  "Company") and John Benjamin
Griffin,  an individual residing in Provo, Utah and a shareholder of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-99 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         John Benjamin Griffin
                                3018 North Comanche Lane
                                Provo, Utah   84604

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:/s/John R. Griffin

                              Printed Name: John R. Griffin, Parent Guardian for
                                     John Benjamin Griffin, A Minor, Age 1 week

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name:  David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition  L.L.C., a Delaware limited  liability  company  ("Prime"),  Horizon
Vision Center, Inc., a Nevada corporation (the "Company") and Katherine Griffin,
an  individual  residing  in  Provo,  Utah  and a  shareholder  of  the  Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-78 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Katherine Griffin
                                1110 East 300 South
                                Provo, Utah   84606

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ John R. Griffin

                              Printed Name: John R. Griffin, Parent Guardian for
                                        Katherine Griffin, a Minor, Age 3 Years

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and John R. Griffin,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-75 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         John R. Griffin
                                3018 North Comanche Lane
                                Provo, Utah   84604

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ John R. Griffin

                              Printed Name: John R. Griffin

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Jill C. Griffin,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-76 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Jill C. Griffin
                                3018 North Comanche Lane
                                Provo, Utah   84604

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>
         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Jill C. Griffin

                              Printed Name: Jill C. Griffin

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and David M. Griffin,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-84 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         David M. Griffin
                                1110 East 300 South
                                Provo, Utah   84606

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ David M. Griffin

                              Printed Name: David M. Griffin

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Craig S. Griffin,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-87 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Craig S. Griffin
                                c/o John R. Griffin
                                3018 North Comanche Lane
                                Provo, Utah   84604

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Craig S. Griffin

                              Printed Name: Craig S. Griffin

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Craig S. Griffin,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-87 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Craig S. Griffin
                                c/o John R. Griffin
                                3018 North Comanche Lane
                                Provo, Utah   84604

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.
Seller:                       Signature: /s/ Craig S. Griffin

                              Printed Name: Craig S. Griffin

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Jolie M. Griffin,  an individual
residing in Coralville, Iowa and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-83 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Jolie M. Griffin
                                2315 Mulberry Street, #4
                                Coralville, Iowa   52241

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Jolie M. Griffin

                               Printed Name: Jolie M. Griffin

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation (the "Company") and Jasmine Griffin,
an  individual  residing  in  Provo,  Utah  and a  shareholder  of  the  Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized  and issued shares of the  Company's $0.01 par
value common stock presently owned by Seller and evidenced by stock certificate
number C-77 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be $19,986.00 (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Jasmine Griffin
                                1110 East 300 South
                                Provo, Utah   84606

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ John R. Griffin

                              Printed Name: John R. Griffin, Parent Guardian for
                                Jasmine Griffin, a Minor, Age 5 Years

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition  L.L.C., a Delaware limited  liability  company  ("Prime"),  Horizon
Vision  Center,  Inc.,  a Nevada  corporation  (the  "Company")  and Benjamin R.
Griffin,  an individual residing in Provo, Utah and a shareholder of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-86 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Benjamin Griffin
                                1110 E. 300 South
                                Provo, Utah   84606

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/  David M. Griffin

                             Printed Name: David M. Griffin, Parent Guardian for
                                Benjamin R.Griffin, A Minor, Age 1 Year

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada corporation (the "Company") and Rebekah S. Griffin, an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-85 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Rebekah S. Griffin
                                1110 East 300 South
                                Provo, Utah   84606

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Rebekah S. Griffin

                              Printed Name: Rebekah S. Griffin

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name:Rebekah S. Griffin

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision  Center,  Inc.,  a Nevada  corporation  (the  "Company")  and the Griffin
Charitable Remainder Trust, a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 39,951 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-92 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $453,158.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         J. Robert Griffin, Trustee under the
                                Griffin Charitable Remainder
                                4913 Puma Way
                                Carmichael, California   95608

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>
         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/  J. Robert Griffin, Trustee

                              Printed Name: J. Robert Griffin, Trustee under the
                                        Griffin Charitable Remainder Trust

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center, Inc., a Nevada corporation (the "Company") and J. Robert Griffin,
Trustee under the Griffin & Reed, a Medical Corporation,  401 (k) Profit Sharing
Plan, a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 65,819 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-2 and C-50 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $746,576.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         J. Robert Griffin, Trustee under the
                                Griffin & Reed, a Medical Corporation,
                                401(k) Profit Sharing Plan
                                651 Fulton Avenue
                                Sacramento, California   95825

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/  J. Robert Griffin, Trustee

                              Printed Name: J. Robert Griffin, Trustee under the
                                        Griffin & Reed, A Medical Corporation,
                                        401(k) Profit Sharing Plan

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Michael Rex Favero,  D.M.D.,  an
individual  residing in Sacramento,  California and a shareholder of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 25,000 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-1 (collectively,  including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $283,571.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Michael Rex Favero, D.M.D.
                                2237 Park Towne Circle
                                Sacramento, California   95825

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:/s/ Michael Rex Favero,  D.M.D.

                              Printed Name: Michael Rex Favero,  D.M.D.

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the "Company") and Joyce C. Elhard,  an individual
residing  in  Mokelumne  Hill,  California  and a  shareholder  of  the  Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 11,363 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-62 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $128,889.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Joyce C. Elhard
                                18998 Penny Way
                                Mokelumne Hill, California   95245

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/  Joyce C. Elhard

                              Printed Name:  Joyce C. Elhard

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the  "Company") and Donna L. Davis,  an individual
residing in Hayward, California and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 30,518 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-48 and C-68 (collectively, including such shares of common stock, the "Capital
Stock").  The  purchase  price for the  Capital  Stock  shall be  $346,161  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                     1301 Capital of Texas Highway
                           Suite C-300
                           Austin, Texas  78746
                           Attention:  President

with a copy to:            Mr. Timothy L. LaFrey
                           Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                           816 Congress Avenue, Suite 1900
                           Austin, Texas  78701

Company:                   Horizon Vision Centers, Inc.
                           14895 East 14th Street, Suite 400
                           San Leandro, California   94578

Seller:                    Donna L. Davis
                           27336 Greenhaven Road
                           Hayward, California   94542-1440

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

S-2

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Donna L. Davis

                               Printed Name: Donna L. Davis

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc.,  a Nevada  corporation  (the  "Company")  and  David B.  Davis,  M.D.,  an
individual  residing in Hayward,  California  and a  shareholder  of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 30,517 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-49 and C-67 (collectively, including such shares of common stock, the "Capital
Stock").  The  purchase  price for the  Capital  Stock  shall be  $346,150  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                     1301 Capital of Texas Highway
                           Suite C-300
                           Austin, Texas  78746
                           Attention:  President

with a copy to:            Mr. Timothy L. LaFrey
                           Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                           816 Congress Avenue, Suite 1900
                           Austin, Texas  78701

Company:                   Horizon Vision Centers, Inc.
                           14895 East 14th Street, Suite 400
                           San Leandro, California   94578

Seller:                    David B. Davis II, M.D.
                           1237 B Street
                           Hayward, CA   94541-2915

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ David B.  Davis,  M.D.

                              Printed Name: David B.  Davis,  M.D.

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of September  1,  1999(the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc.,  a  Nevada  corporation  (the  "Company")  and  Kristine  C.  Clemens,  an
individual  residing in San Ramon,  California  and a shareholder of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  8,983 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-21 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $101,893.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                     1301 Capital of Texas Highway
                           Suite C-300
                           Austin, Texas  78746
                           Attention:  President

with a copy to:            Mr. Timothy L. LaFrey
                           Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                           816 Congress Avenue, Suite 1900
                           Austin, Texas  78701

Company:                   Horizon Vision Centers, Inc.
                           14895 East 14th Street, Suite 400
                           San Leandro, California   94578

Seller:                    Kristine C. Clemens
                           134 Enchanted Way
                           San Ramon, California   94583

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Kristine  C.  Clemens

                              Printed Name: Kristine  C.  Clemens

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and The Corporation of the President
of the Church of Jesus Christ of Latter-Day  Saints, a Utah Corporation Sole, in
Salt Lake City, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  2,115 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-88 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $23,990.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which it is a party; and

                  (c)  deliver   such  good   standing   certificates,   officer
certificates,  and similar  documents and certificates as counsel for Seller may
reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                              1301 Capital of Texas Highway
                                    Suite C-300
                                    Austin, Texas  78746
                                    Attention:  President

with a copy to:                     Mr. Timothy L. LaFrey
                                    Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                    816 Congress Avenue, Suite 1900
                                    Austin, Texas  78701

Company:                            Horizon Vision Centers, Inc.
                                    14895 East 14th Street, Suite 400
                                    San Leandro, California   94578

Seller:                             The Corporation of the President
                                    of the Church of Jesus Christ
                                    of Latter-Day Saints,
                                    a Utah Corporation Sole
                                    c/o Jill G. Kennedy
                                    1385 Yale Avenue
                                    Salt Lake City, Utah   84105

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Ray Anderson
                              Printed Name:  Ray Anderson, authorized agent

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President

                       [Signature page for Prime follows]

<PAGE>

Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.

                           --------------------------

                                       and

                           Horizon Vision Center, Inc.

                              --------------------

                             Dated September 1, 1999

<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the "Company") and David P. Bates,
III and Jane A.  Bates,  individuals  residing  in San  Ramon,  California,  and
shareholders  of the  Company  (collectively  and  individually  referred  to as
"Seller").

The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
22,663  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock  certificate  number C-26
and C-47 (collectively, the "Capital Stock"). The purchase price for the Capital
Stock shall be $257,063.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

            Representations and Warranties of the Company and Seller

         Seller and the Company hereby  represent and warrant to Prime,  jointly
and  severally,  that each of the  following  matters is true and correct in all
respects as of the Closing  Date (with the  understanding  that Prime is relying
materially  on each  such  representation  and  warranty  in  entering  into and
performing this Agreement),  which  representations and warranties shall also be
deemed  made as of the  Effective  Time and which  shall  survive  the  Closing;
provided,  however,  that all  representations  and  warranties  made by  Seller
hereunder shall be deemed made by Seller only to the actual knowledge of Seller.

         3.1 Due  Organization.  The Company is a  corporation  duly  organized,
validly existing, and in good standing under the laws of the State of Nevada and
has full power and  authority to carry on its business as now  conducted  and as
proposed to be conducted. The Company is qualified to do business and is in good
standing  in the states set forth on  Schedule  3.1(a)  attached  hereto,  which
states represent every jurisdiction where such qualification is required for the
conduct of the Company's business as conducted on the Closing Date. Complete and
correct copies of the Company's Articles of Incorporation,  Bylaws, all board of
directors'  resolutions,  all  shareholders'  resolutions,  and  all  amendments
thereto,  have been  delivered to Prime.  Schedule  3.1(b) sets forth a true and
complete  list,  as of the Closing  Date, of all of the holders of any equity or
other ownership interest in the Company or of any right to obtain, by conversion
or otherwise,  and regardless of whether  presently  exercisable,  any equity or
other  ownership  interest in the  Company;  in each case showing the number and
type of interest  or right held.  Schedule  3.1(b) also  identifies  each of the
persons  listed   therein  that  is  a  physician  or  other  licensed   medical
professional,  and describes  each such  person's  license(s)  and  professional
title. Except as set forth on Schedule 3.1(b),  immediately prior to the Closing
Date there are outstanding (i) no shares of equity or other voting securities of
the Company,  (ii) no securities of the Company convertible into or exchangeable
for shares of equity or other voting securities of the Company, (iii) no options
or other rights to acquire from the Company or Seller,  and no obligation of the
Company or Seller to issue or sell, any equity or other voting securities of the
Company or any securities of the Company  convertible  into or exchangeable  for
such equity or voting securities,  and (iv) no equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar  rights of or with respect to the Company.  Immediately  following
the Closing of this transaction and the closings of the Related Acquisitions (as
hereinafter  defined),  Prime will own sixty  percent (60%) of all of the voting
equity  securities of the Company (after  assuming the  conversion,  exchange or
exercise of any and all securities or rights  convertible  into, or exchangeable
or exercisable for, voting equity  securities of the Company),  and all of those
persons and entities listed on Schedule 3.1(b) will own, in the aggregate, forty
percent  (40%) of all of the voting  equity  securities  of the  Company  (after
assuming  the  conversion,  exchange or exercise  of any and all  securities  or
rights  convertible  into, or  exchangeable  or exercisable  for,  voting equity
securities of the Company).  The Capital Stock transferred by Seller to Prime at
the Closing,  as well as all other capital stock of the Company  transferred  to
Prime in the Related Acquisitions,  will be duly authorized,  validly issued and
outstanding,  fully  paid,  non-assessable,  and free of any  liens,  claims  or
encumbrances whatsoever.

         3.2  Subsidiaries.  Except as set  forth on  Schedule  3.2  (reflecting
ownership  interests  and the nature of such  interests),  the Company  does not
directly or indirectly  have (or possess any options or other rights to acquire)
any  subsidiaries or any direct or indirect  ownership  interests in any person,
business,  corporation,  partnership,  limited liability  company,  association,
joint venture, trust, or other entity.

         3.3 Due  Authorization.  Each of the  Company and Seller has full power
and  authority to enter into and perform  this  Agreement  and each  Transaction
Document  required  to be  executed  by the  Company  or  Seller  in  connection
herewith.  The execution,  delivery,  and performance of this Agreement and each
such  Transaction  Document has been duly authorized by all necessary  action of
the Company,  its directors,  its officers and its shareholders.  This Agreement
and each such  Transaction  Document  has been  duly and  validly  executed  and
delivered  by the  Company  and  Seller  and  constitutes  a valid  and  binding
obligation  of the  Company  and  Seller,  enforceable  against  each of them in
accordance  with its terms.  The execution,  delivery,  and  performance of this
Agreement,  and each  Transaction  Document  required  herein to be  executed by
Seller  and/or the Company do not (a) violate any  federal,  state,  county,  or
local law,  rule,  or  regulation  applicable  to the Company,  the Business (as
hereinafter defined),  the Company's assets or the Capital Stock, (b) violate or
conflict with, or permit the cancellation of, any agreement to which the Company
is a party,  or by which the Company or its properties  are bound,  or result in
the creation of any lien, security interest,  charge, or encumbrance upon any of
such  properties or the upon the Capital Stock,  (c) permit the  acceleration of
the maturity of any  indebtedness of Seller or the Company,  or any indebtedness
secured by the Capital  Stock or by the property of the Company,  or (d) violate
or conflict with any provision of the  organizational  documents of the Company.
No action,  consent,  waiver or approval of, or filing with, any federal, state,
county or local  governmental  authority is required by Seller or the Company in
connection  with the execution,  delivery,  or performance of this Agreement (or
any Transaction Document).

         3.4  Financial  Statements.  The  unaudited  balance  sheet and  income
statement  of the  Company as of and for each of the years  ended March 31, 1998
and 1999, and the unaudited balance sheet and income statement of the Company as
of and for  the  three  (3)  months  ended  June  30,  1999  (collectively,  the
"Financial  Statements")  are  attached  hereto  as  Exhibit  A.  The  Financial
Statements have been prepared in accordance with generally  accepted  accounting
principles  consistently  applied ("GAAP") (except as specifically noted therein
or in Schedule  3.4) and fairly  present the  financial  position and results of
operations  of the  Company  as of the  indicated  dates  and for the  indicated
periods.  Except for liabilities  incurred in the ordinary course of business or
disclosed  in  Schedule  3.4,  and except to the extent  specifically  and fully
reflected in the Financial Statements  (including the notes thereto),  as of the
Closing Date, the Company has no claims,  debts,  liabilities,  or  obligations,
whether known or unknown, absolute,  contingent or otherwise (including, but not
limited to,  federal,  state,  and local taxes,  any sales taxes,  use taxes and
property  taxes,  any taxes arising from the  transactions  contemplated by this
Agreement and any liabilities arising from any litigation or civil,  criminal or
regulatory  proceeding  involving or related to the  Company,  its assets or the
Business).  The  Company and Seller each agree to  indemnify  and hold  harmless
Prime  and its  affiliates  from and  against  any and all such  claims,  debts,
liabilities and obligations.  Except as set forth in Schedule 3.4 hereto,  since
June 30,  1999 there has been no  material  adverse  change in the assets of the
Company, the Business, or the results of operations or financial position of the
Company.

         3.5 Conduct of Business;  Certain Actions.  As used herein,  "Business"
means all of the business  conducted  by the  Company,  which shall be deemed to
include  all  refractive  surgery  modalities,  now  performed,  offered or made
available, including, without limitation,  implantable contact lenses, instromal
corneal  rings,  laser  in  situs  keratomileusis  photorefractive  keratectomy,
automated lemellar  keratoplasty,  radial keratotomy,  astigmatic keratotomy and
similar procedures.  Except as set forth on Schedule 3.5 attached hereto,  since
June 30, 1999,  the Company has  conducted  its Business and  operations  of the
Business in the ordinary  course and consistent  with its past practices and has
not (a)  purchased  or retired  any  indebtedness,  or  purchased,  retired,  or
redeemed any  ownership  interest  from,  any  director,  officer,  shareholder,
employee or affiliate of the Company,  or engaged in any other  transaction that
involves or requires  distributions of money or other assets from the Company to
any director, officer, shareholder, employee or affiliate of the Company if such
other  transaction  is not done in the  ordinary  course of business  and is not
consistent with past practices of the Company, (b) increased the compensation of
any  directors,  officers,  employees,  agents,  contractors,  vendors  or other
parties,  except for wage and salary  increases  made in the ordinary  course of
business and consistent with the past practices of the Company, (c) made capital
expenditures  exceeding  $10,000  individually or $25,000 in the aggregate,  (d)
sold any asset (or any group of related assets) in any transaction (or series of
related  transactions)  in which the purchase price or book value for such asset
(or group of related assets) exceeded  $10,000,  (e) discharged or satisfied any
lien or encumbrance or paid any obligation or liability, absolute or contingent,
other than  current  liabilities  incurred  and paid in the  ordinary  course of
business,  (f) made or guaranteed any loans or advances to any party whatsoever,
(g) suffered or permitted any lien, security interest,  claim,  charge, or other
encumbrance to arise or be granted or created against or upon any of its assets,
real or personal,  tangible or intangible, (h) canceled, waived, or released any
of its  debts,  rights,  or  claims  against  third  parties,  (i)  amended  its
organizational  documents, (j) made or paid any severance or termination payment
to any director, officer, employee, agent, contractor, vendor or consultant, (k)
made any  change  in its  method  of  accounting,  (l) made  any  investment  or
commitment  therefor  in  any  person,   business,   corporation,   association,
partnership,  limited liability company, joint venture,  trust, or other entity,
(m) made, entered into, amended, or terminated any written employment  contract,
created,  made,  amended,  or  terminated  any  bonus,  stock  option,  pension,
retirement,  profit sharing,  or other employee benefit plan or arrangement,  or
withdrawn  from any  "multi-employer  plan" (as defined in the Internal  Revenue
Code of 1986, as amended (the "Code")) so as to create any liability under ERISA
(as  hereinafter  defined) to any person or entity,  (n) amended,  terminated or
experienced a termination of any material contract, agreement, lease, franchise,
or license  to which it is a party,  (o) made any  distributions,  in cash or in
kind, to its  shareholders,  or to any person or entity related to or affiliated
therewith,  in any  capacity,  except  such  distributions  as are  made  in the
ordinary course of the Company's  business  consistent with past practices,  (p)
entered into any other material  transactions  except in the ordinary  course of
business, (q) entered into any contract, commitment, agreement, or understanding
to do any acts described in the foregoing  clauses (a)-(p) of this Section,  (r)
suffered any material  damage,  destruction,  or loss (whether or not covered by
insurance) to any assets,  (s) experienced any strike,  slowdown,  or demand for
recognition by a labor  organization by or with respect to any of its employees,
or (t)  experienced  or effected any  shutdown,  slow-down,  or cessation of any
operations conducted by, or constituting part of, it.

         3.6 Assets;  Licenses,  Permits,  etc.  Except as set forth on Schedule
3.6(a), the Company has good and marketable title to all of its assets, free and
clear  of  all  liens,  security  interests,  claims,  rights  of  another,  and
encumbrances  of any kind  whatsoever.  The  assets of the  Company  are in good
operating  condition and repair,  subject to ordinary wear and tear, taking into
account the  respective  ages of the  properties  involved  and are all that are
necessary for the conduct of the Business. Attached hereto as Schedule 3.6(b) is
a list and description of all federal,  state,  county,  and local  governmental
licenses,  certificates,  certificates of need,  permits,  waivers,  filings and
orders  held or applied  for by the Company and used or relied on (or to be used
or relied on) in  connection  with the  Business  ("Permits").  The  Company has
complied  in all  material  respects,  and the Company is in  compliance  in all
material  respects,  with the  terms  and  conditions  of any such  Permits.  No
additional  Permit  is  required  from  any  federal,  state,  county,  or local
governmental  agency or body  thereof  in  connection  with the  conduct  of the
Business.  No claim has been made by any  governmental  authority  (and,  to the
knowledge of Seller and the Company,  no such claim has been  threatened) to the
effect that a Permit not possessed by the Company is necessary in respect of the
Business.

         3.7      Environmental Issues.

                  (a) For purposes of this  Agreement,  the term  "environmental
laws"  shall  mean  all  laws  and  regulations  relating  to  the  manufacture,
processing,  distribution,  use, treatment,  storage,  disposal,  transport,  or
handling, or the emission, discharge, or release, of any pollutant, contaminant,
chemical,  or industrial  toxic or hazardous  substance or waste,  and any order
related thereto.

                  (b) The Company has complied in all material respects with and
obtained  all  authorizations  and made all filings  required by all  applicable
environmental laws. The properties occupied or used by the Company have not been
contaminated with any hazardous wastes, hazardous substances, or other hazardous
or toxic  materials  in  violation  of any  applicable  environmental  law,  the
violation of which could have a material  adverse  impact on the Business or the
financial position of the Company.

                  (c) The  Company has not  received  any notice from the United
States  Environmental  Protection  Agency that it is a  potentially  responsible
party under the Comprehensive Environmental Response, Compensation and Liability
Act  ("Superfund  Notice"),  any  citation  from  any  federal,  state  or local
governmental  authority for non-compliance with its requirements with respect to
air, water or environmental pollution, or the improper storage, use or discharge
of any  hazardous  waste,  other  waste or  other  substance  or other  material
pertaining to its business  ("Citations") or any written notice from any private
party alleging any such  non-compliance;  and there are no pending or unresolved
Superfund  Notices,  Citations or written notices from private parties  alleging
any such non-compliance.

         3.8  Intellectual  Property Rights.  There are no patents,  trademarks,
trade names, or copyrights, and no applications therefor, owned by or registered
in the name of the Company or in which the Company  has any right,  license,  or
interest.  The  Company  is not a party  to any  license  agreement,  either  as
licensor or licensee, with respect to any patents,  trademarks,  trade names, or
copyrights.  The Company has not received any notice that it is  infringing  any
patent, trademark, trade name, or copyright of others.

         3.9  Compliance  with Laws. To the knowledge of the Company and Seller,
the  Company  has  complied  in all  material  respects,  and the  Company is in
compliance in all material respects,  with all federal, state, county, and local
laws, rules,  regulations and ordinances  currently in effect. No claim has been
made or  threatened  by any  governmental  authority  against the Company to the
effect that the business conducted by the Company fails to comply in any respect
with any law, rule, regulation, or ordinance.

         3.10  Insurance.  Attached  hereto  as  Schedule  3.10 is a list of all
policies of fire, liability, business interruption, and other forms of insurance
(including,  without  limitation,  professional  liability  insurance)  and  all
fidelity  bonds held by or applicable to the Company at any time within the past
three (3) years,  which  schedule  sets forth in respect of each such policy the
policy name, policy number,  carrier, term, type of coverage,  deductible amount
or self-insured retention amount, limits of coverage, and annual premium. To the
knowledge of the Company and Seller,  no event directly  relating to the Company
has occurred  which will result in a retroactive  upward  adjustment of premiums
under any such policies or which is likely to result in any  prospective  upward
adjustment in such premiums.  There have been no material changes in the type of
insurance  coverage  maintained by the Company  during the past three (3) years,
including without  limitation any change which has resulted in any period during
which the Company had no insurance coverage.  Excluding insurance policies which
have  expired and been  replaced,  no  insurance  policy of the Company has been
canceled  within  the last three (3) years and no threat has been made to cancel
any insurance policy of the Company within such period.

         3.11 Employee  Benefit  Matters.  Except as set forth on Schedule 3.11,
the  Company  does not  maintain  nor does it  contribute  nor is it required to
contribute to any "employee welfare benefit plan" (as defined in section 3(1) of
the  Employee  Retirement  Income  Security Act of 1974 (and any sections of the
Code amended by it) and all regulations promulgated thereunder, as the same have
from time to time been amended ("ERISA")) or any "employee pension benefit plan"
(as defined in ERISA).  The Company  does not  presently  maintain and has never
maintained,  or had any  obligation of any nature to  contribute  to, a "defined
benefit plan" within the meaning of the Code.

         3.12 Contracts and  Agreements.  Attached  hereto as Schedule 3.12 is a
list of all written or oral contracts, commitments, leases, and other agreements
(including, without limitation, all promissory notes, loan agreements, and other
evidences  of  indebtedness,  mortgages,  deeds of trust,  security  agreements,
pledge agreements,  service  agreements,  and similar agreements and instruments
and all confidentiality  agreements) to which the Company is a party or by which
the  Company or its  properties  are bound,  pursuant  to which the  obligations
thereunder of any party thereto are, or are contemplated as being, in respect of
any such individual contracts,  commitments,  leases, or other agreements during
any year during the term  thereof,  $25,000 or greater,  or which are  otherwise
material to the Business  (collectively  the  "Contracts"  and  individually,  a
"Contract").  The Company is not and, to the best  knowledge  of the Company and
Seller,  no other party thereto is in default (and no event has occurred  which,
with the passage of time or the giving of notice,  or both,  would  constitute a
default by the Company or, to the best  knowledge of the Company and Seller,  by
any other  party  thereto)  under any  Contract.  The Company has not waived any
material  right under any  Contract,  and no consents or  approvals  (other than
those  obtained in writing and delivered to Prime prior to Closing) are required
under  any  Contract  in  connection  with  the  sale of  Capital  Stock  or the
consummation  of the  transactions  contemplated  hereby.  The  Company  has not
guaranteed any obligation of any other person or entity.

         3.13 Claims and Proceedings. Attached hereto as Schedule 3.13 is a list
and description of all claims, actions, suits,  proceedings,  and investigations
pending or, to the knowledge of the Company and Seller,  threatened  against the
Company,  at law or in  equity,  or before or by any court,  municipal  or other
governmental department,  commission, board, agency, or instrumentality.  Except
as set forth on Schedule 3.13  attached  hereto,  none of such claims,  actions,
suits,  proceedings,  or investigations  will result in any liability or loss to
the Company  which  (individually  or in the  aggregate)  is  material,  and the
Company  has not  been,  and the  Company  is not  now,  subject  to any  order,
judgment,  decree,  stipulation,  or consent of any court, governmental body, or
agency.  No inquiry,  action,  or proceeding has been asserted,  instituted,  or
threatened  against the Company or Seller to restrain or prohibit  the  carrying
out of the  transactions  contemplated  by this  Agreement or to  challenge  the
validity of such  transactions or any part thereof or seeking damages on account
thereof.

         3.14 Taxes.  All federal,  foreign,  state,  county,  and local income,
gross receipts, excise, property,  franchise,  license, sales, use, withholding,
and other tax  (collectively,  "Taxes")  returns,  reports,  and declarations of
estimated tax  (collectively,  "Returns") which were required to be filed by the
company on or before the date hereof have been filed within the time  (including
any  applicable  extensions)  and in the manner  provided  by law,  and all such
Returns are true and correct in all material respects and accurately reflect the
Tax  liabilities  of the Company.  The Company has provided Prime with copies of
all returns  filed for and during the years ended 1998,  1997 and (to the extent
an extension was filed for any return for the year ended 1998) 1996.  All Taxes,
assessments,  penalties,  and  interest  which have become due  pursuant to such
Returns have been paid or adequately  accrued in the Financial  Statements.  The
provisions for Taxes  reflected on the balance sheet  contained in the Financial
Statements are adequate to cover all of the Company's  estimated Tax liabilities
for the respective  periods then ended and all prior periods.  As of the Closing
Date,  the  Company  will not owe any Taxes for any period  prior to the Closing
which  are  not  reflected  on  the  Financial  Statements,   except  for  Taxes
attributable  to the  operations  of the Company  between  June 30, 1999 and the
Closing  Date.  The Company has not executed any presently  effective  waiver or
extension of any statute of limitations  against  assessments  and collection of
Taxes.  There  are  no  pending  or  threatened  claims,  assessments,  notices,
proposals  to assess,  deficiencies,  or audits  (collectively,  "Tax  Actions")
against  the Company  with  respect to any Taxes owed or  allegedly  owed by the
Company. There are no tax liens on any of the assets of the Company.  Proper and
accurate  amounts  have been  withheld  and  remitted by the Company from and in
respect of all persons  from whom it is required by  applicable  law to withhold
for all  periods  in  compliance  with  the tax  withholding  provisions  of all
applicable laws and  regulations.  The Company is not a party to any tax sharing
agreement.

         3.15 Personnel. Attached hereto as Schedule 3.15 is a list of names and
current annual rates of compensation of the officers, employees or agents of the
Company who are necessary  for the operation of the Business (the  "Employees").
Except as set forth on  Schedule  3.15,  there  are no  bonus,  profit  sharing,
percentage  compensation,  company automobile,  club membership,  and other like
benefits,  if any, paid or payable by the Company to any Employees from December
31, 1998 through the Closing Date. Schedule 3.15 attached hereto also contains a
brief   description  of  all  material   terms  of  employment   agreements  and
confidentiality  agreements  to which the  Company is a party and all  severance
benefits which any director,  officer,  Employee or sales  representative of the
Company is or may be  entitled to receive.  The Company has  delivered  to Prime
accurate and complete copies of all such employment agreements,  confidentiality
agreements, and all other agreements,  plans, and other instruments to which the
Company  is a party and under  which  its  employees  are  entitled  to  receive
benefits of any nature.  There is no pending or threatened  (i) labor dispute or
union  organization  campaign  relating to the Company,  (ii) claims against the
Company by any  employees  of the  Company  (other than those  certain  Workers'
Compensation  claims   specifically   described  on  Schedule  3.13),  or  (iii)
terminations,  resignations or retirements of any employees of the Company. None
of  the  employees  of  the  Company  are  represented  by any  labor  union  or
organization. There is no unfair labor practice claim against the Company before
the National Labor Relations Board or any strike, labor dispute,  work slowdown,
or work stoppage pending or threatened against or involving the Company.

         3.16 Business  Relations.  The Company has no reason to believe and has
not been  notified  that any  supplier or customer of the Company  will cease or
refuse  to do  business  with the  Company  in the  same  manner  as  previously
conducted  with the  Company  as a result  of or within  one (1) year  after the
consummation  of  the  transactions  contemplated  hereby,  to the  extent  such
cessation or refusal might affect the Business. The Company has not received any
notice  of any  disruption  (including  delayed  deliveries  or  allocations  by
suppliers) in the availability of the materials or products used by the Company.

         3.17 Working  Capital.  Except as set forth on Schedule  3.17  attached
hereto,  all of  the  accounts,  notes,  and  loans  receivable  (the  "Accounts
Receivable")  reflected in the Financial  Statements,  or arising since June 30,
1999, arose from transactions  occurring in the ordinary course of the Company's
business as previously  conducted,  are bona fide and represent  amounts validly
due,  subject to offsets or  defenses.  Except for  accounts  payable  and other
accrued expenses incurred in the ordinary course of the Company's business since
June 30, 1999 and consistent  with past  practices of the Company,  there are no
liabilities  of  the  Company  other  than  those  reflected  in  the  Financial
Statements.   Adequate  provision  has  been  made  for  uncollectible  Accounts
Receivable.  Since  June 30,  1999,  the  Company  has  collected  its  Accounts
Receivable  and has paid or performed all  liabilities  and  obligations  of the
Company in the ordinary  course,  consistent  with past  practices.  The Working
Capital (as hereinafter  defined) of the Company existing on the Closing Date is
equal to or greater than $100,000.

         3.18 Agents.  Except as set forth on Schedule 3.18 attached hereto, the
Company has not  designated  or appointed  any person  (other than the Company's
employees and officers) or other entity to act for it or on its behalf  pursuant
to any power of attorney or any agency which is presently in effect.

         3.19  Indebtedness To and From Directors,  Officers,  Shareholders  and
Employees.  The Company does not owe any  indebtedness  to any of its directors,
officers, shareholders, employees or affiliates, or have indebtedness owed to it
from any of its  directors,  officers,  shareholders,  employees or  affiliates,
excluding  indebtedness  for travel  advances or similar  advances  for expenses
incurred on behalf of and in the ordinary  course of business of the Company and
consistent with the Company's past  practices.  As of the Effective Time and the
Closing  Date all amounts due the Company from any of its  directors,  officers,
employees or affiliates (or any of their family  members) shall have been repaid
in full.

         3.20 Commission Sales  Contracts.  Except as disclosed in Schedule 3.20
attached hereto,  the Company does not employ or have any relationship  with any
individual,  corporation,  partnership,  or other entity whose compensation from
the Company is in whole or in part determined on a commission basis.

         3.21 Certain  Consents.  Except as set forth on Schedule  3.21 attached
hereto,  there are no consents,  waivers,  or approvals  required to be executed
and/or  obtained  by the  Company  from  third  parties in  connection  with the
execution,  delivery,  and  performance  of this  Agreement  or any of the other
contracts, documents, instruments or agreements to be entered into in connection
with  or as  contemplated  by this  Agreement  (all of  which  are  collectively
referred to as the "Transaction Documents").

         3.22 Brokers.  The Company has not engaged,  or caused any liability to
be incurred to, any finder,  broker,  or sales agent (and has not paid, and will
not pay,  any  finders  fee or  similar  fee or  commission  to any  person)  in
connection with the execution, delivery, or performance of this Agreement or the
transactions contemplated hereby.

         3.23 Interest in Competitors,  Suppliers, and Customers.  Except as set
forth on Schedule 3.23 attached hereto, neither the Company nor any affiliate of
the  Company,  and to the  knowledge  of the Company and  Seller,  no  director,
officer,  employee or affiliate of the Company or any affiliate of any director,
officer, employee or affiliate of the Company, has any ownership interest in any
competitor,  customer or supplier  of the  Company or any  property  used in the
operation of the Business.

         3.24 Warranties.  Except as set forth on Schedule 3.24, the Company has
not made any  warranties  or  guarantees  to third  parties  with respect to any
products  sold or services  rendered by it. Except as set forth on Schedule 3.24
attached hereto, no claims for breach of product or service warranties have been
made against the Company since January 1, 1996.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

     (b) execute and deliver each of the Transaction  Documents to which it is a
party; and

                  (c)  deliver   such  good   standing   certificates,   officer
certificates,  and similar  documents and certificates as counsel for Seller may
reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit B;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  C,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  D,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
the Company,  not  specifically and fully reflected by item and amount on either
Schedule 3.4 or in the  Financial  Statements,  that is or may be asserted  with
respect to any acts or omissions  occurring,  or circumstances  existing,  on or
prior to the Closing  Date,  except for  liabilities  incurred  in the  ordinary
course of business,  or (iii) any obligations or liabilities with respect to any
claims  arising out of actions or omissions,  that occurred prior to the Closing
Date,  by  any of  the  Company's  directors,  officers,  shareholders,  agents,
employees, representatives, subsidiaries and/or affiliates.

                  (b) Seller  agrees to indemnify  and hold harmless each of the
Prime  Indemnified  Parties  from and against any and all  Indemnified  Costs in
connection with the  commencement  or assertion of any third-party  action which
any of the Prime Indemnified  Parties may sustain,  arising out of any breach or
default  by  Seller  of any of its  representations,  warranties,  covenants  or
agreements contained in this Agreement or any Transaction Document.

                  (c) Notwithstanding the foregoing,  no Prime Indemnified Party
shall be entitled to assert any claim for indemnification under this Section 6.1
unless and until such time as all claims of all Prime Indemnified Parties, taken
together,  exceed  $10,000  in the  aggregate,  at which time all claims of such
Prime  Indemnified  Parties  may  be  asserted  individually  or in  combination
(beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section 6.1 shall be limited to the aggregate  Purchase Price received by Seller
under this Agreement,  plus the greater of (a) the value of all remaining equity
interests  which  Seller  holds in the Company at the time of Closing or (b) the
value of all remaining equity interests which Seller holds in the Company at the
time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

         Notwithstanding  the foregoing,  no Seller  Indemnified  Party shall be
entitled to assert any claim for  indemnification  under this Section 7.1 unless
and until such time as all claims of such Seller Indemnified Party, individually
and not in combination with other Seller Indemnified Parties,  exceed $25,000 in
the aggregate,  at which time all claims of such Seller Indemnified Party may be
asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding any transfers governed by Section 9.3), (iii)
relocation  of Seller's  primary  residence  outside of a two hundred (200) mile
radius of the center or facility at which Seller primarily renders services,  or
(iv) if Seller is a physician or other  practicing  licensed  professional,  the
performance by Seller, during any one-month period, of greater than thirty (30%)
of his or her  professional  medical  activities  outside of a two hundred (200)
mile radius of the center or facility  primarily utilized by Seller prior to the
date  of  this  Agreement;  the  Seller's  executor,   administrator,   trustee,
custodian,   receiver   or  other   legal  or   personal   representative   (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or relocation of primary residence or practice, as the case may be, within which
time  it may  require  that  the  Company  purchase  (subject  to the  remaining
provisions  of this  subsection)  all of Seller's  capital stock of the Company,
upon the terms and conditions  hereinafter  set forth,  by giving notice of such
election in writing to the  Company.  The Company  may, in its sole  discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

         9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital Contributions.  Without in any way limiting or
qualifying  the  representation  and warranty  with  respect to Working  Capital
contained in Section 3.17, all parties to this Agreement  acknowledge  and agree
that no  shareholder  of the  Company,  or any other party,  has any  obligation
existing on the Closing Date to make a capital contribution to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                  IN ADDITION, SHARES MAY BE TRANSFERRED ONLY IN COMPLIANCE WITH
                  CERTAIN  CONDITIONS  SPECIFIED  IN A  CERTAIN  STOCK  PURCHASE
                  AGREEMENT  DATED EFFECTIVE AS OF SEPTEMBER 1, 1999, A COMPLETE
                  AND CORRECT COPY OF WHICH IS AVAILABLE  FOR  INSPECTION AT THE
                  PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE  FURNISHED TO THE
                  HOLDER HEREOF UPON WRITTEN REQUEST AND WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Invalid Provisions.  If any provision of this Agreement is held to
be  illegal,  invalid,  or  unenforceable  under  present or future  laws,  such
provision shall be fully severable, this Agreement shall be construed as if such
illegal,  invalid, or unenforceable provision had never comprised a part of this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                              1301 Capital of Texas Highway
                                    Suite C-300
                                    Austin, Texas 78746
                                    Attention: President

with a copy to:                     Mr. Timothy L. LaFrey
                                    Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                    816 Congress Avenue, Suite 1900
                                    Austin, Texas 78701

Company:                            Horizon Vision Centers, Inc.
                                    14895 East 14th St., Suite 400
                                    San Leandro, California   94578

Seller:                             David P. and Jane A. Bates
                                    1320 Canyon Side Avenue
                                    San Ramon, California   94583

     Each party may change its  address for  purposes of this  Section by proper
notice to the other parties.

     10.7 Survival of Representations,  Warranties, and Covenants. Regardless of
any investigation at any time made by or on behalf of any party hereto or of any
information any party may have in respect  thereof,  all covenants,  agreements,
representations,  and  warranties  made  hereunder  or  pursuant  hereto  or  in
connection with the transactions contemplated hereby shall survive the Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within the actual  knowledge  of the  officers  of the Company
holding office immediately prior to the Closing, and any employee of the Company
who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Secretary & Manager

Seller:                                     /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            /s/ Jane A. Bates

                                            Printed Name:  Jane A. Bates

Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President

<PAGE>

                                TABLE OF EXHIBITS

EXHIBIT A:        Financial Statements
EXHIBIT B:        Form of Exclusive Use Agreement
EXHIBIT C:        Form of Assignment and Security Agreement
EXHIBIT D:        Form of Amended and Restated Bylaws of Seller

<PAGE>
                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.

                           --------------------------

                                       and

                           Horizon Vision Center, Inc.

                              --------------------

                             Dated September 1, 1999

<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision  Center,  Inc.,  a Nevada  corporation  (the  "Company")  and John Robert
Griffin,  M.D., Family Revocable Trust dated February 8, 1991, and a shareholder
of the Company ("Seller").

The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
23,939  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock certificate  number C- 22
and C-59 (collectively, the "Capital Stock"). The purchase price for the Capital
Stock shall be $271,537.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

            Representations and Warranties of the Company and Seller

         Seller and the Company hereby  represent and warrant to Prime,  jointly
and  severally,  that each of the  following  matters is true and correct in all
respects as of the Closing  Date (with the  understanding  that Prime is relying
materially  on each  such  representation  and  warranty  in  entering  into and
performing this Agreement),  which  representations and warranties shall also be
deemed  made as of the  Effective  Time and which  shall  survive  the  Closing;
provided,  however,  that all  representations  and  warranties  made by  Seller
hereunder shall be deemed made by Seller only to the actual knowledge of Seller.

         3.1 Due  Organization.  The Company is a  corporation  duly  organized,
validly existing, and in good standing under the laws of the State of Nevada and
has full power and  authority to carry on its business as now  conducted  and as
proposed to be conducted. The Company is qualified to do business and is in good
standing  in the states set forth on  Schedule  3.1(a)  attached  hereto,  which
states represent every jurisdiction where such qualification is required for the
conduct of the Company's business as conducted on the Closing Date. Complete and
correct copies of the Company's Articles of Incorporation,  Bylaws, all board of
directors'  resolutions,  all  shareholders'  resolutions,  and  all  amendments
thereto,  have been  delivered to Prime.  Schedule  3.1(b) sets forth a true and
complete  list,  as of the Closing  Date, of all of the holders of any equity or
other ownership interest in the Company or of any right to obtain, by conversion
or otherwise,  and regardless of whether  presently  exercisable,  any equity or
other  ownership  interest in the  Company;  in each case showing the number and
type of interest  or right held.  Schedule  3.1(b) also  identifies  each of the
persons  listed   therein  that  is  a  physician  or  other  licensed   medical
professional,  and describes  each such  person's  license(s)  and  professional
title. Except as set forth on Schedule 3.1(b),  immediately prior to the Closing
Date there are outstanding (i) no shares of equity or other voting securities of
the Company,  (ii) no securities of the Company convertible into or exchangeable
for shares of equity or other voting securities of the Company, (iii) no options
or other rights to acquire from the Company or Seller,  and no obligation of the
Company or Seller to issue or sell, any equity or other voting securities of the
Company or any securities of the Company  convertible  into or exchangeable  for
such equity or voting securities,  and (iv) no equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar  rights of or with respect to the Company.  Immediately  following
the Closing of this transaction and the closings of the Related Acquisitions (as
hereinafter  defined),  Prime will own sixty  percent (60%) of all of the voting
equity  securities of the Company (after  assuming the  conversion,  exchange or
exercise of any and all securities or rights  convertible  into, or exchangeable
or exercisable for, voting equity  securities of the Company),  and all of those
persons and entities listed on Schedule 3.1(b) will own, in the aggregate, forty
percent  (40%) of all of the voting  equity  securities  of the  Company  (after
assuming  the  conversion,  exchange or exercise  of any and all  securities  or
rights  convertible  into, or  exchangeable  or exercisable  for,  voting equity
securities of the Company).  The Capital Stock transferred by Seller to Prime at
the Closing,  as well as all other capital stock of the Company  transferred  to
Prime in the Related Acquisitions,  will be duly authorized,  validly issued and
outstanding,  fully  paid,  non-assessable,  and free of any  liens,  claims  or
encumbrances whatsoever.

         3.2  Subsidiaries.  Except as set  forth on  Schedule  3.2  (reflecting
ownership  interests  and the nature of such  interests),  the Company  does not
directly or indirectly  have (or possess any options or other rights to acquire)
any  subsidiaries or any direct or indirect  ownership  interests in any person,
business,  corporation,  partnership,  limited liability  company,  association,
joint venture, trust, or other entity.

         3.3 Due  Authorization.  Each of the  Company and Seller has full power
and  authority to enter into and perform  this  Agreement  and each  Transaction
Document  required  to be  executed  by the  Company  or  Seller  in  connection
herewith.  The execution,  delivery,  and performance of this Agreement and each
such  Transaction  Document has been duly authorized by all necessary  action of
the Company,  its directors,  its officers and its shareholders.  This Agreement
and each such  Transaction  Document  has been  duly and  validly  executed  and
delivered  by the  Company  and  Seller  and  constitutes  a valid  and  binding
obligation  of the  Company  and  Seller,  enforceable  against  each of them in
accordance  with its terms.  The execution,  delivery,  and  performance of this
Agreement,  and each  Transaction  Document  required  herein to be  executed by
Seller  and/or the Company do not (a) violate any  federal,  state,  county,  or
local law,  rule,  or  regulation  applicable  to the Company,  the Business (as
hereinafter defined),  the Company's assets or the Capital Stock, (b) violate or
conflict with, or permit the cancellation of, any agreement to which the Company
is a party,  or by which the Company or its properties  are bound,  or result in
the creation of any lien, security interest,  charge, or encumbrance upon any of
such  properties or the upon the Capital Stock,  (c) permit the  acceleration of
the maturity of any  indebtedness of Seller or the Company,  or any indebtedness
secured by the Capital  Stock or by the property of the Company,  or (d) violate
or conflict with any provision of the  organizational  documents of the Company.
No action,  consent,  waiver or approval of, or filing with, any federal, state,
county or local  governmental  authority is required by Seller or the Company in
connection  with the execution,  delivery,  or performance of this Agreement (or
any Transaction Document).

         3.4  Financial  Statements.  The  unaudited  balance  sheet and  income
statement  of the  Company as of and for each of the years  ended March 31, 1998
and 1999, and the unaudited balance sheet and income statement of the Company as
of and for  the  three  (3)  months  ended  June  30,  1999  (collectively,  the
"Financial  Statements")  are  attached  hereto  as  Exhibit  A.  The  Financial
Statements have been prepared in accordance with generally  accepted  accounting
principles  consistently  applied ("GAAP") (except as specifically noted therein
or in Schedule  3.4) and fairly  present the  financial  position and results of
operations  of the  Company  as of the  indicated  dates  and for the  indicated
periods.  Except for liabilities  incurred in the ordinary course of business or
disclosed  in  Schedule  3.4,  and except to the extent  specifically  and fully
reflected in the Financial Statements  (including the notes thereto),  as of the
Closing Date, the Company has no claims,  debts,  liabilities,  or  obligations,
whether known or unknown, absolute,  contingent or otherwise (including, but not
limited to,  federal,  state,  and local taxes,  any sales taxes,  use taxes and
property  taxes,  any taxes arising from the  transactions  contemplated by this
Agreement and any liabilities arising from any litigation or civil,  criminal or
regulatory  proceeding  involving or related to the  Company,  its assets or the
Business).  The  Company and Seller each agree to  indemnify  and hold  harmless
Prime  and its  affiliates  from and  against  any and all such  claims,  debts,
liabilities and obligations.  Except as set forth in Schedule 3.4 hereto,  since
June 30,  1999 there has been no  material  adverse  change in the assets of the
Company, the Business, or the results of operations or financial position of the
Company.

         3.5 Conduct of Business;  Certain Actions.  As used herein,  "Business"
means all of the business  conducted  by the  Company,  which shall be deemed to
include  all  refractive  surgery  modalities,  now  performed,  offered or made
available, including, without limitation,  implantable contact lenses, instromal
corneal  rings,  laser  in  situs  keratomileusis  photorefractive  keratectomy,
automated lemellar  keratoplasty,  radial keratotomy,  astigmatic keratotomy and
similar procedures.  Except as set forth on Schedule 3.5 attached hereto,  since
June 30, 1999,  the Company has  conducted  its Business and  operations  of the
Business in the ordinary  course and consistent  with its past practices and has
not (a)  purchased  or retired  any  indebtedness,  or  purchased,  retired,  or
redeemed any  ownership  interest  from,  any  director,  officer,  shareholder,
employee or affiliate of the Company,  or engaged in any other  transaction that
involves or requires  distributions of money or other assets from the Company to
any director, officer, shareholder, employee or affiliate of the Company if such
other  transaction  is not done in the  ordinary  course of business  and is not
consistent with past practices of the Company, (b) increased the compensation of
any  directors,  officers,  employees,  agents,  contractors,  vendors  or other
parties,  except for wage and salary  increases  made in the ordinary  course of
business and consistent with the past practices of the Company, (c) made capital
expenditures  exceeding  $10,000  individually or $25,000 in the aggregate,  (d)
sold any asset (or any group of related assets) in any transaction (or series of
related  transactions)  in which the purchase price or book value for such asset
(or group of related assets) exceeded  $10,000,  (e) discharged or satisfied any
lien or encumbrance or paid any obligation or liability, absolute or contingent,
other than  current  liabilities  incurred  and paid in the  ordinary  course of
business,  (f) made or guaranteed any loans or advances to any party whatsoever,
(g) suffered or permitted any lien, security interest,  claim,  charge, or other
encumbrance to arise or be granted or created against or upon any of its assets,
real or personal,  tangible or intangible, (h) canceled, waived, or released any
of its  debts,  rights,  or  claims  against  third  parties,  (i)  amended  its
organizational  documents, (j) made or paid any severance or termination payment
to any director, officer, employee, agent, contractor, vendor or consultant, (k)
made any  change  in its  method  of  accounting,  (l) made  any  investment  or
commitment  therefor  in  any  person,   business,   corporation,   association,
partnership,  limited liability company, joint venture,  trust, or other entity,
(m) made, entered into, amended, or terminated any written employment  contract,
created,  made,  amended,  or  terminated  any  bonus,  stock  option,  pension,
retirement,  profit sharing,  or other employee benefit plan or arrangement,  or
withdrawn  from any  "multi-employer  plan" (as defined in the Internal  Revenue
Code of 1986, as amended (the "Code")) so as to create any liability under ERISA
(as  hereinafter  defined) to any person or entity,  (n) amended,  terminated or
experienced a termination of any material contract, agreement, lease, franchise,
or license  to which it is a party,  (o) made any  distributions,  in cash or in
kind, to its  shareholders,  or to any person or entity related to or affiliated
therewith,  in any  capacity,  except  such  distributions  as are  made  in the
ordinary course of the Company's  business  consistent with past practices,  (p)
entered into any other material  transactions  except in the ordinary  course of
business, (q) entered into any contract, commitment, agreement, or understanding
to do any acts described in the foregoing  clauses (a)-(p) of this Section,  (r)
suffered any material  damage,  destruction,  or loss (whether or not covered by
insurance) to any assets,  (s) experienced any strike,  slowdown,  or demand for
recognition by a labor  organization by or with respect to any of its employees,
or (t)  experienced  or effected any  shutdown,  slow-down,  or cessation of any
operations conducted by, or constituting part of, it.

         3.6 Assets;  Licenses,  Permits,  etc.  Except as set forth on Schedule
3.6(a), the Company has good and marketable title to all of its assets, free and
clear  of  all  liens,  security  interests,  claims,  rights  of  another,  and
encumbrances  of any kind  whatsoever.  The  assets of the  Company  are in good
operating  condition and repair,  subject to ordinary wear and tear, taking into
account the  respective  ages of the  properties  involved  and are all that are
necessary for the conduct of the Business. Attached hereto as Schedule 3.6(b) is
a list and description of all federal,  state,  county,  and local  governmental
licenses,  certificates,  certificates of need,  permits,  waivers,  filings and
orders  held or applied  for by the Company and used or relied on (or to be used
or relied on) in  connection  with the  Business  ("Permits").  The  Company has
complied  in all  material  respects,  and the Company is in  compliance  in all
material  respects,  with the  terms  and  conditions  of any such  Permits.  No
additional  Permit  is  required  from  any  federal,  state,  county,  or local
governmental  agency or body  thereof  in  connection  with the  conduct  of the
Business.  No claim has been made by any  governmental  authority  (and,  to the
knowledge of Seller and the Company,  no such claim has been  threatened) to the
effect that a Permit not possessed by the Company is necessary in respect of the
Business.

         3.7      Environmental Issues.

                  (a) For purposes of this  Agreement,  the term  "environmental
laws"  shall  mean  all  laws  and  regulations  relating  to  the  manufacture,
processing,  distribution,  use, treatment,  storage,  disposal,  transport,  or
handling, or the emission, discharge, or release, of any pollutant, contaminant,
chemical,  or industrial  toxic or hazardous  substance or waste,  and any order
related thereto.

                  (b) The Company has complied in all material respects with and
obtained  all  authorizations  and made all filings  required by all  applicable
environmental laws. The properties occupied or used by the Company have not been
contaminated with any hazardous wastes, hazardous substances, or other hazardous
or toxic  materials  in  violation  of any  applicable  environmental  law,  the
violation of which could have a material  adverse  impact on the Business or the
financial position of the Company.

                  (c) The  Company has not  received  any notice from the United
States  Environmental  Protection  Agency that it is a  potentially  responsible
party under the Comprehensive Environmental Response, Compensation and Liability
Act  ("Superfund  Notice"),  any  citation  from  any  federal,  state  or local
governmental  authority for non-compliance with its requirements with respect to
air, water or environmental pollution, or the improper storage, use or discharge
of any  hazardous  waste,  other  waste or  other  substance  or other  material
pertaining to its business  ("Citations") or any written notice from any private
party alleging any such  non-compliance;  and there are no pending or unresolved
Superfund  Notices,  Citations or written notices from private parties  alleging
any such non-compliance.

         3.8  Intellectual  Property Rights.  There are no patents,  trademarks,
trade names, or copyrights, and no applications therefor, owned by or registered
in the name of the Company or in which the Company  has any right,  license,  or
interest.  The  Company  is not a party  to any  license  agreement,  either  as
licensor or licensee, with respect to any patents,  trademarks,  trade names, or
copyrights.  The Company has not received any notice that it is  infringing  any
patent, trademark, trade name, or copyright of others.

         3.9  Compliance  with Laws. To the knowledge of the Company and Seller,
the  Company  has  complied  in all  material  respects,  and the  Company is in
compliance in all material respects,  with all federal, state, county, and local
laws, rules,  regulations and ordinances  currently in effect. No claim has been
made or  threatened  by any  governmental  authority  against the Company to the
effect that the business conducted by the Company fails to comply in any respect
with any law, rule, regulation, or ordinance.

         3.10  Insurance.  Attached  hereto  as  Schedule  3.10 is a list of all
policies of fire, liability, business interruption, and other forms of insurance
(including,  without  limitation,  professional  liability  insurance)  and  all
fidelity  bonds held by or applicable to the Company at any time within the past
three (3) years,  which  schedule  sets forth in respect of each such policy the
policy name, policy number,  carrier, term, type of coverage,  deductible amount
or self-insured retention amount, limits of coverage, and annual premium. To the
knowledge of the Company and Seller,  no event directly  relating to the Company
has occurred  which will result in a retroactive  upward  adjustment of premiums
under any such policies or which is likely to result in any  prospective  upward
adjustment in such premiums.  There have been no material changes in the type of
insurance  coverage  maintained by the Company  during the past three (3) years,
including without  limitation any change which has resulted in any period during
which the Company had no insurance coverage.  Excluding insurance policies which
have  expired and been  replaced,  no  insurance  policy of the Company has been
canceled  within  the last three (3) years and no threat has been made to cancel
any insurance policy of the Company within such period.

         3.11 Employee  Benefit  Matters.  Except as set forth on Schedule 3.11,
the  Company  does not  maintain  nor does it  contribute  nor is it required to
contribute to any "employee welfare benefit plan" (as defined in section 3(1) of
the  Employee  Retirement  Income  Security Act of 1974 (and any sections of the
Code amended by it) and all regulations promulgated thereunder, as the same have
from time to time been amended ("ERISA")) or any "employee pension benefit plan"
(as defined in ERISA).  The Company  does not  presently  maintain and has never
maintained,  or had any  obligation of any nature to  contribute  to, a "defined
benefit plan" within the meaning of the Code.

         3.12 Contracts and  Agreements.  Attached  hereto as Schedule 3.12 is a
list of all written or oral contracts, commitments, leases, and other agreements
(including, without limitation, all promissory notes, loan agreements, and other
evidences  of  indebtedness,  mortgages,  deeds of trust,  security  agreements,
pledge agreements,  service  agreements,  and similar agreements and instruments
and all confidentiality  agreements) to which the Company is a party or by which
the  Company or its  properties  are bound,  pursuant  to which the  obligations
thereunder of any party thereto are, or are contemplated as being, in respect of
any such individual contracts,  commitments,  leases, or other agreements during
any year during the term  thereof,  $25,000 or greater,  or which are  otherwise
material to the Business  (collectively  the  "Contracts"  and  individually,  a
"Contract").  The Company is not and, to the best  knowledge  of the Company and
Seller,  no other party thereto is in default (and no event has occurred  which,
with the passage of time or the giving of notice,  or both,  would  constitute a
default by the Company or, to the best  knowledge of the Company and Seller,  by
any other  party  thereto)  under any  Contract.  The Company has not waived any
material  right under any  Contract,  and no consents or  approvals  (other than
those  obtained in writing and delivered to Prime prior to Closing) are required
under  any  Contract  in  connection  with  the  sale of  Capital  Stock  or the
consummation  of the  transactions  contemplated  hereby.  The  Company  has not
guaranteed any obligation of any other person or entity.

         3.13 Claims and Proceedings. Attached hereto as Schedule 3.13 is a list
and description of all claims, actions, suits,  proceedings,  and investigations
pending or, to the knowledge of the Company and Seller,  threatened  against the
Company,  at law or in  equity,  or before or by any court,  municipal  or other
governmental department,  commission, board, agency, or instrumentality.  Except
as set forth on Schedule 3.13  attached  hereto,  none of such claims,  actions,
suits,  proceedings,  or investigations  will result in any liability or loss to
the Company  which  (individually  or in the  aggregate)  is  material,  and the
Company  has not  been,  and the  Company  is not  now,  subject  to any  order,
judgment,  decree,  stipulation,  or consent of any court, governmental body, or
agency.  No inquiry,  action,  or proceeding has been asserted,  instituted,  or
threatened  against the Company or Seller to restrain or prohibit  the  carrying
out of the  transactions  contemplated  by this  Agreement or to  challenge  the
validity of such  transactions or any part thereof or seeking damages on account
thereof.

         3.14 Taxes.  All federal,  foreign,  state,  county,  and local income,
gross receipts, excise, property,  franchise,  license, sales, use, withholding,
and other tax  (collectively,  "Taxes")  returns,  reports,  and declarations of
estimated tax  (collectively,  "Returns") which were required to be filed by the
company on or before the date hereof have been filed within the time  (including
any  applicable  extensions)  and in the manner  provided  by law,  and all such
Returns are true and correct in all material respects and accurately reflect the
Tax  liabilities  of the Company.  The Company has provided Prime with copies of
all returns  filed for and during the years ended 1998,  1997 and (to the extent
an extension was filed for any return for the year ended 1998) 1996.  All Taxes,
assessments,  penalties,  and  interest  which have become due  pursuant to such
Returns have been paid or adequately  accrued in the Financial  Statements.  The
provisions for Taxes  reflected on the balance sheet  contained in the Financial
Statements are adequate to cover all of the Company's  estimated Tax liabilities
for the respective  periods then ended and all prior periods.  As of the Closing
Date,  the  Company  will not owe any Taxes for any period  prior to the Closing
which  are  not  reflected  on  the  Financial  Statements,   except  for  Taxes
attributable  to the  operations  of the Company  between  June 30, 1999 and the
Closing  Date.  The Company has not executed any presently  effective  waiver or
extension of any statute of limitations  against  assessments  and collection of
Taxes.  There  are  no  pending  or  threatened  claims,  assessments,  notices,
proposals  to assess,  deficiencies,  or audits  (collectively,  "Tax  Actions")
against  the Company  with  respect to any Taxes owed or  allegedly  owed by the
Company. There are no tax liens on any of the assets of the Company.  Proper and
accurate  amounts  have been  withheld  and  remitted by the Company from and in
respect of all persons  from whom it is required by  applicable  law to withhold
for all  periods  in  compliance  with  the tax  withholding  provisions  of all
applicable laws and  regulations.  The Company is not a party to any tax sharing
agreement.

         3.15 Personnel. Attached hereto as Schedule 3.15 is a list of names and
current annual rates of compensation of the officers, employees or agents of the
Company who are necessary  for the operation of the Business (the  "Employees").
Except as set forth on  Schedule  3.15,  there  are no  bonus,  profit  sharing,
percentage  compensation,  company automobile,  club membership,  and other like
benefits,  if any, paid or payable by the Company to any Employees from December
31, 1998 through the Closing Date. Schedule 3.15 attached hereto also contains a
brief   description  of  all  material   terms  of  employment   agreements  and
confidentiality  agreements  to which the  Company is a party and all  severance
benefits which any director,  officer,  Employee or sales  representative of the
Company is or may be  entitled to receive.  The Company has  delivered  to Prime
accurate and complete copies of all such employment agreements,  confidentiality
agreements, and all other agreements,  plans, and other instruments to which the
Company  is a party and under  which  its  employees  are  entitled  to  receive
benefits of any nature.  There is no pending or threatened  (i) labor dispute or
union  organization  campaign  relating to the Company,  (ii) claims against the
Company by any  employees  of the  Company  (other than those  certain  Workers'
Compensation  claims   specifically   described  on  Schedule  3.13),  or  (iii)
terminations,  resignations or retirements of any employees of the Company. None
of  the  employees  of  the  Company  are  represented  by any  labor  union  or
organization. There is no unfair labor practice claim against the Company before
the National Labor Relations Board or any strike, labor dispute,  work slowdown,
or work stoppage pending or threatened against or involving the Company.

         3.16 Business  Relations.  The Company has no reason to believe and has
not been  notified  that any  supplier or customer of the Company  will cease or
refuse  to do  business  with the  Company  in the  same  manner  as  previously
conducted  with the  Company  as a result  of or within  one (1) year  after the
consummation  of  the  transactions  contemplated  hereby,  to the  extent  such
cessation or refusal might affect the Business. The Company has not received any
notice  of any  disruption  (including  delayed  deliveries  or  allocations  by
suppliers) in the availability of the materials or products used by the Company.

         3.17 Working  Capital.  Except as set forth on Schedule  3.17  attached
hereto,  all of  the  accounts,  notes,  and  loans  receivable  (the  "Accounts
Receivable")  reflected in the Financial  Statements,  or arising since June 30,
1999, arose from transactions  occurring in the ordinary course of the Company's
business as previously  conducted,  are bona fide and represent  amounts validly
due,  subject to offsets or  defenses.  Except for  accounts  payable  and other
accrued expenses incurred in the ordinary course of the Company's business since
June 30, 1999 and consistent  with past  practices of the Company,  there are no
liabilities  of  the  Company  other  than  those  reflected  in  the  Financial
Statements.   Adequate  provision  has  been  made  for  uncollectible  Accounts
Receivable.  Since  June 30,  1999,  the  Company  has  collected  its  Accounts
Receivable  and has paid or performed all  liabilities  and  obligations  of the
Company in the ordinary  course,  consistent  with past  practices.  The Working
Capital (as hereinafter  defined) of the Company existing on the Closing Date is
equal to or greater than $100,000.

         3.18 Agents.  Except as set forth on Schedule 3.18 attached hereto, the
Company has not  designated  or appointed  any person  (other than the Company's
employees and officers) or other entity to act for it or on its behalf  pursuant
to any power of attorney or any agency which is presently in effect.

         3.19  Indebtedness To and From Directors,  Officers,  Shareholders  and
Employees.  The Company does not owe any  indebtedness  to any of its directors,
officers, shareholders, employees or affiliates, or have indebtedness owed to it
from any of its  directors,  officers,  shareholders,  employees or  affiliates,
excluding  indebtedness  for travel  advances or similar  advances  for expenses
incurred on behalf of and in the ordinary  course of business of the Company and
consistent with the Company's past  practices.  As of the Effective Time and the
Closing  Date all amounts due the Company from any of its  directors,  officers,
employees or affiliates (or any of their family  members) shall have been repaid
in full.

         3.20 Commission Sales  Contracts.  Except as disclosed in Schedule 3.20
attached hereto,  the Company does not employ or have any relationship  with any
individual,  corporation,  partnership,  or other entity whose compensation from
the Company is in whole or in part determined on a commission basis.

         3.21 Certain  Consents.  Except as set forth on Schedule  3.21 attached
hereto,  there are no consents,  waivers,  or approvals  required to be executed
and/or  obtained  by the  Company  from  third  parties in  connection  with the
execution,  delivery,  and  performance  of this  Agreement  or any of the other
contracts, documents, instruments or agreements to be entered into in connection
with  or as  contemplated  by this  Agreement  (all of  which  are  collectively
referred to as the "Transaction Documents").

         3.22 Brokers.  The Company has not engaged,  or caused any liability to
be incurred to, any finder,  broker,  or sales agent (and has not paid, and will
not pay,  any  finders  fee or  similar  fee or  commission  to any  person)  in
connection with the execution, delivery, or performance of this Agreement or the
transactions contemplated hereby.

         3.23 Interest in Competitors,  Suppliers, and Customers.  Except as set
forth on Schedule 3.23 attached hereto, neither the Company nor any affiliate of
the  Company,  and to the  knowledge  of the Company and  Seller,  no  director,
officer,  employee or affiliate of the Company or any affiliate of any director,
officer, employee or affiliate of the Company, has any ownership interest in any
competitor,  customer or supplier  of the  Company or any  property  used in the
operation of the Business.

         3.24 Warranties.  Except as set forth on Schedule 3.24, the Company has
not made any  warranties  or  guarantees  to third  parties  with respect to any
products  sold or services  rendered by it. Except as set forth on Schedule 3.24
attached hereto, no claims for breach of product or service warranties have been
made against the Company since January 1, 1996.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

     (b) execute and deliver each of the Transaction  Documents to which it is a
party; and

                  (c)  deliver   such  good   standing   certificates,   officer
certificates,  and similar  documents and certificates as counsel for Seller may
reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit B;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  C,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  D,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
the Company,  not  specifically and fully reflected by item and amount on either
Schedule 3.4 or in the  Financial  Statements,  that is or may be asserted  with
respect to any acts or omissions  occurring,  or circumstances  existing,  on or
prior to the Closing  Date,  except for  liabilities  incurred  in the  ordinary
course of business,  or (iii) any obligations or liabilities with respect to any
claims  arising out of actions or omissions,  that occurred prior to the Closing
Date,  by  any of  the  Company's  directors,  officers,  shareholders,  agents,
employees, representatives, subsidiaries and/or affiliates.

                  (b) Seller  agrees to indemnify  and hold harmless each of the
Prime  Indemnified  Parties  from and against any and all  Indemnified  Costs in
connection with the  commencement  or assertion of any third-party  action which
any of the Prime Indemnified  Parties may sustain,  arising out of any breach or
default  by  Seller  of any of its  representations,  warranties,  covenants  or
agreements contained in this Agreement or any Transaction Document.

                  (c) Notwithstanding the foregoing,  no Prime Indemnified Party
shall be entitled to assert any claim for indemnification under this Section 6.1
unless and until such time as all claims of all Prime Indemnified Parties, taken
together,  exceed  $10,000  in the  aggregate,  at which time all claims of such
Prime  Indemnified  Parties  may  be  asserted  individually  or in  combination
(beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section 6.1 shall be limited to the aggregate  Purchase Price received by Seller
under this Agreement,  plus the greater of (a) the value of all remaining equity
interests  which  Seller  holds in the Company at the time of Closing or (b) the
value of all remaining equity interests which Seller holds in the Company at the
time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

         Notwithstanding  the foregoing,  no Seller  Indemnified  Party shall be
entitled to assert any claim for  indemnification  under this Section 7.1 unless
and until such time as all claims of such Seller Indemnified Party, individually
and not in combination with other Seller Indemnified Parties,  exceed $25,000 in
the aggregate,  at which time all claims of such Seller Indemnified Party may be
asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding any transfers governed by Section 9.3), (iii)
relocation  of Seller's  primary  residence  outside of a two hundred (200) mile
radius of the center or facility at which Seller primarily renders services,  or
(iv) if Seller is a physician or other  practicing  licensed  professional,  the
performance by Seller, during any one-month period, of greater than thirty (30%)
of his or her  professional  medical  activities  outside of a two hundred (200)
mile radius of the center or facility  primarily utilized by Seller prior to the
date  of  this  Agreement;  the  Seller's  executor,   administrator,   trustee,
custodian,   receiver   or  other   legal  or   personal   representative   (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or relocation of primary residence or practice, as the case may be, within which
time  it may  require  that  the  Company  purchase  (subject  to the  remaining
provisions  of this  subsection)  all of Seller's  capital stock of the Company,
upon the terms and conditions  hereinafter  set forth,  by giving notice of such
election in writing to the  Company.  The Company  may, in its sole  discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

         9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital Contributions.  Without in any way limiting or
qualifying  the  representation  and warranty  with  respect to Working  Capital
contained in Section 3.17, all parties to this Agreement  acknowledge  and agree
that no  shareholder  of the  Company,  or any other party,  has any  obligation
existing on the Closing Date to make a capital contribution to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                  IN ADDITION, SHARES MAY BE TRANSFERRED ONLY IN COMPLIANCE WITH
                  CERTAIN  CONDITIONS  SPECIFIED  IN A  CERTAIN  STOCK  PURCHASE
                  AGREEMENT  DATED EFFECTIVE AS OF SEPTEMBER 1, 1999, A COMPLETE
                  AND CORRECT COPY OF WHICH IS AVAILABLE  FOR  INSPECTION AT THE
                  PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE  FURNISHED TO THE
                  HOLDER HEREOF UPON WRITTEN REQUEST AND WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Invalid Provisions.  If any provision of this Agreement is held to
be  illegal,  invalid,  or  unenforceable  under  present or future  laws,  such
provision shall be fully severable, this Agreement shall be construed as if such
illegal,  invalid, or unenforceable provision had never comprised a part of this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                              1301 Capital of Texas Highway
                                    Suite C-300
                                    Austin, Texas 78746
                                    Attention: President

with a copy to:                     Mr. Timothy L. LaFrey
                                    Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                    816 Congress Avenue, Suite 1900
                                    Austin, Texas 78701

Company:                            Horizon Vision Centers, Inc.
                                    14895 East 14th Street, Suite 400
                                    San Leandro, California   94578

Seller:                             John Robert Griffin, M.D., Trustee
                                    Family Revocable Trust
                                    dated February 8, 1991
                                    4913 Puma Way
                                    Carmichael, California   95608

     Each party may change its  address for  purposes of this  Section by proper
notice to the other parties.

     10.7 Survival of Representations,  Warranties, and Covenants. Regardless of
any investigation at any time made by or on behalf of any party hereto or of any
information any party may have in respect  thereof,  all covenants,  agreements,
representations,  and  warranties  made  hereunder  or  pursuant  hereto  or  in
connection with the transactions contemplated hereby shall survive the Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within the actual  knowledge  of the  officers  of the Company
holding office immediately prior to the Closing, and any employee of the Company
who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President

Seller:                                  /s/ John Robert Griffin, M.D., Trustee

                          Printed Name: John Robert Griffin, M.D., Trustee under
                                        the John Robert Griffin, M.D. Family
                                        Revocable Trust dated February 1, 1991

Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President

<PAGE>

                                TABLE OF EXHIBITS

EXHIBIT A:        Financial Statements
EXHIBIT B:        Form of Exclusive Use Agreement
EXHIBIT C:        Form of Assignment and Security Agreement
EXHIBIT D:        Form of Amended and Restated Bylaws of Seller

<PAGE>
                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.

                           --------------------------

                                       and

                           Horizon Vision Center, Inc.

                              --------------------

                             Dated September 1, 1999

<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the "Company") and Mark R. Mandel,
M.D.,  Trustee under Trust  Agreement dated April 12, 1989, and a shareholder of
the Company ("Seller").

The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
79,914  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock certificate  number C-24,
C-36,  C-41, C-44 and C-95  (collectively,  the "Capital  Stock").  The purchase
price for the Capital Stock shall be $906,453.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

            Representations and Warranties of the Company and Seller

         Seller and the Company hereby  represent and warrant to Prime,  jointly
and  severally,  that each of the  following  matters is true and correct in all
respects as of the Closing  Date (with the  understanding  that Prime is relying
materially  on each  such  representation  and  warranty  in  entering  into and
performing this Agreement),  which  representations and warranties shall also be
deemed  made as of the  Effective  Time and which  shall  survive  the  Closing;
provided,  however,  that all  representations  and  warranties  made by  Seller
hereunder shall be deemed made by Seller only to the actual knowledge of Seller.

         3.1 Due  Organization.  The Company is a  corporation  duly  organized,
validly existing, and in good standing under the laws of the State of Nevada and
has full power and  authority to carry on its business as now  conducted  and as
proposed to be conducted. The Company is qualified to do business and is in good
standing  in the states set forth on  Schedule  3.1(a)  attached  hereto,  which
states represent every jurisdiction where such qualification is required for the
conduct of the Company's business as conducted on the Closing Date. Complete and
correct copies of the Company's Articles of Incorporation,  Bylaws, all board of
directors'  resolutions,  all  shareholders'  resolutions,  and  all  amendments
thereto,  have been  delivered to Prime.  Schedule  3.1(b) sets forth a true and
complete  list,  as of the Closing  Date, of all of the holders of any equity or
other ownership interest in the Company or of any right to obtain, by conversion
or otherwise,  and regardless of whether  presently  exercisable,  any equity or
other  ownership  interest in the  Company;  in each case showing the number and
type of interest  or right held.  Schedule  3.1(b) also  identifies  each of the
persons  listed   therein  that  is  a  physician  or  other  licensed   medical
professional,  and describes  each such  person's  license(s)  and  professional
title. Except as set forth on Schedule 3.1(b),  immediately prior to the Closing
Date there are outstanding (i) no shares of equity or other voting securities of
the Company,  (ii) no securities of the Company convertible into or exchangeable
for shares of equity or other voting securities of the Company, (iii) no options
or other rights to acquire from the Company or Seller,  and no obligation of the
Company or Seller to issue or sell, any equity or other voting securities of the
Company or any securities of the Company  convertible  into or exchangeable  for
such equity or voting securities,  and (iv) no equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar  rights of or with respect to the Company.  Immediately  following
the Closing of this transaction and the closings of the Related Acquisitions (as
hereinafter  defined),  Prime will own sixty  percent (60%) of all of the voting
equity  securities of the Company (after  assuming the  conversion,  exchange or
exercise of any and all securities or rights  convertible  into, or exchangeable
or exercisable for, voting equity  securities of the Company),  and all of those
persons and entities listed on Schedule 3.1(b) will own, in the aggregate, forty
percent  (40%) of all of the voting  equity  securities  of the  Company  (after
assuming  the  conversion,  exchange or exercise  of any and all  securities  or
rights  convertible  into, or  exchangeable  or exercisable  for,  voting equity
securities of the Company).  The Capital Stock transferred by Seller to Prime at
the Closing,  as well as all other capital stock of the Company  transferred  to
Prime in the Related Acquisitions,  will be duly authorized,  validly issued and
outstanding,  fully  paid,  non-assessable,  and free of any  liens,  claims  or
encumbrances whatsoever.

         3.2  Subsidiaries.  Except as set  forth on  Schedule  3.2  (reflecting
ownership  interests  and the nature of such  interests),  the Company  does not
directly or indirectly  have (or possess any options or other rights to acquire)
any  subsidiaries or any direct or indirect  ownership  interests in any person,
business,  corporation,  partnership,  limited liability  company,  association,
joint venture, trust, or other entity.

         3.3 Due  Authorization.  Each of the  Company and Seller has full power
and  authority to enter into and perform  this  Agreement  and each  Transaction
Document  required  to be  executed  by the  Company  or  Seller  in  connection
herewith.  The execution,  delivery,  and performance of this Agreement and each
such  Transaction  Document has been duly authorized by all necessary  action of
the Company,  its directors,  its officers and its shareholders.  This Agreement
and each such  Transaction  Document  has been  duly and  validly  executed  and
delivered  by the  Company  and  Seller  and  constitutes  a valid  and  binding
obligation  of the  Company  and  Seller,  enforceable  against  each of them in
accordance  with its terms.  The execution,  delivery,  and  performance of this
Agreement,  and each  Transaction  Document  required  herein to be  executed by
Seller  and/or the Company do not (a) violate any  federal,  state,  county,  or
local law,  rule,  or  regulation  applicable  to the Company,  the Business (as
hereinafter defined),  the Company's assets or the Capital Stock, (b) violate or
conflict with, or permit the cancellation of, any agreement to which the Company
is a party,  or by which the Company or its properties  are bound,  or result in
the creation of any lien, security interest,  charge, or encumbrance upon any of
such  properties or the upon the Capital Stock,  (c) permit the  acceleration of
the maturity of any  indebtedness of Seller or the Company,  or any indebtedness
secured by the Capital  Stock or by the property of the Company,  or (d) violate
or conflict with any provision of the  organizational  documents of the Company.
No action,  consent,  waiver or approval of, or filing with, any federal, state,
county or local  governmental  authority is required by Seller or the Company in
connection  with the execution,  delivery,  or performance of this Agreement (or
any Transaction Document).

         3.4  Financial  Statements.  The  unaudited  balance  sheet and  income
statement  of the  Company as of and for each of the years  ended March 31, 1998
and 1999, and the unaudited balance sheet and income statement of the Company as
of and for  the  three  (3)  months  ended  June  30,  1999  (collectively,  the
"Financial  Statements")  are  attached  hereto  as  Exhibit  A.  The  Financial
Statements have been prepared in accordance with generally  accepted  accounting
principles  consistently  applied ("GAAP") (except as specifically noted therein
or in Schedule  3.4) and fairly  present the  financial  position and results of
operations  of the  Company  as of the  indicated  dates  and for the  indicated
periods.  Except for liabilities  incurred in the ordinary course of business or
disclosed  in  Schedule  3.4,  and except to the extent  specifically  and fully
reflected in the Financial Statements  (including the notes thereto),  as of the
Closing Date, the Company has no claims,  debts,  liabilities,  or  obligations,
whether known or unknown, absolute,  contingent or otherwise (including, but not
limited to,  federal,  state,  and local taxes,  any sales taxes,  use taxes and
property  taxes,  any taxes arising from the  transactions  contemplated by this
Agreement and any liabilities arising from any litigation or civil,  criminal or
regulatory  proceeding  involving or related to the  Company,  its assets or the
Business).  The  Company and Seller each agree to  indemnify  and hold  harmless
Prime  and its  affiliates  from and  against  any and all such  claims,  debts,
liabilities and obligations.  Except as set forth in Schedule 3.4 hereto,  since
June 30,  1999 there has been no  material  adverse  change in the assets of the
Company, the Business, or the results of operations or financial position of the
Company.

         3.5 Conduct of Business;  Certain Actions.  As used herein,  "Business"
means all of the business  conducted  by the  Company,  which shall be deemed to
include  all  refractive  surgery  modalities,  now  performed,  offered or made
available, including, without limitation,  implantable contact lenses, instromal
corneal  rings,  laser  in  situs  keratomileusis  photorefractive  keratectomy,
automated lemellar  keratoplasty,  radial keratotomy,  astigmatic keratotomy and
similar procedures.  Except as set forth on Schedule 3.5 attached hereto,  since
June 30, 1999,  the Company has  conducted  its Business and  operations  of the
Business in the ordinary  course and consistent  with its past practices and has
not (a)  purchased  or retired  any  indebtedness,  or  purchased,  retired,  or
redeemed any  ownership  interest  from,  any  director,  officer,  shareholder,
employee or affiliate of the Company,  or engaged in any other  transaction that
involves or requires  distributions of money or other assets from the Company to
any director, officer, shareholder, employee or affiliate of the Company if such
other  transaction  is not done in the  ordinary  course of business  and is not
consistent with past practices of the Company, (b) increased the compensation of
any  directors,  officers,  employees,  agents,  contractors,  vendors  or other
parties,  except for wage and salary  increases  made in the ordinary  course of
business and consistent with the past practices of the Company, (c) made capital
expenditures  exceeding  $10,000  individually or $25,000 in the aggregate,  (d)
sold any asset (or any group of related assets) in any transaction (or series of
related  transactions)  in which the purchase price or book value for such asset
(or group of related assets) exceeded  $10,000,  (e) discharged or satisfied any
lien or encumbrance or paid any obligation or liability, absolute or contingent,
other than  current  liabilities  incurred  and paid in the  ordinary  course of
business,  (f) made or guaranteed any loans or advances to any party whatsoever,
(g) suffered or permitted any lien, security interest,  claim,  charge, or other
encumbrance to arise or be granted or created against or upon any of its assets,
real or personal,  tangible or intangible, (h) canceled, waived, or released any
of its  debts,  rights,  or  claims  against  third  parties,  (i)  amended  its
organizational  documents, (j) made or paid any severance or termination payment
to any director, officer, employee, agent, contractor, vendor or consultant, (k)
made any  change  in its  method  of  accounting,  (l) made  any  investment  or
commitment  therefor  in  any  person,   business,   corporation,   association,
partnership,  limited liability company, joint venture,  trust, or other entity,
(m) made, entered into, amended, or terminated any written employment  contract,
created,  made,  amended,  or  terminated  any  bonus,  stock  option,  pension,
retirement,  profit sharing,  or other employee benefit plan or arrangement,  or
withdrawn  from any  "multi-employer  plan" (as defined in the Internal  Revenue
Code of 1986, as amended (the "Code")) so as to create any liability under ERISA
(as  hereinafter  defined) to any person or entity,  (n) amended,  terminated or
experienced a termination of any material contract, agreement, lease, franchise,
or license  to which it is a party,  (o) made any  distributions,  in cash or in
kind, to its  shareholders,  or to any person or entity related to or affiliated
therewith,  in any  capacity,  except  such  distributions  as are  made  in the
ordinary course of the Company's  business  consistent with past practices,  (p)
entered into any other material  transactions  except in the ordinary  course of
business, (q) entered into any contract, commitment, agreement, or understanding
to do any acts described in the foregoing  clauses (a)-(p) of this Section,  (r)
suffered any material  damage,  destruction,  or loss (whether or not covered by
insurance) to any assets,  (s) experienced any strike,  slowdown,  or demand for
recognition by a labor  organization by or with respect to any of its employees,
or (t)  experienced  or effected any  shutdown,  slow-down,  or cessation of any
operations conducted by, or constituting part of, it.

         3.6 Assets;  Licenses,  Permits,  etc.  Except as set forth on Schedule
3.6(a), the Company has good and marketable title to all of its assets, free and
clear  of  all  liens,  security  interests,  claims,  rights  of  another,  and
encumbrances  of any kind  whatsoever.  The  assets of the  Company  are in good
operating  condition and repair,  subject to ordinary wear and tear, taking into
account the  respective  ages of the  properties  involved  and are all that are
necessary for the conduct of the Business. Attached hereto as Schedule 3.6(b) is
a list and description of all federal,  state,  county,  and local  governmental
licenses,  certificates,  certificates of need,  permits,  waivers,  filings and
orders  held or applied  for by the Company and used or relied on (or to be used
or relied on) in  connection  with the  Business  ("Permits").  The  Company has
complied  in all  material  respects,  and the Company is in  compliance  in all
material  respects,  with the  terms  and  conditions  of any such  Permits.  No
additional  Permit  is  required  from  any  federal,  state,  county,  or local
governmental  agency or body  thereof  in  connection  with the  conduct  of the
Business.  No claim has been made by any  governmental  authority  (and,  to the
knowledge of Seller and the Company,  no such claim has been  threatened) to the
effect that a Permit not possessed by the Company is necessary in respect of the
Business.

         3.7      Environmental Issues.

                  (a) For purposes of this  Agreement,  the term  "environmental
laws"  shall  mean  all  laws  and  regulations  relating  to  the  manufacture,
processing,  distribution,  use, treatment,  storage,  disposal,  transport,  or
handling, or the emission, discharge, or release, of any pollutant, contaminant,
chemical,  or industrial  toxic or hazardous  substance or waste,  and any order
related thereto.

                  (b) The Company has complied in all material respects with and
obtained  all  authorizations  and made all filings  required by all  applicable
environmental laws. The properties occupied or used by the Company have not been
contaminated with any hazardous wastes, hazardous substances, or other hazardous
or toxic  materials  in  violation  of any  applicable  environmental  law,  the
violation of which could have a material  adverse  impact on the Business or the
financial position of the Company.

                  (c) The  Company has not  received  any notice from the United
States  Environmental  Protection  Agency that it is a  potentially  responsible
party under the Comprehensive Environmental Response, Compensation and Liability
Act  ("Superfund  Notice"),  any  citation  from  any  federal,  state  or local
governmental  authority for non-compliance with its requirements with respect to
air, water or environmental pollution, or the improper storage, use or discharge
of any  hazardous  waste,  other  waste or  other  substance  or other  material
pertaining to its business  ("Citations") or any written notice from any private
party alleging any such  non-compliance;  and there are no pending or unresolved
Superfund  Notices,  Citations or written notices from private parties  alleging
any such non-compliance.

         3.8  Intellectual  Property Rights.  There are no patents,  trademarks,
trade names, or copyrights, and no applications therefor, owned by or registered
in the name of the Company or in which the Company  has any right,  license,  or
interest.  The  Company  is not a party  to any  license  agreement,  either  as
licensor or licensee, with respect to any patents,  trademarks,  trade names, or
copyrights.  The Company has not received any notice that it is  infringing  any
patent, trademark, trade name, or copyright of others.

         3.9  Compliance  with Laws. To the knowledge of the Company and Seller,
the  Company  has  complied  in all  material  respects,  and the  Company is in
compliance in all material respects,  with all federal, state, county, and local
laws, rules,  regulations and ordinances  currently in effect. No claim has been
made or  threatened  by any  governmental  authority  against the Company to the
effect that the business conducted by the Company fails to comply in any respect
with any law, rule, regulation, or ordinance.

         3.10  Insurance.  Attached  hereto  as  Schedule  3.10 is a list of all
policies of fire, liability, business interruption, and other forms of insurance
(including,  without  limitation,  professional  liability  insurance)  and  all
fidelity  bonds held by or applicable to the Company at any time within the past
three (3) years,  which  schedule  sets forth in respect of each such policy the
policy name, policy number,  carrier, term, type of coverage,  deductible amount
or self-insured retention amount, limits of coverage, and annual premium. To the
knowledge of the Company and Seller,  no event directly  relating to the Company
has occurred  which will result in a retroactive  upward  adjustment of premiums
under any such policies or which is likely to result in any  prospective  upward
adjustment in such premiums.  There have been no material changes in the type of
insurance  coverage  maintained by the Company  during the past three (3) years,
including without  limitation any change which has resulted in any period during
which the Company had no insurance coverage.  Excluding insurance policies which
have  expired and been  replaced,  no  insurance  policy of the Company has been
canceled  within  the last three (3) years and no threat has been made to cancel
any insurance policy of the Company within such period.

         3.11 Employee  Benefit  Matters.  Except as set forth on Schedule 3.11,
the  Company  does not  maintain  nor does it  contribute  nor is it required to
contribute to any "employee welfare benefit plan" (as defined in section 3(1) of
the  Employee  Retirement  Income  Security Act of 1974 (and any sections of the
Code amended by it) and all regulations promulgated thereunder, as the same have
from time to time been amended ("ERISA")) or any "employee pension benefit plan"
(as defined in ERISA).  The Company  does not  presently  maintain and has never
maintained,  or had any  obligation of any nature to  contribute  to, a "defined
benefit plan" within the meaning of the Code.

         3.12 Contracts and  Agreements.  Attached  hereto as Schedule 3.12 is a
list of all written or oral contracts, commitments, leases, and other agreements
(including, without limitation, all promissory notes, loan agreements, and other
evidences  of  indebtedness,  mortgages,  deeds of trust,  security  agreements,
pledge agreements,  service  agreements,  and similar agreements and instruments
and all confidentiality  agreements) to which the Company is a party or by which
the  Company or its  properties  are bound,  pursuant  to which the  obligations
thereunder of any party thereto are, or are contemplated as being, in respect of
any such individual contracts,  commitments,  leases, or other agreements during
any year during the term  thereof,  $25,000 or greater,  or which are  otherwise
material to the Business  (collectively  the  "Contracts"  and  individually,  a
"Contract").  The Company is not and, to the best  knowledge  of the Company and
Seller,  no other party thereto is in default (and no event has occurred  which,
with the passage of time or the giving of notice,  or both,  would  constitute a
default by the Company or, to the best  knowledge of the Company and Seller,  by
any other  party  thereto)  under any  Contract.  The Company has not waived any
material  right under any  Contract,  and no consents or  approvals  (other than
those  obtained in writing and delivered to Prime prior to Closing) are required
under  any  Contract  in  connection  with  the  sale of  Capital  Stock  or the
consummation  of the  transactions  contemplated  hereby.  The  Company  has not
guaranteed any obligation of any other person or entity.

         3.13 Claims and Proceedings. Attached hereto as Schedule 3.13 is a list
and description of all claims, actions, suits,  proceedings,  and investigations
pending or, to the knowledge of the Company and Seller,  threatened  against the
Company,  at law or in  equity,  or before or by any court,  municipal  or other
governmental department,  commission, board, agency, or instrumentality.  Except
as set forth on Schedule 3.13  attached  hereto,  none of such claims,  actions,
suits,  proceedings,  or investigations  will result in any liability or loss to
the Company  which  (individually  or in the  aggregate)  is  material,  and the
Company  has not  been,  and the  Company  is not  now,  subject  to any  order,
judgment,  decree,  stipulation,  or consent of any court, governmental body, or
agency.  No inquiry,  action,  or proceeding has been asserted,  instituted,  or
threatened  against the Company or Seller to restrain or prohibit  the  carrying
out of the  transactions  contemplated  by this  Agreement or to  challenge  the
validity of such  transactions or any part thereof or seeking damages on account
thereof.

         3.14 Taxes.  All federal,  foreign,  state,  county,  and local income,
gross receipts, excise, property,  franchise,  license, sales, use, withholding,
and other tax  (collectively,  "Taxes")  returns,  reports,  and declarations of
estimated tax  (collectively,  "Returns") which were required to be filed by the
company on or before the date hereof have been filed within the time  (including
any  applicable  extensions)  and in the manner  provided  by law,  and all such
Returns are true and correct in all material respects and accurately reflect the
Tax  liabilities  of the Company.  The Company has provided Prime with copies of
all returns  filed for and during the years ended 1998,  1997 and (to the extent
an extension was filed for any return for the year ended 1998) 1996.  All Taxes,
assessments,  penalties,  and  interest  which have become due  pursuant to such
Returns have been paid or adequately  accrued in the Financial  Statements.  The
provisions for Taxes  reflected on the balance sheet  contained in the Financial
Statements are adequate to cover all of the Company's  estimated Tax liabilities
for the respective  periods then ended and all prior periods.  As of the Closing
Date,  the  Company  will not owe any Taxes for any period  prior to the Closing
which  are  not  reflected  on  the  Financial  Statements,   except  for  Taxes
attributable  to the  operations  of the Company  between  June 30, 1999 and the
Closing  Date.  The Company has not executed any presently  effective  waiver or
extension of any statute of limitations  against  assessments  and collection of
Taxes.  There  are  no  pending  or  threatened  claims,  assessments,  notices,
proposals  to assess,  deficiencies,  or audits  (collectively,  "Tax  Actions")
against  the Company  with  respect to any Taxes owed or  allegedly  owed by the
Company. There are no tax liens on any of the assets of the Company.  Proper and
accurate  amounts  have been  withheld  and  remitted by the Company from and in
respect of all persons  from whom it is required by  applicable  law to withhold
for all  periods  in  compliance  with  the tax  withholding  provisions  of all
applicable laws and  regulations.  The Company is not a party to any tax sharing
agreement.

         3.15 Personnel. Attached hereto as Schedule 3.15 is a list of names and
current annual rates of compensation of the officers, employees or agents of the
Company who are necessary  for the operation of the Business (the  "Employees").
Except as set forth on  Schedule  3.15,  there  are no  bonus,  profit  sharing,
percentage  compensation,  company automobile,  club membership,  and other like
benefits,  if any, paid or payable by the Company to any Employees from December
31, 1998 through the Closing Date. Schedule 3.15 attached hereto also contains a
brief   description  of  all  material   terms  of  employment   agreements  and
confidentiality  agreements  to which the  Company is a party and all  severance
benefits which any director,  officer,  Employee or sales  representative of the
Company is or may be  entitled to receive.  The Company has  delivered  to Prime
accurate and complete copies of all such employment agreements,  confidentiality
agreements, and all other agreements,  plans, and other instruments to which the
Company  is a party and under  which  its  employees  are  entitled  to  receive
benefits of any nature.  There is no pending or threatened  (i) labor dispute or
union  organization  campaign  relating to the Company,  (ii) claims against the
Company by any  employees  of the  Company  (other than those  certain  Workers'
Compensation  claims   specifically   described  on  Schedule  3.13),  or  (iii)
terminations,  resignations or retirements of any employees of the Company. None
of  the  employees  of  the  Company  are  represented  by any  labor  union  or
organization. There is no unfair labor practice claim against the Company before
the National Labor Relations Board or any strike, labor dispute,  work slowdown,
or work stoppage pending or threatened against or involving the Company.

         3.16 Business  Relations.  The Company has no reason to believe and has
not been  notified  that any  supplier or customer of the Company  will cease or
refuse  to do  business  with the  Company  in the  same  manner  as  previously
conducted  with the  Company  as a result  of or within  one (1) year  after the
consummation  of  the  transactions  contemplated  hereby,  to the  extent  such
cessation or refusal might affect the Business. The Company has not received any
notice  of any  disruption  (including  delayed  deliveries  or  allocations  by
suppliers) in the availability of the materials or products used by the Company.

         3.17 Working  Capital.  Except as set forth on Schedule  3.17  attached
hereto,  all of  the  accounts,  notes,  and  loans  receivable  (the  "Accounts
Receivable")  reflected in the Financial  Statements,  or arising since June 30,
1999, arose from transactions  occurring in the ordinary course of the Company's
business as previously  conducted,  are bona fide and represent  amounts validly
due,  subject to offsets or  defenses.  Except for  accounts  payable  and other
accrued expenses incurred in the ordinary course of the Company's business since
June 30, 1999 and consistent  with past  practices of the Company,  there are no
liabilities  of  the  Company  other  than  those  reflected  in  the  Financial
Statements.   Adequate  provision  has  been  made  for  uncollectible  Accounts
Receivable.  Since  June 30,  1999,  the  Company  has  collected  its  Accounts
Receivable  and has paid or performed all  liabilities  and  obligations  of the
Company in the ordinary  course,  consistent  with past  practices.  The Working
Capital (as hereinafter  defined) of the Company existing on the Closing Date is
equal to or greater than $100,000.

         3.18 Agents.  Except as set forth on Schedule 3.18 attached hereto, the
Company has not  designated  or appointed  any person  (other than the Company's
employees and officers) or other entity to act for it or on its behalf  pursuant
to any power of attorney or any agency which is presently in effect.

         3.19  Indebtedness To and From Directors,  Officers,  Shareholders  and
Employees.  The Company does not owe any  indebtedness  to any of its directors,
officers, shareholders, employees or affiliates, or have indebtedness owed to it
from any of its  directors,  officers,  shareholders,  employees or  affiliates,
excluding  indebtedness  for travel  advances or similar  advances  for expenses
incurred on behalf of and in the ordinary  course of business of the Company and
consistent with the Company's past  practices.  As of the Effective Time and the
Closing  Date all amounts due the Company from any of its  directors,  officers,
employees or affiliates (or any of their family  members) shall have been repaid
in full.

         3.20 Commission Sales  Contracts.  Except as disclosed in Schedule 3.20
attached hereto,  the Company does not employ or have any relationship  with any
individual,  corporation,  partnership,  or other entity whose compensation from
the Company is in whole or in part determined on a commission basis.

         3.21 Certain  Consents.  Except as set forth on Schedule  3.21 attached
hereto,  there are no consents,  waivers,  or approvals  required to be executed
and/or  obtained  by the  Company  from  third  parties in  connection  with the
execution,  delivery,  and  performance  of this  Agreement  or any of the other
contracts, documents, instruments or agreements to be entered into in connection
with  or as  contemplated  by this  Agreement  (all of  which  are  collectively
referred to as the "Transaction Documents").

         3.22 Brokers.  The Company has not engaged,  or caused any liability to
be incurred to, any finder,  broker,  or sales agent (and has not paid, and will
not pay,  any  finders  fee or  similar  fee or  commission  to any  person)  in
connection with the execution, delivery, or performance of this Agreement or the
transactions contemplated hereby.

         3.23 Interest in Competitors,  Suppliers, and Customers.  Except as set
forth on Schedule 3.23 attached hereto, neither the Company nor any affiliate of
the  Company,  and to the  knowledge  of the Company and  Seller,  no  director,
officer,  employee or affiliate of the Company or any affiliate of any director,
officer, employee or affiliate of the Company, has any ownership interest in any
competitor,  customer or supplier  of the  Company or any  property  used in the
operation of the Business.

         3.24 Warranties.  Except as set forth on Schedule 3.24, the Company has
not made any  warranties  or  guarantees  to third  parties  with respect to any
products  sold or services  rendered by it. Except as set forth on Schedule 3.24
attached hereto, no claims for breach of product or service warranties have been
made against the Company since January 1, 1996.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

     (b) execute and deliver each of the Transaction  Documents to which it is a
party; and

                  (c)  deliver   such  good   standing   certificates,   officer
certificates,  and similar  documents and certificates as counsel for Seller may
reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit B;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  C,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  D,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
the Company,  not  specifically and fully reflected by item and amount on either
Schedule 3.4 or in the  Financial  Statements,  that is or may be asserted  with
respect to any acts or omissions  occurring,  or circumstances  existing,  on or
prior to the Closing  Date,  except for  liabilities  incurred  in the  ordinary
course of business,  or (iii) any obligations or liabilities with respect to any
claims  arising out of actions or omissions,  that occurred prior to the Closing
Date,  by  any of  the  Company's  directors,  officers,  shareholders,  agents,
employees, representatives, subsidiaries and/or affiliates.

                  (b) Seller  agrees to indemnify  and hold harmless each of the
Prime  Indemnified  Parties  from and against any and all  Indemnified  Costs in
connection with the  commencement  or assertion of any third-party  action which
any of the Prime Indemnified  Parties may sustain,  arising out of any breach or
default  by  Seller  of any of its  representations,  warranties,  covenants  or
agreements contained in this Agreement or any Transaction Document.

                  (c) Notwithstanding the foregoing,  no Prime Indemnified Party
shall be entitled to assert any claim for indemnification under this Section 6.1
unless and until such time as all claims of all Prime Indemnified Parties, taken
together,  exceed  $10,000  in the  aggregate,  at which time all claims of such
Prime  Indemnified  Parties  may  be  asserted  individually  or in  combination
(beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section 6.1 shall be limited to the aggregate  Purchase Price received by Seller
under this Agreement,  plus the greater of (a) the value of all remaining equity
interests  which  Seller  holds in the Company at the time of Closing or (b) the
value of all remaining equity interests which Seller holds in the Company at the
time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

         Notwithstanding  the foregoing,  no Seller  Indemnified  Party shall be
entitled to assert any claim for  indemnification  under this Section 7.1 unless
and until such time as all claims of such Seller Indemnified Party, individually
and not in combination with other Seller Indemnified Parties,  exceed $25,000 in
the aggregate,  at which time all claims of such Seller Indemnified Party may be
asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding any transfers governed by Section 9.3), (iii)
relocation  of Seller's  primary  residence  outside of a two hundred (200) mile
radius of the center or facility at which Seller primarily renders services,  or
(iv) if Seller is a physician or other  practicing  licensed  professional,  the
performance by Seller, during any one-month period, of greater than thirty (30%)
of his or her  professional  medical  activities  outside of a two hundred (200)
mile radius of the center or facility  primarily utilized by Seller prior to the
date  of  this  Agreement;  the  Seller's  executor,   administrator,   trustee,
custodian,   receiver   or  other   legal  or   personal   representative   (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or relocation of primary residence or practice, as the case may be, within which
time  it may  require  that  the  Company  purchase  (subject  to the  remaining
provisions  of this  subsection)  all of Seller's  capital stock of the Company,
upon the terms and conditions  hereinafter  set forth,  by giving notice of such
election in writing to the  Company.  The Company  may, in its sole  discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

         9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital Contributions.  Without in any way limiting or
qualifying  the  representation  and warranty  with  respect to Working  Capital
contained in Section 3.17, all parties to this Agreement  acknowledge  and agree
that no  shareholder  of the  Company,  or any other party,  has any  obligation
existing on the Closing Date to make a capital contribution to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                  IN ADDITION, SHARES MAY BE TRANSFERRED ONLY IN COMPLIANCE WITH
                  CERTAIN  CONDITIONS  SPECIFIED  IN A  CERTAIN  STOCK  PURCHASE
                  AGREEMENT  DATED EFFECTIVE AS OF SEPTEMBER 1, 1999, A COMPLETE
                  AND CORRECT COPY OF WHICH IS AVAILABLE  FOR  INSPECTION AT THE
                  PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE  FURNISHED TO THE
                  HOLDER HEREOF UPON WRITTEN REQUEST AND WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Invalid Provisions.  If any provision of this Agreement is held to
be  illegal,  invalid,  or  unenforceable  under  present or future  laws,  such
provision shall be fully severable, this Agreement shall be construed as if such
illegal,  invalid, or unenforceable provision had never comprised a part of this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                           1301 Capital of Texas Highway
                                 Suite C-300
                                 Austin, Texas 78746
                                 Attention: President

with a copy to:                  Mr. Timothy L. LaFrey
                                 Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                 816 Congress Avenue, Suite 1900
                                 Austin, Texas 78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Mark R. Mandel, M.D., Trustee
                                under Trust Agreement
                                dated April 12, 1989
                                680 Brewer Road
                                Hillsborough, California   94010

     Each party may change its  address for  purposes of this  Section by proper
notice to the other parties.

     10.7 Survival of Representations,  Warranties, and Covenants. Regardless of
any investigation at any time made by or on behalf of any party hereto or of any
information any party may have in respect  thereof,  all covenants,  agreements,
representations,  and  warranties  made  hereunder  or  pursuant  hereto  or  in
connection with the transactions contemplated hereby shall survive the Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within the actual  knowledge  of the  officers  of the Company
holding office immediately prior to the Closing, and any employee of the Company
who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>

                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President

Seller:                                  /s/ Mark R. Mandel, M.D.

                                            Printed Name:  Mark R. Mandel, M.D.
                                                Trustee under Trust Agreement
                                                dated April 12, 1989

Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President

<PAGE>

                                TABLE OF EXHIBITS

EXHIBIT A:        Financial Statements
EXHIBIT B:        Form of Exclusive Use Agreement
EXHIBIT C:        Form of Assignment and Security Agreement
EXHIBIT D:        Form of Amended and Restated Bylaws of Seller

<PAGE>
                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.

                           --------------------------

                                       and

                           Horizon Vision Center, Inc.

                              --------------------

                             Dated September 1, 1999

<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision  Center,  Inc.,  a Nevada  corporation  (the  "Company")  and  Bradley J.
Sandler,   M.D.  an  individual  residing  in  Suisun  City,  California  and  a
shareholder of the Company ("Seller").

The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
44,780  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock  certificate  number C-97
(collectively,  the "Capital  Stock").  The purchase price for the Capital Stock
shall be $507,933.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

            Representations and Warranties of the Company and Seller

         Seller and the Company hereby  represent and warrant to Prime,  jointly
and  severally,  that each of the  following  matters is true and correct in all
respects as of the Closing  Date (with the  understanding  that Prime is relying
materially  on each  such  representation  and  warranty  in  entering  into and
performing this Agreement),  which  representations and warranties shall also be
deemed  made as of the  Effective  Time and which  shall  survive  the  Closing;
provided,  however,  that all  representations  and  warranties  made by  Seller
hereunder shall be deemed made by Seller only to the actual knowledge of Seller.

         3.1 Due  Organization.  The Company is a  corporation  duly  organized,
validly existing, and in good standing under the laws of the State of Nevada and
has full power and  authority to carry on its business as now  conducted  and as
proposed to be conducted. The Company is qualified to do business and is in good
standing  in the states set forth on  Schedule  3.1(a)  attached  hereto,  which
states represent every jurisdiction where such qualification is required for the
conduct of the Company's business as conducted on the Closing Date. Complete and
correct copies of the Company's Articles of Incorporation,  Bylaws, all board of
directors'  resolutions,  all  shareholders'  resolutions,  and  all  amendments
thereto,  have been  delivered to Prime.  Schedule  3.1(b) sets forth a true and
complete  list,  as of the Closing  Date, of all of the holders of any equity or
other ownership interest in the Company or of any right to obtain, by conversion
or otherwise,  and regardless of whether  presently  exercisable,  any equity or
other  ownership  interest in the  Company;  in each case showing the number and
type of interest  or right held.  Schedule  3.1(b) also  identifies  each of the
persons  listed   therein  that  is  a  physician  or  other  licensed   medical
professional,  and describes  each such  person's  license(s)  and  professional
title. Except as set forth on Schedule 3.1(b),  immediately prior to the Closing
Date there are outstanding (i) no shares of equity or other voting securities of
the Company,  (ii) no securities of the Company convertible into or exchangeable
for shares of equity or other voting securities of the Company, (iii) no options
or other rights to acquire from the Company or Seller,  and no obligation of the
Company or Seller to issue or sell, any equity or other voting securities of the
Company or any securities of the Company  convertible  into or exchangeable  for
such equity or voting securities,  and (iv) no equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar  rights of or with respect to the Company.  Immediately  following
the Closing of this transaction and the closings of the Related Acquisitions (as
hereinafter  defined),  Prime will own sixty  percent (60%) of all of the voting
equity  securities of the Company (after  assuming the  conversion,  exchange or
exercise of any and all securities or rights  convertible  into, or exchangeable
or exercisable for, voting equity  securities of the Company),  and all of those
persons and entities listed on Schedule 3.1(b) will own, in the aggregate, forty
percent  (40%) of all of the voting  equity  securities  of the  Company  (after
assuming  the  conversion,  exchange or exercise  of any and all  securities  or
rights  convertible  into, or  exchangeable  or exercisable  for,  voting equity
securities of the Company).  The Capital Stock transferred by Seller to Prime at
the Closing,  as well as all other capital stock of the Company  transferred  to
Prime in the Related Acquisitions,  will be duly authorized,  validly issued and
outstanding,  fully  paid,  non-assessable,  and free of any  liens,  claims  or
encumbrances whatsoever.

         3.2  Subsidiaries.  Except as set  forth on  Schedule  3.2  (reflecting
ownership  interests  and the nature of such  interests),  the Company  does not
directly or indirectly  have (or possess any options or other rights to acquire)
any  subsidiaries or any direct or indirect  ownership  interests in any person,
business,  corporation,  partnership,  limited liability  company,  association,
joint venture, trust, or other entity.

         3.3 Due  Authorization.  Each of the  Company and Seller has full power
and  authority to enter into and perform  this  Agreement  and each  Transaction
Document  required  to be  executed  by the  Company  or  Seller  in  connection
herewith.  The execution,  delivery,  and performance of this Agreement and each
such  Transaction  Document has been duly authorized by all necessary  action of
the Company,  its directors,  its officers and its shareholders.  This Agreement
and each such  Transaction  Document  has been  duly and  validly  executed  and
delivered  by the  Company  and  Seller  and  constitutes  a valid  and  binding
obligation  of the  Company  and  Seller,  enforceable  against  each of them in
accordance  with its terms.  The execution,  delivery,  and  performance of this
Agreement,  and each  Transaction  Document  required  herein to be  executed by
Seller  and/or the Company do not (a) violate any  federal,  state,  county,  or
local law,  rule,  or  regulation  applicable  to the Company,  the Business (as
hereinafter defined),  the Company's assets or the Capital Stock, (b) violate or
conflict with, or permit the cancellation of, any agreement to which the Company
is a party,  or by which the Company or its properties  are bound,  or result in
the creation of any lien, security interest,  charge, or encumbrance upon any of
such  properties or the upon the Capital Stock,  (c) permit the  acceleration of
the maturity of any  indebtedness of Seller or the Company,  or any indebtedness
secured by the Capital  Stock or by the property of the Company,  or (d) violate
or conflict with any provision of the  organizational  documents of the Company.
No action,  consent,  waiver or approval of, or filing with, any federal, state,
county or local  governmental  authority is required by Seller or the Company in
connection  with the execution,  delivery,  or performance of this Agreement (or
any Transaction Document).

         3.4  Financial  Statements.  The  unaudited  balance  sheet and  income
statement  of the  Company as of and for each of the years  ended March 31, 1998
and 1999, and the unaudited balance sheet and income statement of the Company as
of and for  the  three  (3)  months  ended  June  30,  1999  (collectively,  the
"Financial  Statements")  are  attached  hereto  as  Exhibit  A.  The  Financial
Statements have been prepared in accordance with generally  accepted  accounting
principles  consistently  applied ("GAAP") (except as specifically noted therein
or in Schedule  3.4) and fairly  present the  financial  position and results of
operations  of the  Company  as of the  indicated  dates  and for the  indicated
periods.  Except for liabilities  incurred in the ordinary course of business or
disclosed  in  Schedule  3.4,  and except to the extent  specifically  and fully
reflected in the Financial Statements  (including the notes thereto),  as of the
Closing Date, the Company has no claims,  debts,  liabilities,  or  obligations,
whether known or unknown, absolute,  contingent or otherwise (including, but not
limited to,  federal,  state,  and local taxes,  any sales taxes,  use taxes and
property  taxes,  any taxes arising from the  transactions  contemplated by this
Agreement and any liabilities arising from any litigation or civil,  criminal or
regulatory  proceeding  involving or related to the  Company,  its assets or the
Business).  The  Company and Seller each agree to  indemnify  and hold  harmless
Prime  and its  affiliates  from and  against  any and all such  claims,  debts,
liabilities and obligations.  Except as set forth in Schedule 3.4 hereto,  since
June 30,  1999 there has been no  material  adverse  change in the assets of the
Company, the Business, or the results of operations or financial position of the
Company.

         3.5 Conduct of Business;  Certain Actions.  As used herein,  "Business"
means all of the business  conducted  by the  Company,  which shall be deemed to
include  all  refractive  surgery  modalities,  now  performed,  offered or made
available, including, without limitation,  implantable contact lenses, instromal
corneal  rings,  laser  in  situs  keratomileusis  photorefractive  keratectomy,
automated lemellar  keratoplasty,  radial keratotomy,  astigmatic keratotomy and
similar procedures.  Except as set forth on Schedule 3.5 attached hereto,  since
June 30, 1999,  the Company has  conducted  its Business and  operations  of the
Business in the ordinary  course and consistent  with its past practices and has
not (a)  purchased  or retired  any  indebtedness,  or  purchased,  retired,  or
redeemed any  ownership  interest  from,  any  director,  officer,  shareholder,
employee or affiliate of the Company,  or engaged in any other  transaction that
involves or requires  distributions of money or other assets from the Company to
any director, officer, shareholder, employee or affiliate of the Company if such
other  transaction  is not done in the  ordinary  course of business  and is not
consistent with past practices of the Company, (b) increased the compensation of
any  directors,  officers,  employees,  agents,  contractors,  vendors  or other
parties,  except for wage and salary  increases  made in the ordinary  course of
business and consistent with the past practices of the Company, (c) made capital
expenditures  exceeding  $10,000  individually or $25,000 in the aggregate,  (d)
sold any asset (or any group of related assets) in any transaction (or series of
related  transactions)  in which the purchase price or book value for such asset
(or group of related assets) exceeded  $10,000,  (e) discharged or satisfied any
lien or encumbrance or paid any obligation or liability, absolute or contingent,
other than  current  liabilities  incurred  and paid in the  ordinary  course of
business,  (f) made or guaranteed any loans or advances to any party whatsoever,
(g) suffered or permitted any lien, security interest,  claim,  charge, or other
encumbrance to arise or be granted or created against or upon any of its assets,
real or personal,  tangible or intangible, (h) canceled, waived, or released any
of its  debts,  rights,  or  claims  against  third  parties,  (i)  amended  its
organizational  documents, (j) made or paid any severance or termination payment
to any director, officer, employee, agent, contractor, vendor or consultant, (k)
made any  change  in its  method  of  accounting,  (l) made  any  investment  or
commitment  therefor  in  any  person,   business,   corporation,   association,
partnership,  limited liability company, joint venture,  trust, or other entity,
(m) made, entered into, amended, or terminated any written employment  contract,
created,  made,  amended,  or  terminated  any  bonus,  stock  option,  pension,
retirement,  profit sharing,  or other employee benefit plan or arrangement,  or
withdrawn  from any  "multi-employer  plan" (as defined in the Internal  Revenue
Code of 1986, as amended (the "Code")) so as to create any liability under ERISA
(as  hereinafter  defined) to any person or entity,  (n) amended,  terminated or
experienced a termination of any material contract, agreement, lease, franchise,
or license  to which it is a party,  (o) made any  distributions,  in cash or in
kind, to its  shareholders,  or to any person or entity related to or affiliated
therewith,  in any  capacity,  except  such  distributions  as are  made  in the
ordinary course of the Company's  business  consistent with past practices,  (p)
entered into any other material  transactions  except in the ordinary  course of
business, (q) entered into any contract, commitment, agreement, or understanding
to do any acts described in the foregoing  clauses (a)-(p) of this Section,  (r)
suffered any material  damage,  destruction,  or loss (whether or not covered by
insurance) to any assets,  (s) experienced any strike,  slowdown,  or demand for
recognition by a labor  organization by or with respect to any of its employees,
or (t)  experienced  or effected any  shutdown,  slow-down,  or cessation of any
operations conducted by, or constituting part of, it.

         3.6 Assets;  Licenses,  Permits,  etc.  Except as set forth on Schedule
3.6(a), the Company has good and marketable title to all of its assets, free and
clear  of  all  liens,  security  interests,  claims,  rights  of  another,  and
encumbrances  of any kind  whatsoever.  The  assets of the  Company  are in good
operating  condition and repair,  subject to ordinary wear and tear, taking into
account the  respective  ages of the  properties  involved  and are all that are
necessary for the conduct of the Business. Attached hereto as Schedule 3.6(b) is
a list and description of all federal,  state,  county,  and local  governmental
licenses,  certificates,  certificates of need,  permits,  waivers,  filings and
orders  held or applied  for by the Company and used or relied on (or to be used
or relied on) in  connection  with the  Business  ("Permits").  The  Company has
complied  in all  material  respects,  and the Company is in  compliance  in all
material  respects,  with the  terms  and  conditions  of any such  Permits.  No
additional  Permit  is  required  from  any  federal,  state,  county,  or local
governmental  agency or body  thereof  in  connection  with the  conduct  of the
Business.  No claim has been made by any  governmental  authority  (and,  to the
knowledge of Seller and the Company,  no such claim has been  threatened) to the
effect that a Permit not possessed by the Company is necessary in respect of the
Business.

         3.7      Environmental Issues.

                  (a) For purposes of this  Agreement,  the term  "environmental
laws"  shall  mean  all  laws  and  regulations  relating  to  the  manufacture,
processing,  distribution,  use, treatment,  storage,  disposal,  transport,  or
handling, or the emission, discharge, or release, of any pollutant, contaminant,
chemical,  or industrial  toxic or hazardous  substance or waste,  and any order
related thereto.

                  (b) The Company has complied in all material respects with and
obtained  all  authorizations  and made all filings  required by all  applicable
environmental laws. The properties occupied or used by the Company have not been
contaminated with any hazardous wastes, hazardous substances, or other hazardous
or toxic  materials  in  violation  of any  applicable  environmental  law,  the
violation of which could have a material  adverse  impact on the Business or the
financial position of the Company.

                  (c) The  Company has not  received  any notice from the United
States  Environmental  Protection  Agency that it is a  potentially  responsible
party under the Comprehensive Environmental Response, Compensation and Liability
Act  ("Superfund  Notice"),  any  citation  from  any  federal,  state  or local
governmental  authority for non-compliance with its requirements with respect to
air, water or environmental pollution, or the improper storage, use or discharge
of any  hazardous  waste,  other  waste or  other  substance  or other  material
pertaining to its business  ("Citations") or any written notice from any private
party alleging any such  non-compliance;  and there are no pending or unresolved
Superfund  Notices,  Citations or written notices from private parties  alleging
any such non-compliance.

         3.8  Intellectual  Property Rights.  There are no patents,  trademarks,
trade names, or copyrights, and no applications therefor, owned by or registered
in the name of the Company or in which the Company  has any right,  license,  or
interest.  The  Company  is not a party  to any  license  agreement,  either  as
licensor or licensee, with respect to any patents,  trademarks,  trade names, or
copyrights.  The Company has not received any notice that it is  infringing  any
patent, trademark, trade name, or copyright of others.

         3.9  Compliance  with Laws. To the knowledge of the Company and Seller,
the  Company  has  complied  in all  material  respects,  and the  Company is in
compliance in all material respects,  with all federal, state, county, and local
laws, rules,  regulations and ordinances  currently in effect. No claim has been
made or  threatened  by any  governmental  authority  against the Company to the
effect that the business conducted by the Company fails to comply in any respect
with any law, rule, regulation, or ordinance.

         3.10  Insurance.  Attached  hereto  as  Schedule  3.10 is a list of all
policies of fire, liability, business interruption, and other forms of insurance
(including,  without  limitation,  professional  liability  insurance)  and  all
fidelity  bonds held by or applicable to the Company at any time within the past
three (3) years,  which  schedule  sets forth in respect of each such policy the
policy name, policy number,  carrier, term, type of coverage,  deductible amount
or self-insured retention amount, limits of coverage, and annual premium. To the
knowledge of the Company and Seller,  no event directly  relating to the Company
has occurred  which will result in a retroactive  upward  adjustment of premiums
under any such policies or which is likely to result in any  prospective  upward
adjustment in such premiums.  There have been no material changes in the type of
insurance  coverage  maintained by the Company  during the past three (3) years,
including without  limitation any change which has resulted in any period during
which the Company had no insurance coverage.  Excluding insurance policies which
have  expired and been  replaced,  no  insurance  policy of the Company has been
canceled  within  the last three (3) years and no threat has been made to cancel
any insurance policy of the Company within such period.

         3.11 Employee  Benefit  Matters.  Except as set forth on Schedule 3.11,
the  Company  does not  maintain  nor does it  contribute  nor is it required to
contribute to any "employee welfare benefit plan" (as defined in section 3(1) of
the  Employee  Retirement  Income  Security Act of 1974 (and any sections of the
Code amended by it) and all regulations promulgated thereunder, as the same have
from time to time been amended ("ERISA")) or any "employee pension benefit plan"
(as defined in ERISA).  The Company  does not  presently  maintain and has never
maintained,  or had any  obligation of any nature to  contribute  to, a "defined
benefit plan" within the meaning of the Code.

         3.12 Contracts and  Agreements.  Attached  hereto as Schedule 3.12 is a
list of all written or oral contracts, commitments, leases, and other agreements
(including, without limitation, all promissory notes, loan agreements, and other
evidences  of  indebtedness,  mortgages,  deeds of trust,  security  agreements,
pledge agreements,  service  agreements,  and similar agreements and instruments
and all confidentiality  agreements) to which the Company is a party or by which
the  Company or its  properties  are bound,  pursuant  to which the  obligations
thereunder of any party thereto are, or are contemplated as being, in respect of
any such individual contracts,  commitments,  leases, or other agreements during
any year during the term  thereof,  $25,000 or greater,  or which are  otherwise
material to the Business  (collectively  the  "Contracts"  and  individually,  a
"Contract").  The Company is not and, to the best  knowledge  of the Company and
Seller,  no other party thereto is in default (and no event has occurred  which,
with the passage of time or the giving of notice,  or both,  would  constitute a
default by the Company or, to the best  knowledge of the Company and Seller,  by
any other  party  thereto)  under any  Contract.  The Company has not waived any
material  right under any  Contract,  and no consents or  approvals  (other than
those  obtained in writing and delivered to Prime prior to Closing) are required
under  any  Contract  in  connection  with  the  sale of  Capital  Stock  or the
consummation  of the  transactions  contemplated  hereby.  The  Company  has not
guaranteed any obligation of any other person or entity.

         3.13 Claims and Proceedings. Attached hereto as Schedule 3.13 is a list
and description of all claims, actions, suits,  proceedings,  and investigations
pending or, to the knowledge of the Company and Seller,  threatened  against the
Company,  at law or in  equity,  or before or by any court,  municipal  or other
governmental department,  commission, board, agency, or instrumentality.  Except
as set forth on Schedule 3.13  attached  hereto,  none of such claims,  actions,
suits,  proceedings,  or investigations  will result in any liability or loss to
the Company  which  (individually  or in the  aggregate)  is  material,  and the
Company  has not  been,  and the  Company  is not  now,  subject  to any  order,
judgment,  decree,  stipulation,  or consent of any court, governmental body, or
agency.  No inquiry,  action,  or proceeding has been asserted,  instituted,  or
threatened  against the Company or Seller to restrain or prohibit  the  carrying
out of the  transactions  contemplated  by this  Agreement or to  challenge  the
validity of such  transactions or any part thereof or seeking damages on account
thereof.

         3.14 Taxes.  All federal,  foreign,  state,  county,  and local income,
gross receipts, excise, property,  franchise,  license, sales, use, withholding,
and other tax  (collectively,  "Taxes")  returns,  reports,  and declarations of
estimated tax  (collectively,  "Returns") which were required to be filed by the
company on or before the date hereof have been filed within the time  (including
any  applicable  extensions)  and in the manner  provided  by law,  and all such
Returns are true and correct in all material respects and accurately reflect the
Tax  liabilities  of the Company.  The Company has provided Prime with copies of
all returns  filed for and during the years ended 1998,  1997 and (to the extent
an extension was filed for any return for the year ended 1998) 1996.  All Taxes,
assessments,  penalties,  and  interest  which have become due  pursuant to such
Returns have been paid or adequately  accrued in the Financial  Statements.  The
provisions for Taxes  reflected on the balance sheet  contained in the Financial
Statements are adequate to cover all of the Company's  estimated Tax liabilities
for the respective  periods then ended and all prior periods.  As of the Closing
Date,  the  Company  will not owe any Taxes for any period  prior to the Closing
which  are  not  reflected  on  the  Financial  Statements,   except  for  Taxes
attributable  to the  operations  of the Company  between  June 30, 1999 and the
Closing  Date.  The Company has not executed any presently  effective  waiver or
extension of any statute of limitations  against  assessments  and collection of
Taxes.  There  are  no  pending  or  threatened  claims,  assessments,  notices,
proposals  to assess,  deficiencies,  or audits  (collectively,  "Tax  Actions")
against  the Company  with  respect to any Taxes owed or  allegedly  owed by the
Company. There are no tax liens on any of the assets of the Company.  Proper and
accurate  amounts  have been  withheld  and  remitted by the Company from and in
respect of all persons  from whom it is required by  applicable  law to withhold
for all  periods  in  compliance  with  the tax  withholding  provisions  of all
applicable laws and  regulations.  The Company is not a party to any tax sharing
agreement.

         3.15 Personnel. Attached hereto as Schedule 3.15 is a list of names and
current annual rates of compensation of the officers, employees or agents of the
Company who are necessary  for the operation of the Business (the  "Employees").
Except as set forth on  Schedule  3.15,  there  are no  bonus,  profit  sharing,
percentage  compensation,  company automobile,  club membership,  and other like
benefits,  if any, paid or payable by the Company to any Employees from December
31, 1998 through the Closing Date. Schedule 3.15 attached hereto also contains a
brief   description  of  all  material   terms  of  employment   agreements  and
confidentiality  agreements  to which the  Company is a party and all  severance
benefits which any director,  officer,  Employee or sales  representative of the
Company is or may be  entitled to receive.  The Company has  delivered  to Prime
accurate and complete copies of all such employment agreements,  confidentiality
agreements, and all other agreements,  plans, and other instruments to which the
Company  is a party and under  which  its  employees  are  entitled  to  receive
benefits of any nature.  There is no pending or threatened  (i) labor dispute or
union  organization  campaign  relating to the Company,  (ii) claims against the
Company by any  employees  of the  Company  (other than those  certain  Workers'
Compensation  claims   specifically   described  on  Schedule  3.13),  or  (iii)
terminations,  resignations or retirements of any employees of the Company. None
of  the  employees  of  the  Company  are  represented  by any  labor  union  or
organization. There is no unfair labor practice claim against the Company before
the National Labor Relations Board or any strike, labor dispute,  work slowdown,
or work stoppage pending or threatened against or involving the Company.

         3.16 Business  Relations.  The Company has no reason to believe and has
not been  notified  that any  supplier or customer of the Company  will cease or
refuse  to do  business  with the  Company  in the  same  manner  as  previously
conducted  with the  Company  as a result  of or within  one (1) year  after the
consummation  of  the  transactions  contemplated  hereby,  to the  extent  such
cessation or refusal might affect the Business. The Company has not received any
notice  of any  disruption  (including  delayed  deliveries  or  allocations  by
suppliers) in the availability of the materials or products used by the Company.

         3.17 Working  Capital.  Except as set forth on Schedule  3.17  attached
hereto,  all of  the  accounts,  notes,  and  loans  receivable  (the  "Accounts
Receivable")  reflected in the Financial  Statements,  or arising since June 30,
1999, arose from transactions  occurring in the ordinary course of the Company's
business as previously  conducted,  are bona fide and represent  amounts validly
due,  subject to offsets or  defenses.  Except for  accounts  payable  and other
accrued expenses incurred in the ordinary course of the Company's business since
June 30, 1999 and consistent  with past  practices of the Company,  there are no
liabilities  of  the  Company  other  than  those  reflected  in  the  Financial
Statements.   Adequate  provision  has  been  made  for  uncollectible  Accounts
Receivable.  Since  June 30,  1999,  the  Company  has  collected  its  Accounts
Receivable  and has paid or performed all  liabilities  and  obligations  of the
Company in the ordinary  course,  consistent  with past  practices.  The Working
Capital (as hereinafter  defined) of the Company existing on the Closing Date is
equal to or greater than $100,000.

         3.18 Agents.  Except as set forth on Schedule 3.18 attached hereto, the
Company has not  designated  or appointed  any person  (other than the Company's
employees and officers) or other entity to act for it or on its behalf  pursuant
to any power of attorney or any agency which is presently in effect.

         3.19  Indebtedness To and From Directors,  Officers,  Shareholders  and
Employees.  The Company does not owe any  indebtedness  to any of its directors,
officers, shareholders, employees or affiliates, or have indebtedness owed to it
from any of its  directors,  officers,  shareholders,  employees or  affiliates,
excluding  indebtedness  for travel  advances or similar  advances  for expenses
incurred on behalf of and in the ordinary  course of business of the Company and
consistent with the Company's past  practices.  As of the Effective Time and the
Closing  Date all amounts due the Company from any of its  directors,  officers,
employees or affiliates (or any of their family  members) shall have been repaid
in full.

         3.20 Commission Sales  Contracts.  Except as disclosed in Schedule 3.20
attached hereto,  the Company does not employ or have any relationship  with any
individual,  corporation,  partnership,  or other entity whose compensation from
the Company is in whole or in part determined on a commission basis.

         3.21 Certain  Consents.  Except as set forth on Schedule  3.21 attached
hereto,  there are no consents,  waivers,  or approvals  required to be executed
and/or  obtained  by the  Company  from  third  parties in  connection  with the
execution,  delivery,  and  performance  of this  Agreement  or any of the other
contracts, documents, instruments or agreements to be entered into in connection
with  or as  contemplated  by this  Agreement  (all of  which  are  collectively
referred to as the "Transaction Documents").

         3.22 Brokers.  The Company has not engaged,  or caused any liability to
be incurred to, any finder,  broker,  or sales agent (and has not paid, and will
not pay,  any  finders  fee or  similar  fee or  commission  to any  person)  in
connection with the execution, delivery, or performance of this Agreement or the
transactions contemplated hereby.

         3.23 Interest in Competitors,  Suppliers, and Customers.  Except as set
forth on Schedule 3.23 attached hereto, neither the Company nor any affiliate of
the  Company,  and to the  knowledge  of the Company and  Seller,  no  director,
officer,  employee or affiliate of the Company or any affiliate of any director,
officer, employee or affiliate of the Company, has any ownership interest in any
competitor,  customer or supplier  of the  Company or any  property  used in the
operation of the Business.

         3.24 Warranties.  Except as set forth on Schedule 3.24, the Company has
not made any  warranties  or  guarantees  to third  parties  with respect to any
products  sold or services  rendered by it. Except as set forth on Schedule 3.24
attached hereto, no claims for breach of product or service warranties have been
made against the Company since January 1, 1996.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

     (b) execute and deliver each of the Transaction  Documents to which it is a
party; and

                  (c)  deliver   such  good   standing   certificates,   officer
certificates,  and similar  documents and certificates as counsel for Seller may
reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit B;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  C,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  D,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
the Company,  not  specifically and fully reflected by item and amount on either
Schedule 3.4 or in the  Financial  Statements,  that is or may be asserted  with
respect to any acts or omissions  occurring,  or circumstances  existing,  on or
prior to the Closing  Date,  except for  liabilities  incurred  in the  ordinary
course of business,  or (iii) any obligations or liabilities with respect to any
claims  arising out of actions or omissions,  that occurred prior to the Closing
Date,  by  any of  the  Company's  directors,  officers,  shareholders,  agents,
employees, representatives, subsidiaries and/or affiliates.

                  (b) Seller  agrees to indemnify  and hold harmless each of the
Prime  Indemnified  Parties  from and against any and all  Indemnified  Costs in
connection with the  commencement  or assertion of any third-party  action which
any of the Prime Indemnified  Parties may sustain,  arising out of any breach or
default  by  Seller  of any of its  representations,  warranties,  covenants  or
agreements contained in this Agreement or any Transaction Document.

                  (c) Notwithstanding the foregoing,  no Prime Indemnified Party
shall be entitled to assert any claim for indemnification under this Section 6.1
unless and until such time as all claims of all Prime Indemnified Parties, taken
together,  exceed  $10,000  in the  aggregate,  at which time all claims of such
Prime  Indemnified  Parties  may  be  asserted  individually  or in  combination
(beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section 6.1 shall be limited to the aggregate  Purchase Price received by Seller
under this Agreement,  plus the greater of (a) the value of all remaining equity
interests  which  Seller  holds in the Company at the time of Closing or (b) the
value of all remaining equity interests which Seller holds in the Company at the
time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

         Notwithstanding  the foregoing,  no Seller  Indemnified  Party shall be
entitled to assert any claim for  indemnification  under this Section 7.1 unless
and until such time as all claims of such Seller Indemnified Party, individually
and not in combination with other Seller Indemnified Parties,  exceed $25,000 in
the aggregate,  at which time all claims of such Seller Indemnified Party may be
asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding any transfers governed by Section 9.3), (iii)
relocation  of Seller's  primary  residence  outside of a two hundred (200) mile
radius of the center or facility at which Seller primarily renders services,  or
(iv) if Seller is a physician or other  practicing  licensed  professional,  the
performance by Seller, during any one-month period, of greater than thirty (30%)
of his or her  professional  medical  activities  outside of a two hundred (200)
mile radius of the center or facility  primarily utilized by Seller prior to the
date  of  this  Agreement;  the  Seller's  executor,   administrator,   trustee,
custodian,   receiver   or  other   legal  or   personal   representative   (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or relocation of primary residence or practice, as the case may be, within which
time  it may  require  that  the  Company  purchase  (subject  to the  remaining
provisions  of this  subsection)  all of Seller's  capital stock of the Company,
upon the terms and conditions  hereinafter  set forth,  by giving notice of such
election in writing to the  Company.  The Company  may, in its sole  discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

         9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital Contributions.  Without in any way limiting or
qualifying  the  representation  and warranty  with  respect to Working  Capital
contained in Section 3.17, all parties to this Agreement  acknowledge  and agree
that no  shareholder  of the  Company,  or any other party,  has any  obligation
existing on the Closing Date to make a capital contribution to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                  IN ADDITION, SHARES MAY BE TRANSFERRED ONLY IN COMPLIANCE WITH
                  CERTAIN  CONDITIONS  SPECIFIED  IN A  CERTAIN  STOCK  PURCHASE
                  AGREEMENT  DATED EFFECTIVE AS OF SEPTEMBER 1, 1999, A COMPLETE
                  AND CORRECT COPY OF WHICH IS AVAILABLE  FOR  INSPECTION AT THE
                  PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE  FURNISHED TO THE
                  HOLDER HEREOF UPON WRITTEN REQUEST AND WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Invalid Provisions.  If any provision of this Agreement is held to
be  illegal,  invalid,  or  unenforceable  under  present or future  laws,  such
provision shall be fully severable, this Agreement shall be construed as if such
illegal,  invalid, or unenforceable provision had never comprised a part of this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                           1301 Capital of Texas Highway
                                 Suite C-300
                                 Austin, Texas 78746
                                 Attention: President

with a copy to:                  Mr. Timothy L. LaFrey
                                 Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                 816 Congress Avenue, Suite 1900
                                 Austin, Texas 78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Bradley J. Sandler, M.D.
                                403 Calle De Caballo
                                Suisun City, CA   94585-1501

     Each party may change its  address for  purposes of this  Section by proper
notice to the other parties.

     10.7 Survival of Representations,  Warranties, and Covenants. Regardless of
any investigation at any time made by or on behalf of any party hereto or of any
information any party may have in respect  thereof,  all covenants,  agreements,
representations,  and  warranties  made  hereunder  or  pursuant  hereto  or  in
connection with the transactions contemplated hereby shall survive the Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within the actual  knowledge  of the  officers  of the Company
holding office immediately prior to the Closing, and any employee of the Company
who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]

<PAGE>
                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title:Secretary & Manager

Seller:                                  /s/ Bradley J. Sandler, M.D.

                                         Printed Name:  Bradley J. Sandler, M.D.

Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President

<PAGE>

                                TABLE OF EXHIBITS

EXHIBIT A:        Financial Statements
EXHIBIT B:        Form of Exclusive Use Agreement
EXHIBIT C:        Form of Assignment and Security Agreement
EXHIBIT D:        Form of Amended and Restated Bylaws of Seller

<PAGE>

                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.

                           --------------------------

                                       and

                           Horizon Vision Center, Inc.

                              --------------------

                             Dated September 1, 1999

<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada corporation (the "Company") and D. Brent Reed and
Carellyn S. Reed, individuals residing in Folsom, California shareholders of the
Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
73,520  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock  certificate  number C-25
and C-94 (collectively, the "Capital Stock"). The purchase price for the Capital
Stock shall be $833,926.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing  this Agreement and each of the other
contracts, documents, instruments or agreements to be entered into in connection
with or as  contemplated  by  this  Agreement,  all of  which  are  collectively
referred to as the "Transaction Documents"):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                    Representations and Warranties of Seller

         Seller  hereby  represents  and  warrants  to  Prime  that  each of the
following  matters is true and correct in all  respects  as of the Closing  Date
(with  the  understanding   that  Prime  is  relying  materially  on  each  such
representation  and warranty in entering into and  performing  this  Agreement),
which  representations  and  warranties  shall  also  be  deemed  made as of the
Effective Time and which shall survive the Closing:

         3.1 Due  Authorization.  Seller has full power and  authority  to enter
into and perform this  Agreement and each  Transaction  Document  required to be
executed  by  Seller  in  connection  herewith.  This  Agreement  and each  such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     3.2 Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be free of any liens, claims or encumbrances whatsoever.

         3.3 Ownership.  Immediately  following the Closing Date,  except as set
forth on  Schedule  3.3,  Seller  does not own (i) any shares of equity or other
voting securities of the Company, (ii) any securities of the Company convertible
into or  exchangeable  for shares of equity or other  voting  securities  of the
Company,  (iii) any options or other rights to acquire from the Company,  or any
obligation of the Company to issue or sell, equity or other voting securities of
the Company,  or securities of the Company  convertible into or exchangeable for
such equity or voting securities, and (iv) any equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar rights of or with respect to the Company.

         3.4 Claims and Proceedings.  No inquiry, action, or proceeding has been
asserted,  instituted,  or threatened against Seller to restrain or prohibit the
carrying out of the transactions  contemplated by this Agreement or to challenge
the  validity of such  transactions  or any part  thereof or seeking  damages on
account thereof.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which it is a party; and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit A;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  B,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  C,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of any  breach or  default  by Seller or the  Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified  Parties may sustain,  arising out of any breach or default by
Seller  of any of  its  representations,  warranties,  covenants  or  agreements
contained in this Agreement or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement,  plus the greater of (a) the value of all remaining
equity interests which Seller holds in the Company at the time of Closing or (b)
the value of all remaining equity interests which Seller holds in the Company at
the time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding  any  transfers  governed by Section 9.3), or
(iii) the performance by Seller,  during any one-month  period,  of greater than
thirty  (30%) of his or her  professional  medical  activities  outside of a two
hundred (200) mile radius of the center or facility primarily utilized by Seller
prior to the  date of this  Agreement;  the  Seller's  executor,  administrator,
trustee,  custodian,  receiver or other legal or  personal  representative  (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or shift in the geographical  location of Seller's practice, as the case may be,
within  which time it may  require  that the  Company  purchase  (subject to the
remaining  provisions of this  subsection) all of Seller's  capital stock of the
Company,  upon the terms and conditions  hereinafter set forth, by giving notice
of such election in writing to Company. The Company may, in its sole discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital  Contributions.  All parties to this Agreement
acknowledge  and agree that no shareholder  of the Company,  or any other party,
has any obligation  existing on the Closing Date to make a capital  contribution
to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                           IN  ADDITION,  SHARES  MAY  BE  TRANSFERRED  ONLY  IN
                  COMPLIANCE  WITH  CERTAIN  CONDITIONS  SPECIFIED  IN A CERTAIN
                  STOCK PURCHASE  AGREEMENT  DATED  EFFECTIVE AS OF SEPTEMBER 1,
                  1999, A COMPLETE  AND CORRECT  COPY OF WHICH IS AVAILABLE  FOR
                  INSPECTION AT THE PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE
                  FURNISHED  TO THE  HOLDER  HEREOF  UPON  WRITTEN  REQUEST  AND
                  WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4  Severability.  If any  provision of this  Agreement is held to be
illegal,  invalid, or unenforceable under present or future laws, such provision
shall be fully severable,  this Agreement shall be construed as if such illegal,
invalid,  or  unenforceable  provision  had  never  comprised  a  part  of  this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         D. Brent Reed and Carellyn S. Reed
                                157 Cascade Falls Drive
                                Folsom, California   95630

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge" is used in this Agreement in reference to Prime,  it shall
mean such  items as are  within  the actual  knowledge  of Ken  Shifrin,  Cheryl
Williams, Mark Rosenberg and Dr. Jenkins.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

10.12 Counterparts. This Agreement may be executed in several counterparts, each
of which shall constitute an original and all of which together shall constitute
one and the same  instrument.  Any party  hereto may execute  this  Agreement by
signing any one counterpart.

                            [Signature page follows]

<PAGE>
                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President

Seller:                                  /s/ D. Brent Reed

                                         Printed Name:   D. Brent Reed

                                         /s/ Carellyn S. Reed

                                         Printed Name:  Carellyn S. Reed

Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President

<PAGE>

                                TABLE OF EXHIBITS

EXHIBIT A:                 Form of Exclusive Use Agreement

EXHIBIT B:                 Form of Assignment and Security Agreement

EXHIBIT C:                 Form of Amended and Restated Bylaws of Seller

<PAGE>

                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.

                           --------------------------

                                       and

                           Horizon Vision Center, Inc.

                              --------------------

                             Dated September 1, 1999

<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the  "Company") and Severin Family
Trust, and shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
39,369  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock certificate  number C-27,
C-35, C-40, and C-45 (collectively, the "Capital Stock"). The purchase price for
the Capital Stock shall be $446,557.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing  this Agreement and each of the other
contracts, documents, instruments or agreements to be entered into in connection
with or as  contemplated  by  this  Agreement,  all of  which  are  collectively
referred to as the "Transaction Documents"):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                    Representations and Warranties of Seller

         Seller  hereby  represents  and  warrants  to  Prime  that  each of the
following  matters is true and correct in all  respects  as of the Closing  Date
(with  the  understanding   that  Prime  is  relying  materially  on  each  such
representation  and warranty in entering into and  performing  this  Agreement),
which  representations  and  warranties  shall  also  be  deemed  made as of the
Effective Time and which shall survive the Closing:

         3.1 Due  Authorization.  Seller has full power and  authority  to enter
into and perform this  Agreement and each  Transaction  Document  required to be
executed  by  Seller  in  connection  herewith.  This  Agreement  and each  such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     3.2 Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be free of any liens, claims or encumbrances whatsoever.

         3.3 Ownership.  Immediately  following the Closing Date,  except as set
forth on  Schedule  3.3,  Seller  does not own (i) any shares of equity or other
voting securities of the Company, (ii) any securities of the Company convertible
into or  exchangeable  for shares of equity or other  voting  securities  of the
Company,  (iii) any options or other rights to acquire from the Company,  or any
obligation of the Company to issue or sell, equity or other voting securities of
the Company,  or securities of the Company  convertible into or exchangeable for
such equity or voting securities, and (iv) any equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar rights of or with respect to the Company.

         3.4 Claims and Proceedings.  No inquiry, action, or proceeding has been
asserted,  instituted,  or threatened against Seller to restrain or prohibit the
carrying out of the transactions  contemplated by this Agreement or to challenge
the  validity of such  transactions  or any part  thereof or seeking  damages on
account thereof.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which it is a party; and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit A;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  B,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  C,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of any  breach or  default  by Seller or the  Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified  Parties may sustain,  arising out of any breach or default by
Seller  of any of  its  representations,  warranties,  covenants  or  agreements
contained in this Agreement or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement,  plus the greater of (a) the value of all remaining
equity interests which Seller holds in the Company at the time of Closing or (b)
the value of all remaining equity interests which Seller holds in the Company at
the time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding  any  transfers  governed by Section 9.3), or
(iii) the performance by Seller,  during any one-month  period,  of greater than
thirty  (30%) of his or her  professional  medical  activities  outside of a two
hundred (200) mile radius of the center or facility primarily utilized by Seller
prior to the  date of this  Agreement;  the  Seller's  executor,  administrator,
trustee,  custodian,  receiver or other legal or  personal  representative  (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or shift in the geographical  location of Seller's practice, as the case may be,
within  which time it may  require  that the  Company  purchase  (subject to the
remaining  provisions of this  subsection) all of Seller's  capital stock of the
Company,  upon the terms and conditions  hereinafter set forth, by giving notice
of such election in writing to Company. The Company may, in its sole discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital  Contributions.  All parties to this Agreement
acknowledge  and agree that no shareholder  of the Company,  or any other party,
has any obligation  existing on the Closing Date to make a capital  contribution
to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                           IN  ADDITION,  SHARES  MAY  BE  TRANSFERRED  ONLY  IN
                  COMPLIANCE  WITH  CERTAIN  CONDITIONS  SPECIFIED  IN A CERTAIN
                  STOCK PURCHASE  AGREEMENT  DATED  EFFECTIVE AS OF SEPTEMBER 1,
                  1999, A COMPLETE  AND CORRECT  COPY OF WHICH IS AVAILABLE  FOR
                  INSPECTION AT THE PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE
                  FURNISHED  TO THE  HOLDER  HEREOF  UPON  WRITTEN  REQUEST  AND
                  WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4  Severability.  If any  provision of this  Agreement is held to be
illegal,  invalid, or unenforceable under present or future laws, such provision
shall be fully severable,  this Agreement shall be construed as if such illegal,
invalid,  or  unenforceable  provision  had  never  comprised  a  part  of  this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Severin Family Trust
                                Sanford L. Severin, Trustee
                                1040 McCauley Road
                                Danville, California   94526

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge" is used in this Agreement in reference to Prime,  it shall
mean such  items as are  within  the actual  knowledge  of Ken  Shifrin,  Cheryl
Williams, Mark Rosenberg and Dr. Jenkins.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

10.12 Counterparts. This Agreement may be executed in several counterparts, each
of which shall constitute an original and all of which together shall constitute
one and the same  instrument.  Any party  hereto may execute  this  Agreement by
signing any one counterpart.

                            [Signature page follows]

<PAGE>

                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President

Seller:                                  /s/ Sanford L. Severin
                                         Printed Name:   Sanford L. Severin,
                                                Trustee under the Sevenin
                                                Family Trust

Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President

<PAGE>

                                TABLE OF EXHIBITS

EXHIBIT A:                 Form of Exclusive Use Agreement

EXHIBIT B:                 Form of Assignment and Security Agreement

EXHIBIT C:                 Form of Amended and Restated Bylaws of Seller

<PAGE>

                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.

                           --------------------------

                                       and

                           Horizon Vision Center, Inc.

                              --------------------

                             Dated September 1, 1999

<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the "Company") and the Stephen and
Andrea Turner Family Trust, a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement, Prime agrees to purchase from Seller, as of the Effective Time, 7,920
authorized  and issued  shares of the  Company's  $0.01 par value  common  stock
presently  owned by Seller and  evidenced by stock  certificate  number C-28 and
C-38  (collectively,  the "Capital  Stock").  The purchase price for the Capital
Stock shall be $131,004.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing  this Agreement and each of the other
contracts, documents, instruments or agreements to be entered into in connection
with or as  contemplated  by  this  Agreement,  all of  which  are  collectively
referred to as the "Transaction Documents"):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                    Representations and Warranties of Seller

         Seller  hereby  represents  and  warrants  to  Prime  that  each of the
following  matters is true and correct in all  respects  as of the Closing  Date
(with  the  understanding   that  Prime  is  relying  materially  on  each  such
representation  and warranty in entering into and  performing  this  Agreement),
which  representations  and  warranties  shall  also  be  deemed  made as of the
Effective Time and which shall survive the Closing:

         3.1 Due  Authorization.  Seller has full power and  authority  to enter
into and perform this  Agreement and each  Transaction  Document  required to be
executed  by  Seller  in  connection  herewith.  This  Agreement  and each  such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     3.2 Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be free of any liens, claims or encumbrances whatsoever.

         3.3 Ownership.  Immediately  following the Closing Date,  except as set
forth on  Schedule  3.3,  Seller  does not own (i) any shares of equity or other
voting securities of the Company, (ii) any securities of the Company convertible
into or  exchangeable  for shares of equity or other  voting  securities  of the
Company,  (iii) any options or other rights to acquire from the Company,  or any
obligation of the Company to issue or sell, equity or other voting securities of
the Company,  or securities of the Company  convertible into or exchangeable for
such equity or voting securities, and (iv) any equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar rights of or with respect to the Company.

         3.4 Claims and Proceedings.  No inquiry, action, or proceeding has been
asserted,  instituted,  or threatened against Seller to restrain or prohibit the
carrying out of the transactions  contemplated by this Agreement or to challenge
the  validity of such  transactions  or any part  thereof or seeking  damages on
account thereof.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which it is a party; and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit A;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  B,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  C,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of any  breach or  default  by Seller or the  Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified  Parties may sustain,  arising out of any breach or default by
Seller  of any of  its  representations,  warranties,  covenants  or  agreements
contained in this Agreement or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement,  plus the greater of (a) the value of all remaining
equity interests which Seller holds in the Company at the time of Closing or (b)
the value of all remaining equity interests which Seller holds in the Company at
the time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding  any  transfers  governed by Section 9.3), or
(iii) the performance by Seller,  during any one-month  period,  of greater than
thirty  (30%) of his or her  professional  medical  activities  outside of a two
hundred (200) mile radius of the center or facility primarily utilized by Seller
prior to the  date of this  Agreement;  the  Seller's  executor,  administrator,
trustee,  custodian,  receiver or other legal or  personal  representative  (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or shift in the geographical  location of Seller's practice, as the case may be,
within  which time it may  require  that the  Company  purchase  (subject to the
remaining  provisions of this  subsection) all of Seller's  capital stock of the
Company,  upon the terms and conditions  hereinafter set forth, by giving notice
of such election in writing to Company. The Company may, in its sole discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital  Contributions.  All parties to this Agreement
acknowledge  and agree that no shareholder  of the Company,  or any other party,
has any obligation  existing on the Closing Date to make a capital  contribution
to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                           IN  ADDITION,  SHARES  MAY  BE  TRANSFERRED  ONLY  IN
                  COMPLIANCE  WITH  CERTAIN  CONDITIONS  SPECIFIED  IN A CERTAIN
                  STOCK PURCHASE  AGREEMENT  DATED  EFFECTIVE AS OF SEPTEMBER 1,
                  1999, A COMPLETE  AND CORRECT  COPY OF WHICH IS AVAILABLE  FOR
                  INSPECTION AT THE PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE
                  FURNISHED  TO THE  HOLDER  HEREOF  UPON  WRITTEN  REQUEST  AND
                  WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4  Severability.  If any  provision of this  Agreement is held to be
illegal,  invalid, or unenforceable under present or future laws, such provision
shall be fully severable,  this Agreement shall be construed as if such illegal,
invalid,  or  unenforceable  provision  had  never  comprised  a  part  of  this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Stephen and Andrea Turner Family Trust
                                250 Stonewall Road
                                Berkeley, California   94705

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge" is used in this Agreement in reference to Prime,  it shall
mean such  items as are  within  the actual  knowledge  of Ken  Shifrin,  Cheryl
Williams, Mark Rosenberg and Dr. Jenkins.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

10.12 Counterparts. This Agreement may be executed in several counterparts, each
of which shall constitute an original and all of which together shall constitute
one and the same  instrument.  Any party  hereto may execute  this  Agreement by
signing any one counterpart.

                            [Signature page follows]

<PAGE>
                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President

Seller:                                  /s/ Stephen G. Turner, M.D.
                                         /s/ Andrea J. Turner
                                        Printed Name:   Stephen G. Turner, M.D.,
                                                Trustee under the Stephen and
                                                Andrea Turner Family Trust
                                                Andrea J. Turner, Trustee

Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President

<PAGE>

                                TABLE OF EXHIBITS

EXHIBIT A:                 Form of Exclusive Use Agreement

EXHIBIT B:                 Form of Assignment and Security Agreement

EXHIBIT C:                 Form of Amended and Restated Bylaws of Seller

<PAGE>

                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.

                           --------------------------

                                       and

                           Horizon Vision Center, Inc.

                              --------------------

                             Dated September 1, 1999

<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the  "Company") and Medical Vision
Technology  Profit,  Sharing Plan for the benefit of Stephen  Wilmarth,  M.D., a
shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
13,876  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock  certificate  number C-31
(collectively,  the "Capital  Stock").  The purchase price for the Capital Stock
shall be $157,393.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing  this Agreement and each of the other
contracts, documents, instruments or agreements to be entered into in connection
with or as  contemplated  by  this  Agreement,  all of  which  are  collectively
referred to as the "Transaction Documents"):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                    Representations and Warranties of Seller

         Seller  hereby  represents  and  warrants  to  Prime  that  each of the
following  matters is true and correct in all  respects  as of the Closing  Date
(with  the  understanding   that  Prime  is  relying  materially  on  each  such
representation  and warranty in entering into and  performing  this  Agreement),
which  representations  and  warranties  shall  also  be  deemed  made as of the
Effective Time and which shall survive the Closing:

         3.1 Due  Authorization.  Seller has full power and  authority  to enter
into and perform this  Agreement and each  Transaction  Document  required to be
executed  by  Seller  in  connection  herewith.  This  Agreement  and each  such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     3.2 Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be free of any liens, claims or encumbrances whatsoever.

         3.3 Ownership.  Immediately  following the Closing Date,  except as set
forth on  Schedule  3.3,  Seller  does not own (i) any shares of equity or other
voting securities of the Company, (ii) any securities of the Company convertible
into or  exchangeable  for shares of equity or other  voting  securities  of the
Company,  (iii) any options or other rights to acquire from the Company,  or any
obligation of the Company to issue or sell, equity or other voting securities of
the Company,  or securities of the Company  convertible into or exchangeable for
such equity or voting securities, and (iv) any equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar rights of or with respect to the Company.

         3.4 Claims and Proceedings.  No inquiry, action, or proceeding has been
asserted,  instituted,  or threatened against Seller to restrain or prohibit the
carrying out of the transactions  contemplated by this Agreement or to challenge
the  validity of such  transactions  or any part  thereof or seeking  damages on
account thereof.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which it is a party; and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit A;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  B,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  C,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of any  breach or  default  by Seller or the  Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified  Parties may sustain,  arising out of any breach or default by
Seller  of any of  its  representations,  warranties,  covenants  or  agreements
contained in this Agreement or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement,  plus the greater of (a) the value of all remaining
equity interests which Seller holds in the Company at the time of Closing or (b)
the value of all remaining equity interests which Seller holds in the Company at
the time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding  any  transfers  governed by Section 9.3), or
(iii) the performance by Seller,  during any one-month  period,  of greater than
thirty  (30%) of his or her  professional  medical  activities  outside of a two
hundred (200) mile radius of the center or facility primarily utilized by Seller
prior to the  date of this  Agreement;  the  Seller's  executor,  administrator,
trustee,  custodian,  receiver or other legal or  personal  representative  (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or shift in the geographical  location of Seller's practice, as the case may be,
within  which time it may  require  that the  Company  purchase  (subject to the
remaining  provisions of this  subsection) all of Seller's  capital stock of the
Company,  upon the terms and conditions  hereinafter set forth, by giving notice
of such election in writing to Company. The Company may, in its sole discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital  Contributions.  All parties to this Agreement
acknowledge  and agree that no shareholder  of the Company,  or any other party,
has any obligation  existing on the Closing Date to make a capital  contribution
to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                           IN  ADDITION,  SHARES  MAY  BE  TRANSFERRED  ONLY  IN
                  COMPLIANCE  WITH  CERTAIN  CONDITIONS  SPECIFIED  IN A CERTAIN
                  STOCK PURCHASE  AGREEMENT  DATED  EFFECTIVE AS OF SEPTEMBER 1,
                  1999, A COMPLETE  AND CORRECT  COPY OF WHICH IS AVAILABLE  FOR
                  INSPECTION AT THE PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE
                  FURNISHED  TO THE  HOLDER  HEREOF  UPON  WRITTEN  REQUEST  AND
                  WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4  Severability.  If any  provision of this  Agreement is held to be
illegal,  invalid, or unenforceable under present or future laws, such provision
shall be fully severable,  this Agreement shall be construed as if such illegal,
invalid,  or  unenforceable  provision  had  never  comprised  a  part  of  this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578

Seller:                         Medical Vision Technology Profit Sharing Plan
                                FBO Stephen Wilmarth, M.D.
                                9824 Carlton Court
                                Granite Bay, California   95746

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge" is used in this Agreement in reference to Prime,  it shall
mean such  items as are  within  the actual  knowledge  of Ken  Shifrin,  Cheryl
Williams, Mark Rosenberg and Dr. Jenkins.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

10.12 Counterparts. This Agreement may be executed in several counterparts, each
of which shall constitute an original and all of which together shall constitute
one and the same  instrument.  Any party  hereto may execute  this  Agreement by
signing any one counterpart.

                            [Signature page follows]

<PAGE>
                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President

Seller:                                  /s/ Stephen Wilmarth, M.D.
                                        Printed Name:   Stephen Wilmarth, M.D.,
                                                Trustee under the Medical Vision
                                                Technology Profit Sharing Plan,
                                                for the benefit of Stephen
                                                Wilmarth, M.D.

Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President

<PAGE>

                                TABLE OF EXHIBITS

EXHIBIT A:                 Form of Exclusive Use Agreement

EXHIBIT B:                 Form of Assignment and Security Agreement

EXHIBIT C:                 Form of Amended and Restated Bylaws of Seller

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