LIMITED LIABILITY COMPANY AGREEMENT

                     OF PRIME REFRACTIVE - St. Louis, 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 - St. Louis, 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,  L.L.C., a Delaware limited  liability  company  ("Prime"),
Kirk P. Morey, M.D. and Sean Mulqueeny, O.D. 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.

                                   ARTICLE II.

                                   MEMBERSHIP

     Section 2.1.  Members'  Interests.  As used herein,  "Membership  Interest"
shall refer to a percentage  membership interest of the Company.  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 vote of  Members  holding  a  majority  of the  Membership
Interests.  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.  The Membership  Interests
are  transferable  only with the unanimous  written consent of Prime (or Prime's
permitted  designee).  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.

         Section 2.6. Resignation of Members. A Member may not withdraw from the
Company except on the written consent of Prime (or Prime's permitted  designee).
The terms of the Member's  withdrawal  shall be determined by agreement  between
the  withdrawing  Member and the  remaining  Members  holding a majority  of the
Membership  Interests  (excluding  the  Membership  Interest of 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 Members having not less than the minimum votes that would be necessary
to authorize or take such action at a meeting at which all Membership  Interests
were present and voted, 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 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, Joe Jenkins,  M.D., and Brad Hummel, David D. Dulaney,  M.D.,
and Mark  Rosenberg.  Thereafter,  the  Managers  shall be  elected  or  removed
pursuant  to the vote or written  consent of Members  holding a majority  of the
Membership  Interests.  A  Manager  shall  serve as a  Manager  until his or her
earlier  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.  Members holding a majority of the Membership
Interests shall be entitled to designate the successor thereto.

         Section 8.3.  Removal of Managers.  Any Manager may be removed,  for or
without  cause,  at any time,  but only by  Members  holding a  majority  of the
Membership  Interests.  Members  holding a majority of the Membership  Interests
shall be entitled to designate the successor thereto.

         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 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.

         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,  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.

         The foregoing paragraph notwithstanding, the Managers shall establish a
Medical  Executive  Committee,  the  size  and  composition  of  which  shall be
established by resolution passed by the affirmative vote of not less than eighty
percent (80%) of the Managers.  The Medical Executive  Committee shall initially
consist of the  following  three (3) members:  David D. Dulaney,  M.D.,  Kirk P.
Morey, M.D. and Sean Mulqueeny,  O.D. Members of the Medical Executive Committee
must be licensed physicians or optometrists,  but need not be Members, Managers,
or officers of the Company.  The Medical Executive  Committee shall meet at such
time or times as it may, by majority  vote of its  members,  elect and may adopt
procedures  for the conduct of its  meetings.  The Medical  Executive  Committee
shall have  authority  and  control  over the medical  aspects of the  Company's
business,  and shall  provide  advice to the Managers on  decisions  relating to
equipment   purchases,    technological    obsolescence,    quality   assurance,
credentialing, and such other matters as shall be requested by the Managers. The
Medical  Executive  Committee  shall have the authority to bind the Company only
with respect to the medical aspects of the Company's business.  Unless otherwise
established by a resolution adopted by at least a majority of the members of the
Medical  Executive  Committee,  the  majority  of the  members  of  the  Medical
Executive Committee shall constitute a quorum of the transaction of its business
and the affirmative vote of the majority of the members of the Medical Executive
Committee shall constitute action validly taken by that body.

         Section 8.11.  Compensation of Managers. The Managers may be reimbursed
for reasonable actual expenses incurred in connection with the management of the
Company,   but  Managers  shall  not  otherwise  be   compensated   unless  such
compensation is agreed upon in advance by all Members.

         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.  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;  Brad  Hummel,
President;  Cheryl  Williams,  Vice  President,  Secretary  and Chief  Financial
Officer;  Teena Belcik, Vice President and Treasurer;  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.

                                  ARTICLE XII.

                             NO OVERHEAD ALLOCATIONS

         No Member  shall be  entitled  to  allocate to the Company any costs or
expenses  that are paid or incurred by any Member or its  affiliates  (excluding
the Company).

                                  ARTICLE XIII.

                                  MISCELLANEOUS

     Section 13.1. Fiscal Year. The fiscal year of the Company shall be fixed by
resolution of the Managers.

     Section 13.2.  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 13.3. 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 13.4. 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 13.5. 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 13.6.  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  13.7.  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 13.8.  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 13.9. 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 XIV.

                                   AMENDMENTS

         Section 14.1.  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 14.2. 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>


S-1

                                SIGNATURE PAGE TO

                       LIMITED LIABILITY COMPANY AGREEMENT

                     OF PRIME REFRACTIVE - St. Louis, L.L.C.

         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 June, 2000.

                                               Kirk P. Morey, M.D.





                                               Sean Mulqueeny, O.D.



                                               Prime Refractive, L.L.C.



                                               Cheryl Williams, Vice President


<PAGE>


A-1

                                    EXHIBIT A

                               OWNERSHIP INTERESTS

Name                                                   Ownership Percentage

Prime Refractive, L.L.C.                                     90%


Sean Mulqueeny, O.D.                                          5%