Document:

CONTRIBUTION AGREEMENT

                                      AMONG

                               PRIME MBC, L.L.C.,

                          MBC HOLDING COMPANY, L.L.C.,

                         MANN BERKELEY EYE CENTER, P.A.,

                            PAUL MICHAEL MANN, M.D.,

                            RALPH G. BERKELEY, M.D.,

                            MICHAEL B. CAPLAN, M.D.,

                               MARK F. MICHELETTI

                                       AND

                                 PRIME RVC, INC.

                               DATED March 1, 2000

<PAGE>

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043838.0000  AUSTIN 161222 v11

043838.0000  AUSTIN 161222 v11
                             CONTRIBUTION AGREEMENT

         This  Contribution  Agreement (this  "Agreement") is entered into to be
effective as of March 1, 2000 (the "Effective  Time"),  among Prime RVC, Inc., a
Delaware corporation ("Prime"),  Prime MBC, L.L.C., a Delaware limited liability
company  ("Newco"),  MBC Holding  Company,  L.L.C.,  a Texas  limited  liability
company ("Target Center"),  Mann Berkeley Eye Center, P.A., a Texas professional
association ("MBEC"), Paul Michael Mann, M.D. ("Mann"),  Ralph G. Berkeley, M.D.
("Berkeley"),  Michael  B.  Caplan,  M.D.  ("Caplan")  and  Mark  F.  Micheletti
("Micheletti").  Target Center, Mann,  Berkeley,  Caplan and Micheletti are also
sometimes referred to collectively herein as the "Sellers" and individually as a
"Seller".  Mann, Berkeley and Caplan are also sometimes referred to collectively
herein as the "Physicians" and individually as the "Physician".

         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,  (a) Prime agrees to purchase,  as of the Effective Time, from Target
Center,  an  undivided  sixty  percent  (60%)  interest  in (i) the  Assets  (as
hereinafter defined) and (ii) the business conducted using the Assets, excluding
the practice of medicine in all cases (the  "Business"),  for $3,765,000 in cash
(the  "Purchase  Price"),  together with  warrants,  in  substantially  the form
attached  hereto  as  Exhibit A (the  "Warrants"),  entitling  Target  Center to
purchase  27,000  shares  of $0.01  par  value  common  stock  of Prime  Medical
Services,  Inc., a Delaware corporation ("PMSI"); (b) Prime agrees to contribute
to Newco,  as of the Effective  Time, the undivided sixty percent (60%) interest
in the Assets and Business  purchased by Prime, and will receive a sixty percent
(60%) ownership interest in Newco; (c) Target Center agrees to contribute, as of
the Effective Time, the remaining  undivided forty percent (40%) interest in the
Assets and Business to Newco. The Purchase Price will be allocated to the Assets
in accordance with Schedule 1.1 attached hereto. The parties agree that:

         (y) immediately prior to the Closing, all of the outstanding membership
interests of Newco shall be owned by Target Center,  and,  immediately after the
Closing,  Prime  shall  own  sixty  percent  (60%)  of all  of  the  outstanding
membership  interests of Newco,  and Target Center shall own forty percent (40%)
of all of the outstanding membership interests of Newco; and

         (z) prior to the  Effective  Time,  Prime and Target  Center shall have
executed the limited liability company agreement, in the form attached hereto as
Exhibit B, and any other organizational documents of Newco;

         The  organizational  documents  of Newco are  hereinafter  collectively
referred to as the "Organizational Documents".

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  Assets.  The term  "Assets"  shall mean the items  listed on  Schedule  1.3
attached hereto, all Permits (as hereinafter  defined),  all business records of
Refractive  Surgery (as hereinafter  defined) and the Business,  Working Capital
(as defined in Section 3.17) of at least $25,000,  all contract rights of Target
Center under leases  (including rights to receive returns of deposits under such
leases) or contracts listed on Schedule 1.3 and all of the business and goodwill
of Refractive  Surgery and the Business.  Each of the Sellers hereby  represents
and warrants that the Assets include all of the equipment, instruments, computer
software used in connection  with the  equipment,  Permits,  personal  property,
furniture,  business  records  and other  assets of Target  Center that are used
primarily in or are materially  relied on for the conduct of Refractive  Surgery
and the Business by the Target Center.  Notwithstanding  any provision contained
herein to the  contrary,  the term "Assets" and  "Business"  shall only refer to
those  assets or  business  utilized in or related to the  operations  of Target
Center in Austin,  Texas. As used in this Agreement,  "Refractive Surgery" shall
mean,  collectively,  any current and/or future surgical  procedures intended to
correct refractive error,  including,  without  limitation,  myopia,  hyperopia,
presbyopia or astigmatism of the eye. Notwithstanding anything in this Agreement
to the contrary,  "Refractive  Surgery" shall not include any specific procedure
that, at the time the procedure is to be performed,  is required in the exercise
of a physician's independent professional judgment as to the individual patient,
to be performed in an operating  room  approved by the American  Association  of
Ambulatory  Surgical  Centers or Joint Commission on Accreditation of Healthcare
Organizations (or any similar or successor accreditation board or body) with the
capability of general  anesthesia,  in each instance within either an ambulatory
surgical center or acute care hospital that is, in either case,  licensed by the
State of Texas  (provided,  however,  that this sentence shall not in the future
exclude from  "Refractive  Surgery" any surgical  procedure that was included in
the  definition  of  "Refractive  Surgery"  at the  Effective  Time,  and if any
applicable  future  regulatory  change  occurs  that  would  result  in  such  a
reclassification,   the  parties  to  this   Agreement  will  work  together  to
restructure  the  operating  mechanics  of their  relationship  in a manner that
allows the operations of the Business to comply with such regulatory  change and
also preserves the economic benefits of the parties arising under this Agreement
and  the  other  Transaction  Documents).  Notwithstanding  the  foregoing,  the
following shall not be "Assets" and shall be retained by Target Center:

(a)      all activities that constitute the practice of medicine;

(b)      the books of account and record books of Target  Center  (complete  and
         accurate copies of which, insofar as they relate to the Business during
         the  calendar  years 1998 and 1999,  shall be  provided  to Prime on or
         before the Closing Date);

(c)      Target Center's rights under this Agreement; and

(d)  assets  that are  neither  used in,  nor  relied  on for,  the  conduct  of
     Refractive Surgery.

1.4 Assumed  Liabilities.  At the  Closing,  Newco shall only assume those trade
payables on open  account  incurred in the  ordinary  course of Target  Center's
business since February 1, 2000 from unrelated parties.  Such limited assumption
shall be pursuant to that certain general conveyance, assignment and transfer of
assets  and  assumption  of  liabilities,  attached  hereto  as  Exhibit  C (the
"Assignment and Assumption Agreement") to be executed by Newco, Prime and Target
Center at the Closing,  effective as of the Effective  Time. With respect to any
lease or other contract obligations reflected on Schedule 1.4, it is agreed that
Newco  will only be  assuming  obligations  thereunder  which  accrue  after the
Effective Time, and will have no  responsibility  whatsoever for any breaches or
defaults which occurred prior to the Closing Date, or for  obligations  accruing
prior to the  Effective  Time.  Except  for those  liabilities  and  obligations
specifically assumed by Newco as provided above, any and all debts, liabilities,
and obligations of Target Center, 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
Target Center or its business)  shall remain the sole  responsibility  of Target
Center  and  Target  Center  covenants  to  pay  promptly  all  such  debts  and
liabilities and to fulfill all such obligations as and when the same become due.
Notwithstanding  any provision of this Agreement,  Newco and Prime do not assume
any debts,  obligations or liabilities of Target Center  whatsoever,  except for
those trade payables described in the first sentence of this Section.

1.5  Payment of Purchase Price.  The Purchase Price shall be paid in immediately
     available funds at the Closing.

ARTICLE II

                     Representations and Warranties of Prime

         Prime represents and warrants to the Sellers that each of the following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that the Sellers are 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 corporation 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 a  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  other  agreement,  instrument  and
document required to be executed by Prime in connection herewith. This Agreement
and each  other  agreement,  instrument,  and  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 other agreement, instrument, and 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  agreement,  instrument or other  document  executed in
connection herewith by Prime).

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.

2.5      Investment Representations.  Prime:
         --------------------------

(a)      Is an "accredited investor," and has not retained or consulted with any
         "purchaser  representative"  (as such terms are  defined in Rule 501 of
         Regulation D promulgated  under the  Securities Act of 1933, as amended
         (the  "Securities  Act"))  in  connection  with its  execution  of this
         Agreement and the consummation of the transactions contemplated hereby;

(b)  Has such knowledge and experience in financial and business matters that it
     is capable of evaluating the merits and risks of an investment in Newco;

(c)  Will acquire any Newco interests for its own account for investment and not
     with the view  toward  resale or  redistribution  in a manner  which  would
     require registration under the Securities Act, the Texas Securities Act, as
     amended,  or the  securities  laws of any  other  state,  and it  does  not
     presently have any reason to anticipate any change in its  circumstances or
     other  particular  occasion or event which would cause it to sell its Newco
     interests,  or any part thereof or interest therein,  and it has no present
     intention  of dividing  the Newco  interests  with others or  reselling  or
     otherwise  disposing of the Newco interests or any part thereof or interest
     therein  either  currently or after the passage of a fixed or  determinable
     amount of time or upon the occurrence or nonoccurrence of any predetermined
     event or circumstance;

(d)      In connection  with entering  into this  Agreement and the  Transaction
         Documents  to  which  it is a  party,  and  in  making  the  investment
         decisions associated  therewith,  it has neither received nor relied on
         any  representations  or  warranties  from  Newco,  the  Sellers,   the
         affiliates of the foregoing or the officers,  directors,  shareholders,
         employees,   partners,  members,  agents,  consultants,   personnel  or
         similarly  related  parties of any of the  foregoing,  other than those
         representations and warranties contained in this Agreement;

(e)      Is  able to bear  the  economic  risk  of an  investment  in the  Newco
         interests  and it has  sufficient  net  worth to  sustain a loss of its
         entire  investment  without material  economic  hardship if such a loss
         should occur; and

(f)      Acknowledges  that the Newco interests have not been  registered  under
         the Securities  Act, or the securities laws of any of the states of the
         United  States,  that an investment in the Newco  interests  involves a
         high  degree of risk,  and that the  Newco  interests  are an  illiquid
         investment.

         2.6 Securities  Laws  Compliance.  Prime shall remain  responsible  for
assuring that Newco complies with all securities  laws,  both state and federal,
and that Newco makes all necessary  disclosures  as required by such  securities
laws.

ARTICLE III

                    Representations and Warranties of Sellers

         The Sellers each,  jointly and severally,  hereby represent and warrant
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  Organization.  Target  Center  is a  limited  liability  company  duly
organized, validly existing, and in good standing under the laws of the State of
Texas and has full power and authority to carry on its business as now conducted
and as proposed to be conducted.  Mann, Berkeley,  Caplan and Micheletti are the
only owners of Target Center, and their respective  ownership  interests are set
forth on Schedule  3.1.  No other  person or entity has any right to acquire any
ownership interest in Target Center. Complete and correct copies of the Articles
of  Organization,  the Regulations,  all managers'  resolutions and all members'
resolutions of Target Center, and all amendments thereto, have been delivered to
Prime.  Target Center is qualified to do business and is in good standing in the
states set forth on Schedule 3.1 attached  hereto,  which states represent every
jurisdiction  where such  qualification  is  required  for the conduct of Target
Center's business as conducted on the Closing Date.

3.2 Subsidiaries. Target Center 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 Seller has full power and  authority to enter into
and perform this Agreement and each other  agreement,  instrument,  and document
required to be executed by such Seller in connection  herewith.  The  execution,
delivery,   and  performance  of  this  Agreement  and  such  other  agreements,
instruments,  and documents have been duly authorized by all necessary action of
Target  Center,  its managers and its members.  This Agreement has been duly and
validly  executed  and  delivered  by the  Sellers and  constitutes  a valid and
binding  obligation of the Sellers  enforceable  against them in accordance with
its terms. The execution,  delivery, and performance of this Agreement, and each
other agreement,  instrument and document  required herein to be executed by the
Sellers does not (a) violate any federal,  state, county, or local law, rule, or
regulation  applicable to the Sellers,  the Sellers' business or the Assets, (b)
violate or conflict with, or permit the  cancellation of, any agreement to which
any of the  Sellers  is a party,  or by which any Seller or its  properties  are
bound,  or result in the creation of any lien,  security  interest,  charge,  or
encumbrance  upon any of such  properties,  (c) permit the  acceleration  of the
maturity of any indebtedness of, or any indebtedness secured by the property of,
Target Center,  or (d) violate or conflict with any provision of the Articles of
Organization  or  Regulations of Target Center.  No action,  consent,  waiver or
approval of, or filing with, any federal,  state,  county or local  governmental
authority is required by any of the Sellers in  connection  with the  execution,
delivery,  or  performance of this Agreement (or any agreement or other document
executed in connection herewith).

3.4 Financial  Statements.  The unaudited  balance sheet and income statement of
Target Center as of and for each of the years ended  December 31, 1998 and 1999,
and the unaudited  balance sheet and income statement of Target Center as of and
for the month ended January 31, 2000 (collectively,  the "Financial Statements")
are attached hereto as Exhibit D. 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 Target Center as of
the  indicated  dates and for the  indicated  periods.  Except as  disclosed  in
Schedule 3.4 and except to the extent  specifically  and fully  reflected in the
Financial  Statements  (including  the  notes  thereto),  Target  Center  has no
liabilities  of a type that would be  required  to be  reflected  as such in the
Financial   Statements   (including   the  notes  thereto)  other  than  current
liabilities  on  open  account  incurred  in the  ordinary  course  of  business
consistent  with past  practices.  Except as set forth in  Schedule  3.4 hereto,
since  January  1,  1999,  there  has been no  material  adverse  change  in the
financial position, assets, results of operations, or business of Target Center.

3.5 Conduct of Business;  Certain  Actions.  Except as set forth on Schedule 3.5
attached hereto, since January 1, 1999, Target Center has conducted its Business
and operations of the Business in the ordinary  course and  consistent  with its
past  practices  and has  not,  with  respect  to or in a manner  affecting  the
Business (a) purchased or retired any indebtedness  from any Seller,  purchased,
retired,  or redeemed any membership interest from any Seller, or engaged in any
other  transaction  that  involves or requires  distributions  of money or other
assets from Target Center to any Seller if such other transaction is not done in
the ordinary  course of business and is not  consistent  with past  practices of
Target Center,  (b) increased the  compensation  of any of the Sellers or of any
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  Target  Center,  (c)  made  capital  expenditures
exceeding $2,000 individually or $5,000 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  $2,000,  (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 Target Center's debts,  rights, or claims against third parties,  (i) amended
its Articles of Organization  or Regulations,  (j) made or paid any severance or
termination  payment to any employee 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 the
Sellers,  its  owners,  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 Target Center'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, Target Center.

3.6  Ownership of Assets;  Licenses,  Permits,  etc.  Target Center has good and
marketable  title to all of the Assets  listed on Schedule 1.3 free and clear of
all liens,  security interests,  claims and encumbrances of any kind whatsoever,
except for those encumbrances specifically set forth on Schedule 3.6. The Assets
include  all  property  and  assets,  real,  personal  and mixed,  tangible  and
intangible,  including  leases and other  contracts,  which are required for, or
used in connection with, the operation of Target Center as currently  conducted.
The Assets 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 adequate for the conduct of Target  Center's  business.  Attached  hereto as
Schedule 3.6 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 Target  Center and used or relied on
(or to be used or relied  on) in  connection  with the  Assets  or the  Business
("Permits").  Target  Center has complied in all material  respects,  and Target
Center is in compliance in all material respects,  with the terms and conditions
of any such Permits.  To the best knowledge of Sellers,  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 of Target  Center.  No
claim has been made by any governmental  authority (and, to the knowledge of the
Sellers,  no such claim has been  threatened)  to the  effect  that a Permit not
possessed by Target Center is necessary in respect of the business  conducted by
Target Center.  All of the Permits noted on the attached Schedule 3.6 are freely
assignable to Prime and Newco.

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,  affecting  the  Assets or the
         Business.

(b)      Target  Center has complied in all material  respects with and obtained
         all  authorizations  and made all filings  required  by all  applicable
         environmental  laws. During Target Center's  operation and ownership of
         the properties occupied or used by Target Center,  such properties,  to
         the best  knowledge  of Sellers,  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 financial position of Target Center.

(c)  Target   Center  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 Target  Center or in which  Target  Center has the sole  right,  license,  or
interest.  Target  Center  is not a party to any  license  agreement,  either as
licensor or licensee, with respect to any patents,  trademarks,  trade names, or
copyrights.  Target Center has not received any notice that it is infringing any
patent,  trademark,  trade name,  or copyright of others.  Target Center and its
affiliates may continue to use any such intellectual  property,  as permitted by
this Agreement,  and any such intellectual  property is irrevocably licensed for
use royalty free by Target Center and its affiliates to Newco.

3.9 Compliance  with Laws.  With respect to the Assets and the Business,  Target
Center has complied in all material respects, and Target Center 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  Target Center to the effect
that the business conducted by Target Center 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 Target  Center 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 Sellers,  no event directly  relating to Target Center 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 Target Center during the past three (3) years,  including
without  limitation  any change  which has  resulted in any period  during which
Target Center had no insurance coverage. Excluding insurance policies which have
expired  and been  replaced,  no  insurance  policy  of Target  Center  has been
canceled  within  the last three (3) years and no threat has been made to cancel
any insurance policy of Target Center within such period.

3.11 Employee  Benefit  Matters.  Except as set forth on Schedule  3.11,  Target
Center 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).  Target  Center  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) that relate to or affect the Assets or the Business,
to which Target  Center is a party or by which Target  Center 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 of
Target Center  (collectively  the "Contracts" and  individually,  a "Contract").
Target  Center is not and,  to the best  knowledge  of  Sellers,  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 Target Center
or, to the best  knowledge  of Sellers,  by any other party  thereto)  under any
Contract.  Target  Center 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 the  Assets or the  consummation  of the  transactions  contemplated
hereby.  Target Center 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 Sellers,  threatened  against  Target Center
that  affect or relate to the Assets or the  Business,  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 Target Center which  (individually  or in the
aggregate) is material, and Target Center has not been, and Target Center 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  Target  Center 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
Target  Center 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 Target Center. 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 Target  Center's  estimated  Tax  liabilities  for the
respective  periods then ended and all prior  periods.  As of the Closing  Date,
Target  Center 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 Target Center between the Effective Time and the Closing Date.
Target  Center 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 Target Center with
respect to any Taxes owed or allegedly owed by Target  Center.  There are no tax
liens on any of the assets of Target  Center.  Proper and accurate  amounts have
been  withheld and remitted by Target  Center 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. Target Center 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 Target
Center who have been  employed in the  operation  of the Business or who utilize
(or are necessary for the utilization of) the Assets (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 Target  Center to any  Employees  from  January 1, 1999
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 Target Center is a party and all  severance  benefits  which
any  director,  Employee or sales  representative  of Target Center is or may be
entitled to receive.  Target Center 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 Target Center is a party
and under which its  employees  are entitled to receive  benefits of any nature.
Sellers  have no  knowledge of any pending or  threatened  (i) labor  dispute or
union  organization  campaign  relating to Target  Center,  (ii) claims  against
Target Center or the Sellers by any employees of Target Center (other than those
certain Workers'  Compensation claims specifically  described on Schedule 3.13),
or (iii)  terminations,  resignations  or retirements of any employees of Target
Center.  None of the  employees of Target  Center are  represented  by any labor
union or  organization.  There is no unfair labor  practice claim against Target
Center before the National Labor Relations  Board or any strike,  labor dispute,
work  slowdown,  or work  stoppage  pending or  threatened  against or involving
Target Center.

3.16  Business  Relations.  The total number of  Refractive  Surgery  procedures
performed at the Target  Center,  the number of  Refractive  Surgery  procedures
performed by each Physician at the Target  Center,  and the number of Refractive
Surgery  procedures  performed by others at the Target Center,  in each case for
calendar years 1998 and 1999, are as set forth on Schedule 3.16. Sellers have no
reason to believe and have not been  notified  that any  supplier or customer of
Target Center will cease or refuse to do business with Target Center or Newco in
the same manner as  previously  conducted  with Target  Center 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 Assets or the
Business. Target Center 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 Target Center.

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 January 31, 2000, arose
from  transactions  occurring in the ordinary course of Target Center'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 Target  Center's  business  since
January 31, 2000 and consistent with past practices of Target Center,  there are
no material  liabilities  of Target  Center  other than those  reflected  in the
Financial  Statements.  Adequate  provision  has  been  made  for  uncollectible
Accounts  Receivable.  Through the Closing Date, Target Center has collected its
Accounts Receivable and has paid or performed all liabilities and obligations of
Target Center in the ordinary course,  consistent with past practices. As of the
Closing Date, the amount of Working Capital (as  hereinafter  defined) of Target
Center  included in the Assets shall not be less than  $25,000.  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.

3.18 Agents. Except as set forth on Schedule 3.18 attached hereto, Target Center
has  not  designated  or  appointed  any  person  (other  than  Target  Center's
employees,  officers  and  directors)  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 Members,  Managers and Employees.  Target Center
does not owe any  indebtedness  to any of the  Sellers  or any of its  officers,
managers or employees or have indebtedness owed to it from any of the Sellers or
any of its officers,  managers or employees,  excluding  indebtedness for travel
advances  or similar  advances  for  expenses  incurred  on behalf of and in the
ordinary course of business of Target Center and consistent with Target Center's
past  practices.  As of the Effective  Time and the Closing Date all amounts due
Target  Center  from any of the Sellers or any  officer,  manager or employee of
Target Center (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,  Target Center does not employ or have any  relationship,  related to or
arising out of the Assets or the  Business,  with any  individual,  corporation,
partnership,  or other entity whose  compensation from Target Center 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 any Sellers from third parties (including,  without limitation,  the
spouses  of  any  Seller)  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.  No Seller has engaged, or caused any liability to be incurred to,
any finder, broker, or sales agent (or has paid, or will 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, no Seller or any affiliate of any Seller,  and to
the knowledge of Sellers no officer, manager or employee of Target Center or any
affiliate  of any  officer,  manager  or  employee  of  Target  Center,  has any
ownership  interest in any competitor,  customer or supplier of Target Center or
any property used in the operation of the business of Target Center.

3.24  Warranties.  Except as set forth on Schedule  3.24,  Target Center has not
made any  warranties or guarantees to third parties with respect to any products
sold or services  rendered by it, other than implied  warranties.  Except as set
forth on  Schedule  3.24  attached  hereto,  no claims  for breach of product or
service warranties have been made against Target Center.

3.25 No  Defaults.  No Seller is aware of any  breach  or  default  by any other
     Seller of any of the representations,  warranties,  covenants or agreements
     contained herein.

3.26     Investment Representations.  Each Seller:
         --------------------------

(a)      Is an "accredited investor," and has not retained or consulted with any
         "purchaser  representative"  (as such terms are  defined in Rule 501 of
         Regulation D promulgated  under the Securities  Act in connection  with
         its  execution  of  this   Agreement  and  the   consummation   of  the
         transactions contemplated hereby;

(b)  Has such knowledge and experience in financial and business matters that it
     is capable of  evaluating  the merits and risks of an  investment by Target
     Center in Newco;

(c)  Will acquire its direct or indirect Newco interests for its own account for
     investment  and not with the view  toward  resale  or  redistribution  in a
     manner which would require registration under the Securities Act, the Texas
     Securities Act, as amended,  or the securities laws of any other state, and
     Sellers do not presently  have any reason to anticipate any change in their
     respective  circumstances or other particular occasion or event which would
     cause  such  Seller to sell its Newco  interests,  or any part  thereof  or
     interest  therein,  and Sellers  have no present  intention of dividing the
     Newco  interests  with others or reselling  or  otherwise  disposing of the
     Newco interests or any part thereof or interest therein either currently or
     after the  passage  of a fixed or  determinable  amount of time or upon the
     occurrence or nonoccurrence of any predetermined event or circumstance;

(d)      In connection  with entering  into this  Agreement and the  Transaction
         Documents to which each Seller is a party, and in making the investment
         decisions  associated  therewith,  Sellers  have  neither  received nor
         relied on any  representations  or warranties from Newco,  Prime, PMSI,
         the   affiliates  of  the   foregoing  or  the   officers,   directors,
         shareholders,   employees,   partners,  members,  agents,  consultants,
         personnel or similarly  related parties of any of the foregoing,  other
         than those representations and warranties contained in this Agreement;

(e)      Is  able to bear  the  economic  risk  of an  investment  in the  Newco
         interests  and it has  sufficient  net  worth to  sustain a loss of its
         entire  investment  without material  economic  hardship if such a loss
         should occur; and

(f)      Acknowledges  that the Newco interests have not been  registered  under
         the Securities  Act, or the securities laws of any of the states of the
         United  States,  that an investment in the Newco  interests  involves a
         high  degree of risk,  and that the  Newco  interests  are an  illiquid
         investment.

ARTICLE IV

                                    Covenants

4.1 Name Change.  For so long as (i) any of the Sellers remain  obligated  under
this Agreement, including, without limitation, obligations arising under Section
8.6, or, (ii) the  Management  Agreement has not been  terminated  (other than a
termination by Newco for cause as described  therein),  Newco may operate within
the  Restricted  Areas (as  hereinafter  defined)  under the name "Mann Berkeley
Caplan Laser Center of Austin," or names similar thereto. At all times,  Sellers
shall own such name and it shall remain their  exclusive  property.  The Sellers
hereby grant to Newco, Prime, and PMSI the irrevocable,  royalty free license to
use such name in connection  with the business of Newco,  in connection with the
business of Prime and PMSI as such  business  relates to the  business of Newco,
and in  connection  with any Retained  Business (as  hereinafter  defined) as to
which the PMSI  Option (as  hereinafter  defined)  is  exercised.  At, or within
thirty (30) days after,  the Closing Date,  the Sellers shall no longer use such
name or any name  deceptively  similar to such name in the Restricted  Areas (as
defined in Section  8.4)(provided,  however, the use of such name or deceptively
similar  name by Newco  shall  not be  deemed a  violation  by  Sellers  of this
covenant).  Sellers and their  affiliates may continue to use the name, or parts
thereof, outside the Restricted Areas.

     4.2  Cooperation  Relating  to  Financial  Statements.   Sellers  agree  to
cooperate with Prime in its  preparation  of any financial  statements of Target
Center and Newco which Prime or its affiliates may be required by any applicable
law to prepare.

4.3 Member and Manager Action. The Sellers each agree to vote their interests in
Target Center, and to take such actions as may be necessary in their capacity as
managers of Target Center,  to authorize and direct Target Center to perform all
of its obligations under this Agreement and under the  Organizational  Documents
and  Transaction  Documents  to which it is a party.  Furthermore,  Sellers each
agree that,  until such time as none of the Sellers owns any ownership  interest
in Newco,  none of them will,  without  obtaining the prior  written  consent of
Prime (and then only as allowed pursuant to the Transfer  Restriction  Agreement
described in Section 4.5 below),  (i) authorize  the issuance of any  additional
membership  interest  in Target  Center to any third  party,  or (ii)  transfer,
assign, or otherwise  dispose of any membership  interest of Target Center owned
or controlled by any of the Sellers.

4.4 Capital Contributions.  The parties agree that no party shall be required to
make any capital contribution to Newco following the Closing, including, without
limitation, for purposes of providing working capital;  provided,  however, that
this  sentence  shall not affect any party's  obligations  under Article VI with
respect to any breach of the  representations  or warranties  made by that party
under this Agreement.

4.5  Ownership  Interest  Transfer  Restriction  Agreement.  Each of the Sellers
agrees  that  it,  and its  spouse(if  any),  will  execute,  on or prior to the
Closing,   the  Membership   Interest   Transfer   Restriction   Agreement,   in
substantially  the form attached hereto as Exhibit E (the "Transfer  Restriction
Agreement"),  that  imposes  certain  limitations  and  conditions  on the sale,
transfer,  assignment or other  disposition  of any interest that is directly or
indirectly   owned  or  controlled  by  such  party  in  Target  Center  or  the
subsidiaries or affiliates of Target Center.

4.6  Insurance.  Newco agrees to maintain,  for five (5) years after the Closing
Date, a prior acts insurance policy providing  insurance  coverage for Newco and
for Refractive  Surgery  procedures  performed  prior to the Closing Date at the
Austin,  Texas  facility of Target  Center,  of the same  scope,  in the same or
greater  amounts  and subject to the same or smaller  deductibles  as the Target
Center's insurance in effect immediately prior to the Closing Date.

     4.7 Management Agreement.  Newco and MBEC shall execute, on or prior to the
Closing,  the Management  Agreement,  in substantially the same form as attached
hereto as Exhibit F (the "Management Agreement").

         4.8 Other  Parties.  Without  the express  written  consent of Sellers,
Prime (through its control of Newco) will not allow LASIK  Investors,  L.L.C., a
Delaware  limited  liability  company  ("LASIK")  or Barnet  Dulaney Eye Center,
P.L.L.C.,  an Arizona professional limited liability company ("BDEC"), or any of
the current (as of the  Effective  Date) or any former owners of either LASIK or
BDEC to become involved in or exercise any control or influence over Newco,  nor
will Prime sell,  convey or  otherwise  transfer,  all, or any  portion,  of its
ownership  interest in Newco to LASIK,  BDEC, or any current or former owners of
either LASIK or BDEC. If LASIK or BDEC, or any of their  affiliates,  merge with
Prime in a  merger  wherein  Prime is not the  surviving  entity,  or  otherwise
acquire  greater than fifty  percent  (50%) of the voting  equity  securities of
Prime,  Sellers and Target Center shall have the right (but not the  obligation)
to  terminate  this  Agreement,  and  MBEC  shall  have the  right  (but not the
obligation) to terminate the Management Agreement,  within six (6) months of the
effective  date of such merger or  acquisition  of control by giving thirty (30)
days prior written notice to Prime (or Prime's  successor) of such  termination.
Nothing  herein shall be construed as to prohibit or restrict any current (as of
the Effective  Date) or former  physician owner of LASIK or BDEC from serving on
the Board of Directors of PMSI, and fully participating as a board member.

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 each Seller to Close):

(a)      pay the Purchase Price to Target Center;

(b)      ensure that the Warrants are delivered to Target Center;

(c)      ensure  that  the  Incidental   Registration   Rights   Agreement,   in
         substantially  the same  form as  attached  hereto  as  Exhibit  G (the
         "Rights Agreement"), is executed and delivered to Target Center;

(d)  execute  and  deliver  the  Assignment  and  Assumption  Agreement  and the
     Organizational Documents to which it is a party; and

(e)      deliver such good  standing  certificates,  officer  certificates,  and
         similar  documents  and  certificates  as counsel for Target Center may
         reasonably require.

     5.2 Sellers Closing Obligations. At the Closing, each Seller shall (each of
which is a condition to the obligations of Prime to Close):

(a)  execute and deliver each Transaction Document required to be executed by it
     pursuant to this Agreement;

(b)      cause MBEC to execute and deliver the Management Agreement; and

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

5.3 Newco's Closing Obligations. At the Closing, Newco shall execute and deliver
the Assignment and Assumption Agreement,  the Management Agreement and such good
standing   certificates,   officer  certificates,   and  similar  documents  and
certificates as counsel for Prime or any of the Sellers may reasonably require.

ARTICLE VI

                       Indemnification of Prime and Newco

6.1  Indemnification  of Prime and Newco. The Sellers and MBEC, each jointly and
severally,  agree to indemnify and hold harmless Prime,  each subsidiary  and/or
affiliate of Prime (including,  without  limitation,  PMSI), and,  following the
Closing,  Newco,  and each  officer,  director,  and  employee of Prime and each
subsidiary  and affiliate of Prime,  and  affiliate of Prime and,  following the
Closing, Newco (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 (a) any breach or default by any Seller of
any of the  representations,  warranties,  covenants or agreements  contained in
this Agreement or any Transaction Document (including,  without limitation,  the
Organizational  Documents and the Management  Agreement),  (b) any obligation or
liability of Target Center not assumed by Newco  pursuant to the  Assignment and
Assumption Agreement,  or (c) any obligations or liabilities with respect to any
claims  arising out of actions or omissions  by any Seller prior to Closing,  or
actions or  omissions  by any Seller  after  Closing that are not related to the
business or management of Newco,  or actions or omissions by any Seller that are
a breach of a fiduciary  duty. With respect to  indemnification  for Indemnified
Costs  arising  solely  out of the  breach,  default,  action or  omission  of a
Physician  or  Micheletti,   the  Prime  Indemnified   Parties  shall  not  seek
indemnification  under this Section from any Physician or Micheletti who did not
cause, allow or contribute to such breach, default, action or omission that gave
rise to the Indemnified Costs;  provided,  however,  in all such cases the Prime
Indemnified  Parties will be able to seek  indemnity  jointly and severally from
MBEC and Target Center, in addition to the Physician or Micheletti whose breach,
default,  action  or  omission  gave  rise  to the  Indemnified  Costs.  For all
indemnity  obligations  arising pursuant to this Section,  the Prime Indemnified
Parties will demand payment first from MBEC and Target  Center,  but if MBEC and
Target Center fail or refuse to pay such  indemnity  obligation,  then the Prime
Indemnified Parties may seek indemnity from the Physicians or Micheletti, as any
of them may be liable under the provisions of this Section.

6.2 Defense of Third-Party  Claims. A Prime  Indemnified Party shall give prompt
written  notice to Sellers of the  commencement  or assertion of any third party
action  in  respect  of  which  such   Prime   Indemnified   Party   shall  seek
indemnification  hereunder.  Any failure so to notify  Sellers shall not relieve
Sellers from any liability  that they may have to such Prime  Indemnified  Party
under  this  ARTICLE  unless  the  failure to give such  notice  materially  and
adversely prejudices Sellers.  Sellers 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)      Sellers  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)      Sellers  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)      Sellers  shall not be  entitled  to control  (but shall be  entitled to
         participate  at their 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  Sellers  fail 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
         Sellers or Target Center, without the prior written consent of Sellers.

(e)      Sellers 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  Sellers  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 Security.  Without limiting or adversely affecting the rights of Prime under
Section 8.11, and in order to secure full and prompt payment of the  obligations
of each of the Sellers under this ARTICLE,  Target Center hereby grants to Prime
a continuing  security  interest in and to  distributions  it may be entitled to
receive at any time after the Closing in respect of any ownership  interest held
by it in Newco. In connection with the grant of a security interest contained in
this  Section,  each  Seller  agrees (i) to execute all  documents,  agreements,
instruments and certificates,  and to take such other actions,  as are necessary
in order to cause Target  Center to fully  evidence  and perfect  such  security
interest,  and (ii) that it, for a period of five (5) years  after the  Closing,
will not,  without  obtaining the express prior written consent of Prime in each
instance,  grant or assign to any  person or entity  rights of any nature in the
distributions  covered  by  the  security  interest  granted  in  this  Section,
irrespective  of  whether  such  rights are to be senior or  subordinate  to the
rights granted under this Section.

ARTICLE VII

                           Indemnification of Sellers

7.1  Indemnification  of Sellers.  Prime agrees to indemnify  and hold  harmless
Sellers and Newco  (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 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 (including,  without limitation,  the Organizational
Documents).

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

                             Post Closing Agreements

8.1 Transition of Business. Each Seller agrees to cooperate fully with Prime and
Newco in  transitioning  the  business  conducted,  and  business  relationships
maintained  by, Target Center prior to the Closing,  to Newco after the Closing;
and each  Seller  agrees not to take any action or make any  disclosure  which a
reasonable  person would expect to  adversely  alter or impair any  relationship
with any  customer,  or other  service  recipient,  person or  entity  which did
business with Target Center prior to the Closing. Each Seller agrees to promptly
remit to Newco any payments received by Target Center or any Seller for services
provided  by  Target  Center  after  the  Effective  Time or by Newco  after the
Closing.  Furthermore,  Sellers  agree to  deposit  any such  payments  received
directly to a deposit account designated and controlled by Newco or to take such
other action as may be requested by Prime to implement and maintain a system for
remitting payments due Newco which come into the possession or control of Target
Center or any Seller.

8.2 Ratification by Newco.  Prime and Target Center agree that by executing this
Agreement  they are deemed to be voting  their  ownership  interests in Newco to
authorize  Newco  to enter  into  and  perform  this  Agreement  and each of the
Transaction  Documents to which it is a party.  Prime and Target Center agree to
execute such resolutions and written consents,  and take such other actions,  in
their  capacities  as members of Newco,  as any party shall  reasonably  require
after the Closing to have Newco ratify and adopt this Agreement, notwithstanding
the official date of Newco's creation.

8.3  Confidentiality  Agreement.  Each  Seller  acknowledges  that  through  its
relationship  with  Newco,  it will be exposed to  Proprietary  Information  (as
defined  below) of Newco  and/or  each of Newco's  present or future  affiliates
(which includes,  without  limitation,  Prime, PMSI and each of their present or
future affiliates, but excludes, for purposes of this Section, each Seller) (the
party owning such  Proprietary  Information is referred to as the  "Discloser"),
that such Proprietary Information is unique and valuable and that such Discloser
would suffer irreparable injury if its Proprietary  Information were divulged to
those in competition  with  Discloser.  "Proprietary  Information"  shall be all
information  concerning  Discloser  which a party  acquires,  or to which it has
access  through  its  relationship  with  Discloser  or Newco  that has not been
publicly  disclosed  by  Discloser  or that is not a matter of common  knowledge
among  Discloser's  competitors,  including,  but not  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,  each Seller agrees
that it will not, at any time after the  Closing:  (i)  directly or  indirectly,
disclose any Proprietary Information to any person except its owners, directors,
managers,  officers,  employees,  agents and  consultants  who need to know such
Proprietary  Information in connection with such party's relationship with Newco
nor (ii) use  Proprietary  Information  in any way,  except for the  purposes of
Newco.

         Within   forty-eight   (48)  hours  of  termination  of  its  ownership
(directly,   or  indirectly   through  Target  Center)  interest  in  Newco,  as
applicable,  whether  voluntary or involuntary,  each Seller will deliver to the
appropriate Discloser (without retaining copies thereof) all documents,  records
or other  memorializations  including copies of documents and any notes which it
has  prepared  that  contain   Proprietary   Information,   all  other  tangible
Proprietary  Information  in its  possession  or control and all of  Discloser's
credit cards, keys, equipment,  vehicles,  supplies and other materials that are
in its possession or under its control.

         Notwithstanding  any other provision of this Section, to the extent any
Proprietary  Information is owned  exclusively by Newco,  Newco hereby grants an
irrevocable,  royalty  free  license to Prime,  PMSI,  each of Prime's or PMSI's
present  or future  affiliates,  and each  Seller  and their  present  or future
affiliates, to use and disseminate such Proprietary Information.

8.4 Seller Non-Competition Agreement. As a material inducement to Prime to enter
into this  Agreement,  each Seller hereby agrees that,  until the earlier of the
termination of the Management  Agreement  (other than a termination by Newco for
cause as  described  therein)  or five (5) years after the  Closing  Date,  each
Seller will not  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 one percent (1%) of any class of outstanding securities), or as a
principal,  shareholder, agent, employer, 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 Newco and Prime,  commit any of the  following  acts,
which acts shall be considered violations of this covenant not to compete:

(a)      Directly or indirectly,  within the "Restricted  Areas" (as hereinafter
         defined)  engage  in, or  provide  any  services  related  to,  (i) the
         operating  of  Refractive   Surgery  centers,   (ii)  the  manufacture,
         maintenance,  refurbishing,  repair,  sale, or leasing of any equipment
         related  to or  necessary  for  the  operating  of  Refractive  Surgery
         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 provide  Refractive Surgery services,  including
         without  limitation,  Refractive  Surgery patient services,  Refractive
         Surgery management services,  Refractive Surgery marketing services, or
         similar services, anywhere within the Restricted Areas.

(c)      Directly or indirectly request or advise any person,  firm,  physician,
         corporation or other entity having a business  relationship with Newco,
         Prime or any  affiliate  or  related  entity  of  either  of  them,  to
         withdraw,  curtail,  or cancel its business  with Newco,  Prime or such
         affiliate or related entity, including,  without limitation,  marketing
         efforts and  activities  outside the  Restricted  Areas whose  targeted
         audience  includes (in whole or in part) any  potential  any  potential
         Refractive Surgery customers inside the Restricted Areas; or

(d)      Directly  or  indirectly  hire  any  employee  of  Newco,  Prime or any
         affiliate or related  entity of either of them, or induce or attempt to
         influence any employee of Newco, Prime or any such affiliate or related
         entity to terminate his or her employment with Newco, Prime or any such
         affiliate or related entity. No employees, contract physicians or staff
         of MBEC shall be considered to be working for an "affiliate" of Newco.

         For purposes hereof,  the "Restricted  Areas" are anywhere within forty
(40) miles of (i)  Target  Center's  location  at 2600 Via  Fortuna,  Suite 400,
Austin,  Texas 78746. The covenants in this Section 8.4 shall terminate if Newco
terminates the Management Agreement (other than a termination by Newco for cause
as described therein).

8.5 Prime Non-Competition Agreement. As a material inducement to Seller to enter
into this  Agreement,  Prime hereby agrees that,  until five (5) years after the
Closing  Date,  neither  Prime  nor  any  of its  affiliates  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 one percent
(1%) of any class of outstanding  securities),  or as a principal,  shareholder,
agent,  employer,  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 Newco and Seller,  directly or indirectly hire any employee of Newco,
Seller or any  affiliate  or  related  entity  of  either of them,  or induce or
attempt to  influence  any  employee of Newco,  Seller or any such  affiliate or
related entity to terminate his or her employment with Newco, Seller or any such
affiliate or related entity.

8.6 Exclusive Use. Except as expressly otherwise provided below, during the term
of this Agreement,  each Physician hereby agrees that, without the prior written
consent of both Newco and Prime,  each Physician  will perform,  and will direct
all  other  medically  trained  or  licensed  medical  professionals  under  the
direction or control of Physician to perform, all services related to Refractive
Surgery for patients residing or domiciled within the Austin, Texas metropolitan
area only at the facilities of, and using the equipment of, Newco.

         Mann and Caplan each  agree,  until the  expiration  of the fifth (5th)
anniversary  of the  Closing  Date,  to manage and  operate  Newco,  and perform
Refractive Surgery, in a manner consistent with the management and operation of,
and their  respective  performance  of  Refractive  Surgery at, Target Center in
1999.  Berkeley agrees,  until the expiration of the second (2nd) anniversary of
the Closing Date, to manage and operate Newco, and perform  Refractive  Surgery,
in a manner consistent with the management and operation of, and his performance
of Refractive  Surgery at, Target Center in 1999. Each Physician agrees,  for so
long as he remains  obligated under the immediately  preceding two (2) sentences
of this paragraph, to perform Refractive Surgery, or cause Refractive Surgery to
be  performed  by a  physician  employed  by or  affiliated  with  MBEC,  at the
facilities  of Newco on at least  forty-two  (42) separate days in the aggregate
during  each  calendar  year,  including a minimum of three (3) days each month,
subject to patient  volume.  Each  Physician  agrees,  for so long as he remains
obligated  under this  paragraph of Section 8.6, to devote  sufficient  business
time  and  attention,  and to use his  best  efforts,  to  create  and  maintain
sufficient patient volume to satisfy his obligations under this Section 8.6.

         For so  long as the  Management  Agreement  is in  effect,  MBEC  shall
compensate  the  Physicians  for all  procedures  performed at the facilities of
Newco pursuant to this Agreement.

         The  obligations  under this Section shall not apply to any  Refractive
Surgery to be paid for, or reimbursed by, Medicare,  Medicaid,  Champus,  or any
other state or federal  health care program,  or in any other instance where the
operation of this Agreement would constitute a violation of applicable law.

8.7 Right of First Refusal.  Each Seller and MBEC represent and warrant to Prime
and PMSI that as of the Effective Time it does not operate,  manage, or have any
direct or indirect  ownership  interest in, any entity that owns,  operates,  or
manages any Refractive  Surgery center (currently  existing or proposed),  other
than as set forth on Schedule 8.7 which,  together with any  Refractive  Surgery
center,  business or operation developed or acquired after the Effective Time as
permitted under the terms of this Agreement,  shall be referred to herein as the
"Retained  Businesses."  Sellers and MBEC shall give Prime prompt written notice
of establishing  or acquiring any Refractive  Surgery center after the Effective
Time for so long as the Management  Agreement,  or any extension thereof,  is in
force (this  obligation will not terminate,  however,  upon a termination of the
Management Agreement,  or any extension thereof, by Newco for cause as described
therein,  but shall  continue to the  benefit of Prime).  Sellers and MBEC agree
that  PMSI is  hereby  granted  a right of first  refusal  (the  "PMSI  Option")
pursuant to which PMSI or one of its direct or indirect subsidiaries may, in its
sole  discretion and for so long as the Management  Agreement,  or any extension
thereof,  is in force  (the PMSI  Option  will not  terminate,  however,  upon a
termination of the Management Agreement,  or any extension thereof, by Newco for
cause as  described  therein,  but shall  continue to the benefit of PMSI),  and
without any  obligation to do so,  acquire from  Sellers,  MBEC, or the Retained
Businesses, as the case may be, at the price offered by (and upon the same terms
applicable  to)  any  third  party  offer,  all or a  portion  of the  ownership
interest,  business or assets of a Retained  Business then held by Sellers,  the
Retained Business or MBEC, prior to any sale,  conveyance,  encumbrance or other
transfer of the Retained Business, or any assets thereof or interest therein, in
whole or in part, to any third party (including  without limitation any interest
dilution that occurs due to the issuance of any new ownership or other interests
in a Retained Business). The foregoing right of first refusal shall not apply to
any sale or  transfer  of a minority  ownership  interest  to a  physician  or a
current full time  employee of MBEC,  provided that no such  permitted  transfer
shall be allowed if it results  in the  Sellers,  or any of them,  owning in the
aggregate  less  than 51% of the  outstanding  ownership  interests  (both as to
voting rights and rights to income and  distributions)  of the Retained Business
in question.  If the Sellers, or any of them, own in the aggregate less than 51%
of the outstanding  ownership  interests (both as to voting rights and rights to
income and distributions) of a particular  Retained Business,  then no transfers
shall be permitted that are subject to PMSI's right of first refusal.

          All parties hereto  acknowledge and agree that it would be impractical
to exercise an option to purchase  arising pursuant to this Section 8.7 whenever
the proposed  consideration  to be received by the Sellers or MBEC is other than
cash, cash  equivalents or stock of publicly traded  companies.  Therefore,  the
parties agree that no transfer shall be permitted  whenever the consideration to
be received from the proposed transferee is other than cash, cash equivalents or
stock of publicly traded  companies.  Upon receiving any such third party offer,
Sellers or MBEC shall give prompt written notice thereof to PMSI.  Following its
receipt of such  notice,  PMSI shall have thirty (30) days to exercise  the PMSI
Option, and Sellers and MBEC agree that Sellers and MBEC may not take any action
with  respect to the third party offer  until PMSI has either  provided  written
notice of its intent not to  exercise  the PMSI  Option,  or the thirty (30) day
period has expired without any election by PMSI to exercise the PMSI Option. The
closing of any  purchase  and sale  pursuant  to an  exercise of the PMSI Option
shall occur within 30 business days following  such  exercise,  and the purchase
price shall be paid in identical form as shall have been set forth in the notice
of third party  offer.  In  connection  with any  exercise of the PMSI Option by
PMSI, Sellers and MBEC shall deliver all agreements,  documents, instruments and
certificates,  and take such other  action,  as may be  reasonably  necessary in
order to consummate the purchase and sale contemplated in this Section, and PMSI
or its designated purchasing subsidiary shall receive the acquired interest free
and clear of any  liens,  claims or  encumbrances.  The  parties  agree that any
acquisition  pursuant  to  exercise  of the PMSI  Option  shall be  accomplished
through an asset purchase, unless the parties otherwise agree.

8.8 Compliance with Applicable Law. In accordance with Texas Business & Commerce
Code Section 15.50 (the "Applicable Statutory Provision"), this Agreement hereby
provides for the following:

(a)  each  Physician  shall  not  hereby  be  denied  access  to any list of his
     patients whom he has seen or treated;

(b)      each Physician  shall not hereby be denied access to medical records of
         his patients upon authorization of the patient,  and any copies of such
         medical  records  obtained  or  possessed  by Prime  or Newco  shall be
         provided to the Physician for a reasonable  fee as  established  by the
         Texas State Board of Medical  Examiners under Section 5.08(o),  Medical
         Practice Act (Article 4495b, Vernon's Texas Civil Statutes);

(c)      access to any such list of  patients or to any such  patients'  medical
         records referred to in (a) or (b) above, shall not require such list or
         records to be  provided in a format  different  than that by which such
         records are  maintained,  except by the mutual consent of Newco and the
         applicable Physician;

(d)      each  Physician  shall  be  entitled  to buy  out  his  performance  of
         obligations  arising under Section 8.6 of this Agreement (but only such
         obligations  as is necessary in order for this Agreement to comply with
         the Applicable Statutory Provision) for One Half of the Purchase Price,
         less any  amounts  paid  pursuant  to Section  8.10  hereof;  provided,
         however, that in order for such buy out to be effective,  the Physician
         must  also  convey  his  entire  equity  interest  in Newco  to  Prime,
         unencumbered; and

(e)      the Physician shall not hereby be prohibited from providing  continuing
         care and treatment to a specific  patient or patients during the course
         of an acute illness.

         Each Physician agrees that the buy out amount set forth in this Section
8.8 is a reasonable price and represents a fair value for his performance of his
obligations  hereunder.  Physicians  and Prime have each elected to utilize such
reasonable  price in lieu of arbitration  pursuant to the  Applicable  Statutory
Provision.

8.9 Agreement.  Each Seller has reviewed and carefully considered the provisions
of Sections  8.3,  8.4,  8.6, 8.7 and 8.8 and,  having done so,  agrees that the
restrictions  applicable to it as set forth therein (a) are fair and  reasonable
with respect to time,  geographic area and scope, (b) are not unduly  burdensome
to them, and (c) are reasonably  required for the protection of the interests of
the other parties hereto for whose benefit such restrictions were agreed upon.

8.10 Remedies. Each Seller agrees that a violation on its part of any applicable
covenant contained in Sections 8.3, 8.4, 8.6 or 8.7 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
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  liquidated
damages pursuant to this Section and any other additional damages.

         Without limiting the indemnity provisions of Articles VI or VII of this
Agreement,  the  parties  hereto  agree  that in the event a claim  for  damages
resulting from a breach of warranty or failure of a representation under Article
II or Article III of this  Agreement is made against a party to this  Agreement,
the  party  alleged  to have  breached  this  Agreement  shall be  provided,  if
possible,  with a reasonable  opportunity to cure any breach of a warranty under
this  Agreement.  No remedy shall be afforded to any party to this Agreement for
any failure of a  representation  or  warranty  under this  Article  that is not
material (as defined in Section 9.9).

8.11 Right of Offset.  Each Seller agrees that Newco shall have rights of offset
against  distributions to each Seller in respect of any ownership  interest such
Seller  may have in Newco at any time  following  the  Closing,  for any and all
debts,  obligations or  liabilities  that such Seller may have to Prime or PMSI,
including,  without limitation, any liability arising out of or relating to such
Seller's indemnity obligations under this Agreement or any Transaction Document.
Each Seller  hereby  authorizes  and directs  Newco,  and appoints  Newco as its
attorney in fact,  to withhold and pay such offset  amounts to Prime and to take
all  other  actions  necessary  to make such  payment.  Newco  hereby  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         8.12 Termination.  This Agreement,  including,  but not limited to, the
obligations contained in this Article VIII (but excluding Article VI and Article
VII),  shall terminate upon the termination of the Management  Agreement  (other
than a termination by Newco for cause as described therein); provided that in no
event shall the provisions of Article VI and Article VII terminate.

ARTICLE IX

                                  Miscellaneous

9.1 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.

9.2  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 fifty percent (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.

9.3  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.  The costs and expenses  incurred by Prime associated  specifically
with the formation and documentation of Newco, including legal fees and expenses
for drafting the Organizational Documents,  shall be paid or reimbursed to Prime
by Newco, but not to exceed $2,000 in any event.

9.4  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 and enforced 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.

9.5  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.

9.6 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:                                 Prime RVC, Inc.
                                       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

Sellers:                               Mann Berkeley Eye Center
with a copy to:                        Donald R. Looper
                                       Looper, Reed, Mark & McGraw
                                       1300 Post Oak Blvd.
                                       Suite 2000
                                       Houston, Texas 77056

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

9.7 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.

9.8 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.

9.9 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  $5,000 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,  Joe
Jenkins,  Cheryl Williams and John Hedrick and (ii) Target Center, it shall mean
such items as are within the actual  knowledge  of any Seller or any  managerial
employee of Target Center who becomes an employee of Newco after the Closing.

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

9.11 Arbitration.  Any controversy  between the parties regarding this Agreement
and any claims arising out of this Agreement or its breach shall be submitted to
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.

9.12 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.

9.13 Post Effective Time  Adjustments.  The parties  acknowledge  and agree that
Target Center has, prior to the Closing Date,  been receiving  revenues,  making
disbursements and incurring payables and receivables  pursuant to the operations
of Target Center in the ordinary course,  including  without  limitation  paying
payroll,  payroll taxes,  trade vendors and other  expenses.  Target Center will
promptly  account  for all such  activity  and the  parties  agree that Newco or
Target Center,  as applicable,  will reimburse the other for any net amounts due
with respect to such post Effective Time activity.

<PAGE>

S-1

                                SIGNATURE PAGE TO

                             CONTRIBUTION AGREEMENT

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

PRIME:                                           PRIME RVC, INC.

                                      By: __________________________________
                                      Printed Name:  _________________________
                                      Title:   ________________________________

NEWCO:                                           PRIME MBC, L.L.C.

                                      By: __________________________________
                                      Printed Name:  _________________________
                                      Title:   ________________________________

TARGET CENTER:                                   MBC HOLDING COMPANY, L.L.C.

                                      By: __________________________________
                                      Printed Name:  _________________________
                                      Title:   ________________________________

                                        ======================================
                                        ======================================

MBEC:                                        MANN BERKELEY EYE CENTER, P.A.

                                      By: __________________________________
                                      Printed Name:  _________________________
                                      Title:   ________________________________

<PAGE>

                                TABLE OF EXHIBITS

Exhibit A         Form of Warrant

Exhibit B         Limited Liability Company Organizational Documents of Newco

Exhibit C         Form of Assignment and Assumption Agreement

Exhibit D         Financial Statements of Target Center

Exhibit E         Form of Transfer Restriction Agreement

Exhibit F         Form of Management Agreement

Exhibit G         Form of Incidental Registration Rights AgreementMEMBERSHIP INTEREST

                         TRANSFER RESTRICTION AGREEMENT

     This Membership Interest Transfer Restriction  Agreement (this "Agreement")
is entered  into  effective as of the 1st day of March,  2000,  by and among MBC
Holding  Company,  L.L.C.,  a Texas limited  liability  company (the "Company"),
Prime RVC,  Inc., a Delaware  corporation  ("Prime"),  Paul Michael  Mann,  M.D.
("Mann"),  Ralph  G.  Berkeley,  M.D.  ("Berkeley"),  Michael  B.  Caplan,  M.D.
("Caplan"),  and Mark F. Micheletti  ("Micheletti").  Mann, Berkeley, Caplan and
Micheletti,  together with any  subsequent  Members in the Company who hereafter
execute this Agreement, are collectively referred to herein as the "Members".

                                R E C I T A L S:

             WHEREAS,  Mann, Berkeley,  Caplan and Micheletti own all the issued
and  outstanding  membership  interests  of the  Company  (all  such  membership
interests,  together with any hereafter acquired, are hereinafter referred to as
the "Membership Interests"); and

             WHEREAS, this Agreement is a "Transaction  Document," as defined in
that  certain  Contribution  Agreement  (the  "Contribution   Agreement")  dated
effective March 1, 2000, by and among Prime,  Prime MBC, L.L.C., a Texas limited
liability  company,  the  Company,  Mann  Berkeley  Eye  Center,  P.A.,  a Texas
professional association, Mann, Berkeley, Caplan and Micheletti.

             WHEREAS,  the  Members,  the Company and Prime desire to enter into
this Agreement to control the distribution of ownership interests in the Company
and to promote the harmonious management of the Company's affairs.

             NOW,  THEREFORE,  in  consideration  of the  foregoing,  the mutual
covenants and agreements contained herein, and for other valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

                                    ARTICLE I

               PERMITTED TRANSFERS; RESTRICTIONS AGAINST TRANSFER

As used in this Agreement,  "Permitted Transfers" shall mean any transfer of all
or any  part of any  Member's  Membership  Interest  to (i) the  members  of the
immediate  family of the Member or a trust or trusts for the  benefit of members
of the immediate family of the Member, provided that after any such transfer the
Member  retains  the sole  express  right to vote,  or direct  the votes of, the
Membership  Interest,  (ii) any other  Member,  provided that after any transfer
pursuant to this subsection (ii) is consummated,  Mann,  Berkeley and Caplan (or
trusts  that  hold  Membership  Interests  as a result  of  Permitted  Transfers
subsection (i) above) must  collectively own in the aggregate at least fifty-one
percent (51%) of the total outstanding  Membership  Interests of the Company, or
(iii) Prime. Any Member transferring all or a portion of its Membership Interest
pursuant to a Permitted  Transfer  shall give  written  notice of the  Permitted
Transfer  (containing the same  information as required for notice under Section
2.1.1) to Prime and the other  Members  fifteen (15) days prior to the effective
date of the Permitted Transfer. Except for a Permitted Transfer, or as otherwise
provided  in this  Agreement,  a Member  shall  not  transfer,  assign,  pledge,
hypothecate,  or in any way alienate any  Membership  Interest,  or any interest
therein,  whether  voluntarily  or by operation of law, or by gift or otherwise,
without the prior written  consent of the Company,  the other Members and Prime,
which  consent  may be  withheld  in their  sole and  absolute  discretion.  Any
purported transfer in violation of any provision of this Agreement shall be void
and  ineffectual,  shall not  operate to transfer  any  interest or title to the
purported  transferee,  and shall give the Company,  the other Members and Prime
options to purchase such Membership Interest in the manner and on the conditions
hereinafter provided. As used in this Agreement, "Option Members" shall mean all
Members of the Company except the Member who, prior to the proposed  transfer or
the  incident  resulting  in the  proposed  transfer  of all or a  portion  of a
Membership Interest, owned such interest.

                                   ARTICLE II

                                     OPTIONS

2.1      OPTION UPON VOLUNTARY TRANSFER.

             2.1.1Notice  of  Intention  to  Transfer.  If a Member  intends  to
voluntarily  transfer any of its Membership  Interest,  other than pursuant to a
Permitted  Transfer,  to any person other than the Company,  and does not obtain
the written consents required in ARTICLE I hereof, the Member shall give written
notice to the other  Members and Prime  stating (i) the  intention to transfer a
Membership  Interest,  (ii) the amount of Membership Interest 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.

             2.1.2Option  to Purchase.  The Option  Members shall have,  and may
exercise  within 30 days after  receipt of the notice of intent to transfer,  an
option  to  purchase  all  or  any  portion  of  the  Membership   Interest  the
transferring Member intends to transfer,  for the price and upon the other terms
stated in the notice of intent to transfer.  If the Option Members fail,  within
such 30-day period,  to exercise  their purchase  option (by delivery of written
notice) with respect to the entire Membership  Interest being  transferred,  the
Option  Members shall be deemed to have elected not to exercise  their  purchase
option with respect to such unpurchased Membership Interest.  Upon any notice of
non-exercise (or deemed  non-exercise) by the Option Members,  Prime shall have,
and may exercise  within 30 days of receipt of notice of such  non-exercise  (or
deemed  non-exercise),  an option to purchase all of such  remaining  Membership
Interest upon the same terms and conditions.

             2.1.3Death  Before Closing.  If a Member who proposed to transfer a
Membership  Interest  dies  prior  to the  closing  of  the  sale  and  purchase
contemplated  by this  Section  2.1, the  Membership  Interest of such  deceased
Member shall be the subject of sale and purchase under Section 2.3.

             2.1.4Allowable  Consideration.  All parties hereto  acknowledge and
agree that it would be  impractical  to exercise  an option to purchase  arising
pursuant to this Section 2.1 whenever the proposed  consideration to be received
by the transferring  Member is other than cash or cash  equivalents.  Therefore,
the parties agree that no transfer  shall be permitted and no option shall arise
pursuant to this Section 2.1 whenever the  consideration to be received from the
proposed transferee is other than cash or cash equivalents.

2.2      OPTION UPON CERTAIN INVOLUNTARY TRANSFERS.

             2  2.1Exercise  Event and  Notice.  The  filing of a  voluntary  or
involuntary petition of bankruptcy by or on behalf of a Member, an assignment by
a Member of any of its Membership Interest, or of any right or interest therein,
for the benefit of creditors, or the voluntary transfer,  transfer by law or any
other transfer,  of any Membership Interest, or of any right or interest therein
(other  than  transfers  governed by ARTICLE I or  Sections  2.1,  2.3 or 2.4 or
ARTICLE  VII  hereof),  shall  give the other  Members  and Prime the  option to
purchase the  Membership  Interest of such bankrupt  Member or such  transferred
Membership  Interest  as  provided  herein.  Upon the filing of a  voluntary  or
involuntary  petition of bankruptcy by or on behalf of a Member or an assignment
by  Member  of any of its  Membership  Interest,  or of any  right  or  interest
therein, for the benefit of creditors, the Member or its personal representative
shall promptly give written  notice of such  occurrence to the other Members and
Prime. In the event of a transfer of Membership  Interest,  as described  above,
the Member  transferring  such  Membership  Interest shall promptly give written
notice of such transfer to the other Members and Prime.

             2.2.2Option  to Purchase.  The Option  Members shall have,  and may
exercise  within 30 days after receipt of the notice of the applicable  exercise
event,  an option to purchase all or any portion of the Membership  Interest the
bankrupt or transferring Member intends to transfer,  for the price and upon the
other terms hereinafter provided. If the Option Members fail, within such 30-day
period,  to exercise their purchase  option (by delivery of written notice) with
respect to the entire Membership Interest being transferred,  the Option Members
shall be deemed to have  elected  not to  exercise  their  purchase  option with
respect to such unpurchased Membership Interest. Upon any notice of non-exercise
(or deemed  non-exercise)  by the Option  Members,  Prime  shall  have,  and may
exercise  within 30 days of  receipt of notice of such  non-exercise  (or deemed
non-exercise),  an option to purchase all of such remaining  Membership Interest
for the price and upon the other terms hereinafter provided.

2.3      PURCHASE AND SALE OF MEMBERSHIP INTEREST UPON DEATH.

             2.3.1Notice   of  Death.   Upon  the  death  of  the  Member,   the
representative  of the estate of the deceased Member shall promptly give written
notice of the death to the other Members and Prime.

             2.3.2Option  to Purchase.  The Option  Members shall have,  and may
exercise  within 30 days  after  receipt  of the  notice of death,  an option to
purchase all or any portion of the Membership  Interest of the deceased  Member,
for the price and upon the  other  terms  hereinafter  provided.  If the  Option
Members fail,  within such 30-day period,  to exercise their purchase option (by
delivery of written  notice)  with  respect to the  entirety of such  Membership
Interest,  the Option  Members  shall be deemed to have  elected not to exercise
their purchase option with respect to such unpurchased Membership Interest. Upon
any notice of non-exercise (or deemed non-exercise) by the Option Members, Prime
shall  have,  and may  exercise  within  30 days of  receipt  of  notice of such
non-exercise  (or  deemed  non-exercise),  an  option  to  purchase  all of such
remaining Membership Interest for the price and upon the other terms hereinafter
provided.

2.4  OPTION UPON DEATH OF A MEMBER'S SPOUSE, TERMINATION OF MARITAL RELATIONSHIP
     OR PARTITION OF COMMUNITY PROPERTY.

             2.4.1Death of Member's Spouse. Each Member and each Member's spouse
agree that in the event the spouse of a Member  predeceases such Member and such
Member does not succeed by the spouse's  last will and testament or by operation
of law to any interest  (including,  without  limitation,  a community  property
interest) of the spouse in the Membership Interest,  such Member shall have, and
may exercise within 60 days after the death of the spouse, an option to purchase
all or any  portion of the  spouse's  interest  for the price and upon the other
terms hereinafter  provided.  If the Member fails, within such 60-day period, to
exercise his purchase option (by delivery of written notice) with respect to the
entirety of such spouse's interest,  that Member shall be deemed to have elected
not to exercise his purchase option with respect to such spouse's interest. Upon
any notice of non-exercise (or deemed  non-exercise)  by the Member,  the Option
Members shall then have,  and may exercise  within 30 days after receipt of such
non-exercise (or deemed non-exercise),  an option to purchase all or any portion
of the  deceased  spouse's  interest,  for the price  and upon the  other  terms
hereinafter  provided. If the Option Members fail, within such 30-day period, to
exercise their purchase  option (by delivery of written  notice) with respect to
the entirety of such deceased  spouse's  interest,  the Option  Members shall be
deemed to have  elected not to exercise  their  purchase  option with respect to
such unpurchased deceased spouse's interest. Upon any notice of non-exercise (or
deemed  non-exercise) by the Option Members,  Prime shall have, and may exercise
within  30  days  of  receipt  of  notice  of  such   non-exercise   (or  deemed
non-exercise),  an option  to  purchase  all of such  remaining  portion  of the
deceased  spouse's  interest for the price and upon the other terms  hereinafter
provided.

             2.4.2Termination of Marital  Relationship or Partition of Community
Property. In the event a divorce,  annulment or other proceeding for termination
of the  marital  relationship  is  filed by or  against  a  Member,  or upon the
initiation  of any voluntary or  involuntary  attempt to partition the community
property  estate between a Member and such Member's  spouse for any reason,  the
Member shall  promptly give written  notice to the other  Members and Prime,  of
such event.  The Member shall have, and may exercise within 60 days of giving of
such notice, an option to purchase all or any portion of the departing  spouse's
interest in such Membership Interest (including without limitation any community
property  interest,  for purposes of this  Section),  for the price and upon the
other  terms  hereinafter  provided.  If the Member  fails,  within  such 60-day
period,  to exercise  his purchase  option (by delivery of written  notice) with
respect to the entirety of such spouse's  interest,  that Member shall be deemed
to have  elected  not to  exercise  his  purchase  option  with  respect to such
spouse's interest.  Upon any notice of non-exercise (or deemed  non-exercise) by
the Member,  the Option Members shall then have, and may exercise within 30 days
after  receipt  of such  non-exercise  (or  deemed  non-exercise),  an option to
purchase all or any portion of the departing  spouse's  interest,  for the price
and upon the other  terms  hereinafter  provided.  If the Option  Members  fail,
within such 30-day period,  to exercise  their  purchase  option (by delivery of
written  notice)  with  respect  to the  entirety  of  such  departing  spouse's
interest,  the Option  Members  shall be deemed to have  elected not to exercise
their  purchase  option  with  respect to such  unpurchased  departing  spouse's
interest. Upon any notice of non-exercise (or deemed non-exercise) by the Option
Members,  Prime shall have, and may exercise within 30 days of receipt of notice
of such non-exercise (or deemed non-exercise), an option to purchase all of such
remaining portion of the departing  spouse's interest for the price and upon the
other terms hereinafter provided.

2.5      ALTERNATE NOTICES.

             The failure of any  person,  whether a party to this  Agreement  or
otherwise,  to give notice of the occurrence of an Exercise Event (as defined in
Section 4.3) as contemplated herein shall not operate to prevent the creation of
any option which would otherwise arise pursuant to this ARTICLE II. Any party to
this  Agreement who has actual  knowledge of the occurrence of an Exercise Event
may give the required written notice of the occurrence of an Exercise Event, and
upon the giving of such written  notice the options  shall be created and become
exercisable  to the  same  extent  as if such  notice  was  given  by the  party
initially contemplated above. For instance, and purely by way of example, in the
event of the death of a Member,  another  Member having actual  knowledge of the
Member's  death  may give the  notice  initially  contemplated  to be given by a
representative  of the estate of the deceased  Member  pursuant to Section 2.3.1
above,  whereupon the Option  Members'  option  described in Section 2.3.2 would
arise and become  exercisable to the same extent as if the notice had been given
by the representative of the estate of the deceased Member.

2.6      OPPORTUNITY TO CURE.

         Before Prime may exercise any option to purchase a Membership  Interest
pursuant to Sections 2.2, 2.3 or 2.4, Prime shall deliver  written notice of its
intent to exercise its right ("Cure  Notice") to the Option  Members,  who shall
have ten days from the date of receipt  of such Cure  Notice to  exercise  their
rights and purchase such Membership  Interest,  upon such terms as are otherwise
provided  herein.  If each of the Option  Members do not  exercise  their rights
within ten days after  receipt of the Cure  Notice,  then Prime may exercise its
options under this Article II.

                                   ARTICLE III

                   EXERCISE OF OPTIONS; EFFECT OF NON-EXERCISE

3.1      MANNER OF EXERCISE OF OPTIONS.

             All options granted in, or arising pursuant to, ARTICLE II shall be
exercised by a written notice to that effect  delivered within the time provided
for the exercise of the option.

3.2      COMPLETE EXERCISE OF OPTIONS.

             Notwithstanding  anything  herein to the  contrary,  the holders of
options granted in, or arising pursuant to, ARTICLE II must,  either alone or in
the  aggregate,  exercise the options in such a manner as to purchase all of the
Membership  Interest (or interest therein) subject to such options,  and failure
to do so shall cause a forfeiture of the options.

3.3      MULTIPLE OPTION HOLDERS.

             In cases  where an option is held by more than one  Option  Member,
each  purchasing  Option  Member  shall  be  entitled  to  purchase  his  or her
proportionate  share of the Membership Interest subject to the option. An Option
Member's  proportionate  share  shall  equal  the  total  amount  of  Membership
Interests  subject to the option multiplied by a fraction the numerator of which
is the  amount  of  Membership  Interests  held by such  Option  Member  and the
denominator  of which shall be the amount of  Membership  Interests  held by all
Option Members electing to exercise the option.

3.4      EFFECT OF NON-EXERCISE OF OPTIONS.

             If the  holders of options  granted  or  arising  pursuant  to this
Agreement do not exercise  their  options,  or such  options are  forfeited,  as
provided herein,  the person or persons  acquiring the Membership  Interests (or
interest  therein)  that  were  the  subject  of the  options  shall  execute  a
counterpart  of this  Agreement  and  become a party  hereto and shall hold such
Membership  Interests  subject to all the terms and conditions  provided herein,
and any transfer of such Membership  Interests (or interest  therein) shall only
be made in accordance  with the terms and  conditions  provided  herein.  In the
event the person or persons  acquiring  the  Membership  Interests  (or interest
therein)  fail to execute a  counterpart  of this  Agreement  and become a party
hereto,  such transfer shall be void and  ineffectual,  and shall not operate to
transfer any interest or title to the purported  transferee and such  Membership
Interests shall thereafter be subject to cancellation and  extinguishment by the
Company,  without  consideration  therefor.  In  addition,  in  the  event  of a
voluntary  transfer  subject to the provisions of Section 2.1, upon the lapse or
forfeiture of the options arising pursuant to that Section, the Member proposing
the  transfer  shall have the right to  effectuate  the  transfer of  Membership
Interests  in  accordance  with the  terms  stated  in the  notice  of intent to
transfer,  and the  transferee of such  Membership  Interests  shall execute and
become a party to this  Agreement  and  shall  hold  such  Membership  Interests
subject to all of its terms and conditions.  Provided further, however, any such
transfer of Membership  Interests shall be void and  ineffectual,  and shall not
operate to transfer any interest or title to the  purported  transferee,  if (i)
the  transfer  is not upon the terms or is not to the  transferee  stated in the
notice of intent to transfer,  or (ii) the transfer is not closed within 10 days
of receipt of written notice of the election not to exercise,  or the forfeiture
of, all applicable options.

                                   ARTICLE IV

                                 PURCHASE PRICE

4.1      PURCHASE PRICE.

             The  purchase  price of the  Membership  Interests  to be purchased
pursuant to options granted, held or exercised pursuant to Sections 2.2, 2.3 and
2.4  hereof,  shall be the amount  calculated  in  accordance  with  Section 4.2
hereof.

4.2      CALCULATION OF PURCHASE PRICE.

             When  determined in accordance  with this Section 4.2, the purchase
price for the Membership  Interest or any portion  thereof or spouse's  interest
therein shall be equal to the Appraised  Value of the Membership  Interest as of
the Valuation Date (as defined in Section 4.3 hereof), reduced when necessary to
reflect the purchase of less than a one hundred  percent (100%) interest in each
of the Membership Interests to be transferred (for example:  reduced by one-half
when a  spouse's  interest  is only an  undivided  one-half  community  property
interest in each of the Membership  Interests of a Member spouse).  For purposes
of this Agreement,  the "Appraised Value" of a Membership  Interest shall be (i)
based on the overall value of the Company as a going concern, expressed in a per
Membership Interest unit amount without  consideration to whether the Membership
Interest,  or interest therein,  being transferred  constitutes a controlling or
minority  interest in the Company,  and (ii) determined by a certified  business
appraiser,  selected  by the  Company,  that is a member of either the  American
Society of Appraisers or the Institute of Business  Appraisers;  but if a Member
or Prime  disagrees  with such  determination  that  Member or Prime may, at its
expense,  have another certified  business  appraiser that is a member of one or
both of the above named professional  organizations  determine the value, and if
the two appraisers cannot agree upon a value, they shall mutually select a third
certified  business  appraiser  (that  meets  the  above  described   membership
requirements) who shall,  together with the first two appraisers,  determine the
value of the  Membership  Interest by majority  vote.  The expense of such third
appraiser  shall  also be paid by the  Member or Prime,  as the case may be, who
disagrees  with the value  determination  of the Company's  original  appraiser,
unless the appraised value ultimately  determined is more than ten percent (10%)
greater than the value determined by the Company's original appraiser.

4.3      CERTAIN DEFINITIONS.

             As used herein,  the term "Valuation  Date" shall mean and refer to
the end of the fiscal year of the Company  immediately  preceding  the  Exercise
Event,  unless the purchasing party elects to use the alternate  valuation date,
in which  event the  Valuation  Date  shall be the end of the month  immediately
preceding the Exercise  Event. As used herein,  the term "Exercise  Event" shall
mean and refer to the event or  circumstance  described  in  ARTICLE  II of this
Agreement, as a result of which the Company, a Member, or Prime, as the case may
be in the first  instance,  becomes  entitled  to  exercise  a  purchase  option
hereunder.

                                    ARTICLE V

                          PAYMENT OF THE PURCHASE PRICE

5.1      PAYMENT.

             Except as otherwise  provided in this Agreement,  including Section
2.1, the purchase price for a Membership Interest to be purchased from a selling
party shall either: (i) be paid in cash; or (ii) at the option of the purchasing
party,  up to seventy  percent (70%) of the purchase  price may be deferred with
the remainder paid in cash at the closing.

5.2      PROMISSORY NOTE.

             If the purchasing  party elects to defer part of the purchase price
by the execution and delivery of a promissory  note, the deferred portion of the
price shall be evidenced by the promissory  note of the purchasing  party to the
order of the selling party payable in sixty (60) equal monthly  installments  of
principal  and interest on or before the first day of each month  beginning  the
month next following the date of closing. The interest rate for such installment
promissory  note shall be equal to the prime or base rate on corporate  loans at
large U.S.  money center  commercial  banks as  published  in the "Money  Rates"
column of the Wall  Street  Journal  on the date of  exercise  of the  option to
purchase  (or, if such option is not  exercised  on a date on which such rate is
published, the next following date on which such rate is published). In no event
shall the interest rate exceed the maximum legal  interest rate then  prevailing
for such obligations in the state of Texas. The note shall be secured by a first
lien security interest in the Membership Interest transferred and the purchasing
party shall  deliver  certificates  evidencing  the  Membership  Interest to the
selling party and take such further action as is reasonably necessary to perfect
the security interest.

                                   ARTICLE VI

                                   THE CLOSING

             Unless otherwise agreed by the parties, the closing of the sale and
purchase of a Membership  Interest shall take place at the principal  offices of
the Company within sixty (60) days after the exercise of any option  provided by
this Agreement.  Each party hereto  (including the spouses of the Members) shall
bear its own transaction  costs,  including  legal and accounting  fees, if any,
attributable to any transfer of a Membership Interest,  or any interest therein,
pursuant to this  Agreement.  Upon the closing,  the selling party shall deliver
its  Membership  Interest  to the  purchaser  free and  clear of all  liens  and
encumbrances,  and shall deliver to the Company its  resignation and that of all
of its nominees, if any, as officers and directors of the Company and any of the
Company's subsidiaries.  The selling party shall deliver to the purchasing party
at closing, all appropriate documents of transfer,  including without limitation
bills of sale, assignments or other instruments of conveyance. As a condition to
any closing of the sale and purchase of a  Membership  Interest (or any interest
therein) pursuant to this Agreement:  (i) the selling party shall be indemnified
by the purchasing party (in a form reasonably satisfactory to the selling party)
for all the Company's liabilities,  whether fixed or contingent,  to lenders and
others,  incurred prior to the closing of the  transaction,  (ii) the purchasing
party and/or the Company  shall cause the release of any personal  guaranties by
the  selling  party that the  selling  party may have  granted to the  Company's
lenders or other  creditors  or which may have  otherwise  been  provided by the
selling party for the benefit of the Company,  and (iii) if the selling party is
a creditor of the Company, the purchasing party shall unconditionally  guarantee
the debt of the Company to the  selling  party and execute  such  documents  and
instruments   of  guarantee  as  may  be  necessary  in  connection   therewith.
Furthermore,  and as a condition to closing, in the event the selling party owes
any amounts to the Company at the time of closing,  such  indebtedness  shall be
paid in full by the selling party at or prior to the closing, or may be deducted
from and offset  against the  purchase  price by the  purchasing  party,  in the
purchasing  party's  sole  discretion.  In the event of a failure  to close as a
result of the  non-satisfaction  of the  conditions to closing set forth herein,
this  Agreement  shall  remain  in full  force  and  effect  and all  Membership
Interests  shall remain  subject to the  restrictions  contained  herein and, in
addition,  the parties hereto shall be entitled to such other remedies as may be
available in the event the failure to close constitutes a breach hereof.

                                   ARTICLE VII

                             LEGEND ON CERTIFICATES

             All Membership  Interests now or hereafter owned by the Members, or
their  permitted  transferees,  shall  be  subject  to the  provisions  of  this
Agreement,  and any  certificates  representing  same shall  bear the  following
legend:

             "THE  MEMBERSHIP   INTEREST   REPRESENTED   HEREBY  AND  THE  SALE,
             ASSIGNMENT,  TRANSFER,  PLEDGE  OR OTHER  DISPOSITION  THEREOF  ARE
             SUBJECT TO CERTAIN RESTRICTIONS  CONTAINED IN A MEMBERSHIP INTEREST
             TRANSFER  RESTRICTION  AGREEMENT  AMONG THE  COMPANY AND THE WITHIN
             NAMED MEMBER, AND ANY AMENDMENT  THERETO.  THE AGREEMENT LIMITS THE
             USE OF THIS MEMBERSHIP  INTEREST AS COLLATERAL FOR ANY LOAN WHETHER
             BY PLEDGE,  HYPOTHECATION  OR OTHERWISE.  A COPY OF THE  MEMBERSHIP
             INTERES   TRANSFER   RESTRICTION   AGREEMENT  AND  ALL   APPLICABLE
             AMENDMENTS  THERETO  WILL BE FURNISHED BY THE COMPANY TO THE HOLDER
             HEREOF  WITHOUT  CHARGE UPON WRITTEN  REQUEST TO THE COMPANY AT ITS
             PRINCIPAL PLACE OF BUSINESS OR REGISTERED OFFICE."

                                  ARTICLE VIII

                            TERMINATION OF AGREEMENT

             This Agreement and all restrictions on Membership Interest transfer
created hereby shall terminate on the occurrence of any of the following events:

             (a)  The bankruptcy or dissolution of the Company.

             (b) The ownership by one person of all of the Membership  Interests
of the Company which are then subject to this Agreement.

             (c) The execution of a written  instrument  by the Company,  all of
the Members who then own Membership  Interests  subject to this  Agreement,  and
Prime which terminates the same.

             (d) The date  twenty-one  (21)  years  after  the death of the last
survivor of all individuals who are parties to this Agreement.

                                   ARTICLE IX

                               GENERAL PROVISIONS

9.1      REMEDIES FOR BREACH.

             The  Membership  Interests are unique  chattels,  and each party to
this Agreement shall have the remedies which are available to him, her or it for
the violation of any of the terms of this Agreement,  including, but not limited
to, the equitable remedy of specific performance.

9.2      BINDING EFFECT.

             This  Agreement  is binding  upon and inures to the  benefit of the
Company,  its  successors  and  permitted  assigns,  to the  Members  and  their
respective heirs,  personal  representatives,  successors and permitted assigns,
and to Prime,  its successors and permitted  assigns.  This Agreement may not be
assigned,  in whole or in part, by any party hereto without the express  written
consent of all parties hereto.

9.3      PRIOR AGREEMENTS.

             This  Agreement  supersedes  all prior written and oral  agreements
between the parties regarding the subject matter hereof.

9.4      GOVERNING LAWS.

             This Agreement is executed under,  and in conformity with, the laws
of the State of Texas and shall be governed  thereby.  If any  provision of this
Agreement  shall be determined to be invalid or  unenforceable  or prohibited by
the laws of the State of Texas, this Agreement shall be considered  divisible as
to such provisions and such  provisions  shall be inoperative and shall not be a
part of the consideration  moving from any party to another party. The remaining
provisions  shall be valid and binding upon the parties and be of like effect as
though such invalid,  unenforceable  or prohibited  provisions were not included
herein.

9.5      AMENDMENT.

             This  Agreement  may be  amended  in whole  or in part  only by the
written consent of all the parties.  Such amendment shall be effective as of the
date then  determined by the parties and shall  supersede any provisions  herein
contained which are in conflict.

9.6      CAPTIONS AND GENDER.

             The captions and titles herein are for convenience only and are not
intended to include or  conclusively  define the subject matter of the text. All
pronouns and  references  thereto shall refer to the  masculine,  feminine,  and
neuter  genders,  singular  or plural,  as the  identification  of the  persons,
entities, and companies may require. The term "person" as used in this Agreement
shall include natural persons, companies,  partnerships, trusts, estates and any
other form of entity.

9.7      NOTICES.

             All notices  required to be given  hereunder  shall be deemed to be
duly given by  personally  delivering  such notice or by mailing it by certified
mail, to the Company,  to the Members,  and to Prime at the following  addresses
(which  may be  changed  by giving  written  notice of such  change to all other
parties hereto):

             To the Company:                        MBC Holding Company, L.L.C.
                                                    1200 Binz, Suite 1000
                                                    Houston, Texas 77004

             To Mann:                               Paul Michael Mann, M.D.
                                                    1200 Binz, Suite 1000
                                                    Houston, Texas 77004

             To Berkeley:                           Ralph G. Berkeley, M.D.
                                                    1200 Binz, Suite 1000
                                                    Houston, Texas 77004

             To Caplan:                             Michael B. Caplan, M.D.
                                                    1200 Binz, Suite 1000
                                                    Houston, Texas 77004

             To Micheletti:                         Mark F. Micheletti
                                                    1200 Binz, Suite 1000
                                                    Houston, Texas 77004

             To Prime:                              Prime RVC, Inc.
                                                    Attention: President
                                                    1301 Capital of
                                                        Texas Highway
                                                    Austin, Texas 78746

9.8  BINDING EFFECT OF THIS AGREEMENT ON ADDITIONAL MEMBERSHIP INTEREST ACQUIRED
     BY A MEMBER.

             In the event a Member acquires,  contracts to acquire,  or receives
any Membership  Interests of the Company which are not subject to this Agreement
at the time of acquisition,  such additional  Membership Interests of the Member
shall  be   automatically   subject  to  this  Agreement  and  any  certificates
representing  such Membership  Interests shall bear the legend prescribed herein
and this Agreement shall be amended, if necessary, to reflect the acquisition of
such Membership Interests by the Member.

9.9      EXECUTION OF DOCUMENTS.

             Whenever Membership Interests are to be purchased by the Company, a
Member, or Prime pursuant to this Agreement,  the transferor shall do all things
and execute and deliver all documents and make all transfers as may be necessary
to consummate such purchase.  In the event that the transferor  refuses to abide
by the terms and  conditions  specified  herein,  the  purchaser(s)  may  tender
payment  for such  Membership  Interest by mailing  payment to the  transferor's
attention  at the  address  of the  Company's  registered  office on file at the
office of the Texas Secretary of State.  After payment is tendered  accordingly,
the Company shall be entitled to cancel such  Membership  Interest on its books,
and reissue such Membership Interest to the purchaser(s) or, if the purchaser is
the Company,  the Company may hold such Membership Interest as treasury stock or
cancel such Membership Interest.

9.10     ACTIONS BY THE COMPANY.

             Any decision by the Company to exercise any purchase  option,  give
any notice or otherwise enforce any provisions of this Agreement,  shall be made
by a majority  vote of Members who are not then in breach of this  Agreement and
whose Membership Interests are not then the subject of any option or requirement
of notice of an Exercise Event.

                            [Signature pages follow]

<PAGE>

                                       S-2

                                SIGNATURE PAGE TO

                               MEMBERSHIP INTEREST

                         TRANSFER RESTRICTION AGREEMENT

             EXECUTED as of the date first mentioned above.

             COMPANY:                       MBC Holding Company, L.L.C.

                                                By:
                                                Printed Name:__________________
                                                Title:

         MANN:

                                                     Paul Michael Mann, M.D.

         BERKELEY:

                                                     Ralph G. Berkeley, M.D.

         CAPLAN:

                                                     Michael B. Caplan, M.D.

         MICHELETTI:

                                                     Mark F. Micheletti

         PRIME:                             Prime RVC, Inc.

                                                  By:
                                                  Printed Name:
                                                  Title:

<PAGE>

                                SPOUSAL CONSENTS

             The  undersigned   spouse  of  Paul  Michael  Mann,  M.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the membership  interest of MBC Holding Company,  L.L.C.,  referred to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                            Signature:
                                            Printed Name:

             The  undersigned  spouse  of  Ralph  G.  Berkeley,   M.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the membership  interest of MBC Holding Company,  L.L.C.,  referred to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                            Signature:
                                            Printed Name:

             The  undersigned  spouse  of  Michael  B.  Caplan,   M.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the membership  interest of MBC Holding Company,  L.L.C.,  referred to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                            Signature:
                                            Printed Name:

             The undersigned  spouse of Mark F. Micheletti  hereunto  subscribes
her name in evidence of her agreement and consent to the disposition made of any
interest  she may have,  including  any  community  property  interests,  in the
membership interest of MBC Holding Company, L.L.C., referred to in the foregoing
Agreement, and to all other provisions of such Agreement.

                                            Signature:
                                            Printed Name:

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