Document:

PRIME MEDICAL SERVICES, INC.

                           FOURTH AMENDED AND RESTATED

                                 LOAN AGREEMENT

                      $86,000,000.00 REVOLVING CREDIT LOAN

                              BANK OF AMERICA, N.A.

                             as Administrative Agent

                                BANKBOSTON, N.A.

                             as Documentation Agent

                                       and

                            THE LENDERS NAMED HEREIN,

                                   as Lenders

                          Dated as of January 31, 2000

                         BANC OF AMERICA SECURITIES LLC

                        as Lead Arranger and Book Manager

<PAGE>

                                 LOAN AGREEMENT

                                       vii

                                TABLE OF CONTENTS

ARTICLE I --  DEFINITIONS......................................................2
         Section 1.1       Amendment and Restatement...........................2
         Section 1.2       Definitions.........................................2
         Section 1.3       Other Definitional Provisions......................22

ARTICLE II --  ADVANCES.......................................................23
         Section 2.1       Commitments........................................23
         Section 2.2        Notes.............................................23
         Section 2.3       Repayment of Advances..............................23
         Section 2.4       Interest...........................................23
         Section 2.5       Borrowing Procedure................................24
         Section 2.6       Continuations; Conversions.........................24
         Section 2.7       Use of Proceeds....................................25
         Section 2.8       Fees...............................................25

ARTICLE III --  PAYMENTS......................................................25
         Section 3.1       Method of Payment..................................25
         Section 3.2       Optional Prepayment................................25
         Section 3.3       Mandatory Prepayments..............................26
         Section 3.4       Pro Rata Treatment.................................26
         Section 3.5       Non-Receipt of Funds by the Administrative Agent...26
         Section 3.6       Withholding Taxes..................................26
         Section 3.7       Withholding Tax Exemption..........................27
         Section 3.8       Computation of Interest............................27
         Section 3.9       Order of Application...............................27

ARTICLE IV --  YIELD PROTECTION AND ILLEGALITY................................28
         Section 4.1       Additional Costs...................................28
         Section 4.2       Limitation on Eurodollar Advances..................29
         Section 4.3       Illegality.........................................29
         Section 4.4       Treatment of Eurodollar Advances...................30
         Section 4.5       Compensation.......................................30
         Section 4.6       Capital Adequacy...................................31

ARTICLE V --  SECURITY........................................................31
         Section 5.1       Collateral.........................................31
         Section 5.2       Future Liens. .....................................32
         Section 5.3       Release of Collateral..............................33
         Section 5.4       Setoff.............................................33

ARTICLE VI --  CONDITIONS PRECEDENT...........................................33
                  Section 6.1       Initial Advance...........................33
         Section 6.2       All Advances.......................................35

ARTICLE VII --  REPRESENTATIONS AND WARRANTIES................................36
         Section 7.1       Existence..........................................36
         Section 7.2       Financial Statements...............................36
         Section 7.3       Corporate Action:  No Breach.......................37
         Section 7.4       Operation of Business..............................37
         Section 7.5       Litigation and Judgments...........................37
         Section 7.6       Rights in Properties; Liens........................37
         Section 7.7       Enforceability.....................................37
         Section 7.8       Approvals..........................................37
         Section 7.9       Debt...............................................38
         Section 7.10      Taxes..............................................38
         Section 7.11      Use of Proceeds; Margin Securities.................38
         Section 7.12      ERISA..............................................38
         Section 7.13      Disclosure.........................................38
         Section 7.14      Subsidiaries; Partnerships.........................38
         Section 7.15      Agreements.........................................39
         Section 7.16      Compliance with Legal Requirements;
                                 Governmental Authorizations..................39
         Section 7.17      Investment Company Act.............................40
         Section 7.18      Public Utility Holding Company Act.................40
         Section 7.19      Environmental Matters..............................40
         Section 7.20      Year 2000 Compliance...............................40

ARTICLE VIII --  POSITIVE COVENANTS...........................................40
         Section 8.1       Reporting Requirements.............................40
         Section 8.2       Maintenance of Existence; Conduct of Business......43
         Section 8.3       Maintenance of Properties..........................43
         Section 8.4       Taxes and Claims...................................43
         Section 8.5       Insurance..........................................43
         Section 8.6       Inspection Rights..................................44
         Section 8.7       Keeping Books and Records..........................44
         Section 8.8       Compliance with Laws...............................44
         Section 8.9       Compliance with Agreements.........................44
         Section 8.10      Further Assurances.................................44
         Section 8.11      ERISA..............................................44
         Section 8.12      Information Relating to Proposed Acquisitions......44
         Section 8.13      After-Acquired Subsidiaries........................44
         Section 8.14      Syndication Cooperation............................45

ARTICLE IX --  NEGATIVE COVENANTS.............................................45
         Section 9.1A      Debt...............................................45
         Section 9.1B      Debt of Refractive Entities........................46
         Section 9.2       Limitation on Liens................................46
         Section 9.3       Mergers, Etc.......................................46
         Section 9.4       Restricted Payments................................47
         Section 9.5       Investments........................................47
         Section 9.6       Limitation on Issuance of Capital Stock............49
         Section 9.7       Transactions With Affiliates.......................49
         Section 9.8       Disposition of Assets.  ...........................49
         Section 9.9       Sale and Leaseback.................................50
         Section 9.10      Prepayment of Debt.................................50
         Section 9.11      Nature of Business.................................50
         Section 9.12      Environmental Protection...........................50
         Section 9.13      Accounting.........................................50
         Section 9.14      Amendment of Partnership
                                and Management Agreements.....................50
         Section 9.15      Financial Hedges...................................50
         Section 9.16      Control of Prime Refractive, L.L.C.................51

ARTICLE X --  FINANCIAL COVENANTS.............................................51
         Section 10.1      Total Net Funded Debt to EBITDA....................51
         Section 10.2      Senior Net Funded Debt To EBITDA Ratio.............51
         Section 10.3      Debt Service Coverage Ratio........................51
         Section 10.4      Consolidated Net Worth.............................52

ARTICLE XI --  DEFAULT........................................................52
         Section 11.1      Events of Default..................................52
         Section 11.2      Remedies...........................................54
         Section 11.3      Performance by the Administrative Agent............54

ARTICLE XII --  THE ADMINISTRATIVE AGENT......................................55
         Section 12.1      Appointment, Powers and Immunities.................55
         Section 12.2      Rights of Administrative Agent as a Lender.........56
         Section 12.3      Sharing of Payments, Etc...........................56
         Section 12.4      Indemnification....................................57
         Section 12.5      Independent Credit Decisions.......................57
         Section 12.6      Several Commitments................................58
         Section 12.7      Successor Administrative Agent.....................58
         Section 12.8      Independent Contractor.............................58

ARTICLE XIII --  MISCELLANEOUS................................................59
         Section 13.1      Expenses...........................................59
         Section 13.2      Indemnification....................................59
         Section 13.3      No Duty............................................59
         Section 13.4      No Fiduciary Relationship..........................60
         Section 13.5      No Waiver; Cumulative Remedies.....................60
         Section 13.6      Successors and Assigns.............................60
         Section 13.7      Survival...........................................62
         Section 13.8      ENTIRE AGREEMENT...................................62
         Section 13.9      Amendments, Etc....................................63
         Section 13.10     Maximum Interest Rate..............................63
         Section 13.11     Notices............................................63
         Section 13.12     Governing Law......................................64
         Section 13.13     Counterparts.......................................64
         Section 13.14     Severability.......................................64
         Section 13.15     Headings...........................................64
         Section 13.16     Construction.......................................64
         Section 13.17     Independence of Covenants..........................64
         Section 13.18     Confidentiality....................................64
         Section 13.19     Restatement of Original Credit Agreement...........65
         Section 13.20     Assignments and Assumptions Among Lenders.  .......65
         Section 13.21     Waiver of Jury Trial...............................65
         Section 13.22     Choice of Forum; Consent to Service
                                of Process and Jurisdiction. .................65
         Section 13.23     Chapter 346........................................66

<PAGE>

                                INDEX TO EXHIBITS

Exhibit           Description of Exhibit

A                 Advance Request Form
B                 Form of Assignment and Acceptance
C                 Form of Note
D                 Perfection Certificate

E                 Form of Opinion of Counsel for Borrower and the Guarantors
F                 Compliance Certificate
G                 Permitted Acquisition Certificate
H                 Permitted Passive Investment Certificate
I                 Permitted Other Business Acquisition Certificate
J                 Permitted Refractive Acquisition Certificate
K                 Non-Borrower and Guarantor Acquisition Certificate
L                 Form of Subordinated Note
M                 Form of Subordination Agreement

                               INDEX TO SCHEDULES

Schedule Description of Schedule

1                 Commitments
2                 Guarantors
3                 Partnerships
7.5               Existing Litigation
7.9               Existing Debt
7.14.1            Capitalization of Subsidiaries
7.14.2            Partners
7.15              Agreements
7.16              Governmental Disclosures
7.19              Environmental Matters
9.2               Existing Liens

<PAGE>

                                                                  LOAN AGREEMENT

                   FOURTH AMENDED AND RESTATED LOAN AGREEMENT

         THIS FOURTH  AMENDED AND RESTATED  LOAN  AGREEMENT  (the  "Agreement"),
dated as of January 31, 2000, is among PRIME MEDICAL SERVICES,  INC., a Delaware
corporation  ("Borrower"),  each of the  lenders or other  lending  institutions
which is or which  may  from  time to time  become  a  signatory  hereto  or any
successor or assignee thereof (collectively,  the "Lenders" and individually,  a
"Lender"),  BANK OF  AMERICA,  N.A.  ("Bank of  America"),  a  national  banking
association,  as Administrative  Agent for itself and the other Lenders (in such
capacity,  together with its  successors in such capacity,  the  "Administrative
Agent"), and BANKBOSTON, N.A. ("BankBoston"), a national banking association, as
Documentation Agent for itself and the other Lenders (in such capacity, together
with its successors in such capacity, the "Documentation Agent").

                                 R E C I T A L S

                  1.  Reference is hereby made to that  certain  Loan  Agreement
         dated as of  November  28,  1994,  by and between  Borrower,  the Banks
         defined therein,  and BankBoston (then known as The First National Bank
         of Boston),  as Agent for the Banks defined therein, as amended by that
         certain First  Amendment to Loan Agreement dated as of August 17, 1995,
         as amended by the Amended and Restated Loan Agreement dated as of April
         26, 1996 among Borrower,  BankBoston,  as Administrative Agent, Bank of
         America (then known as NationsBank of Texas,  N.A.),  as  Documentation
         Agent,  and BankBoston,  as Syndication  Agent, as amended by the First
         Amendment to Amended and Restated Loan  Agreement  dated as of June 14,
         1996 among  Borrower,  BankBoston,  as  Administrative  Agent,  Bank of
         America (then known as NationsBank of Texas,  N.A.),  as  Documentation
         Agent,  and the other banks named  therein,  as further  amended by the
         Second Amended and Restated Loan  Agreement  dated as of March 31, 1997
         among Borrower,  BankBoston,  as Administrative  Agent, Bank of America
         (then known as NationsBank of Texas, N.A.), as Documentation Agent, and
         NationsBanc  Capital Markets,  Inc., and the lenders named therein,  as
         amended and waived from time to time,  as further  amended by the Third
         Amended and Restated  Loan  Agreement  dated as of April 20, 1998 among
         Borrower, BankBoston, as original Administrative Agent and as successor
         Documentation  Agent,  Bank of America  (then known as  NationsBank  of
         Texas,  N.A.),  as  original   Documentation  Agent  and  as  successor
         Administrative  Agent,  and the lenders named  therein,  as amended and
         waived  from  time  to  time   (collectively,   the  "Original   Credit
         Agreement").

                  2.  Subject  to the terms  and  conditions  set  forth  below,
         Borrower and  "Required  Lenders"  (as defined in the  Original  Credit
         Agreement) desire to entirely amend,  modify,  and restate the Original
         Credit Agreement,  to provide for, among other things (a) a decrease in
         the maximum amount available under the Revolving  Credit  Commitment to
         $86,000,000,  and (b) modification and amendment to certain  provisions
         therein,  subject  to the  terms  and  conditions  set  forth  in  this
         Agreement.

                  3.  The  amendment  and  restatement  of the  Original  Credit
         Agreement hereunder is not intended by the parties to constitute either
         a novation or a  discharge  or  satisfaction  of the  indebtedness  and
         "Obligations"  under the Original Credit Agreement,  which indebtedness
         and  obligations  under the  Original  Credit  Agreement  shall  remain
         outstanding hereunder on the terms and conditions hereinafter provided.

<PAGE>

         In consideration  of the foregoing and the mutual  covenants  contained
herein, Borrower, Bank of America (in its capacity as Administrative Agent under
the Original  Credit  Agreement),  BankBoston (in its capacity as  Documentation
Agent under the  Original  Credit  Agreement)  and  Required  Lenders  under the
Original  Credit  Agreement  agree that,  effective  upon the Closing Date,  the
Original Credit Agreement is amended and restated in its entirety, as follows:

                            ARTICLE I -- DEFINITIONS

                  Section 1.1 Amendment and  Restatement.  This  Agreement is in
         renewal,  extension,  modification,  and  restatement  of the  Original
         Credit  Agreement and constitutes and is hereby  designated by Borrower
         as  "Designated  Senior  Debt" as defined  in the  Senior  Subordinated
         Indenture.

               Section 1.2 Definitions. As used in this Agreement, the following
          terms shall have the following meanings:

         "Acquisition"   means  any  transaction,   or  any  series  of  related
transactions,  consummated on or after the date hereof,  by which Borrower,  any
Guarantor,  or any other  Subsidiary  of  Borrower  directly or  indirectly  (a)
acquires all or substantially  all of the assets of any Person,  whether through
purchase of assets, merger, or otherwise, (b) acquires (in one transaction or as
the most recent transaction in a series of transactions) at least a majority (in
number of votes) of the  securities  (or  similar  ownership  interests)  of any
Person, or (c) acquires (in one transaction or as the most recent transaction in
a series of  transactions)  at least a majority  of the general  partnership  or
managing member interests of any Person, or (d) acquires additional  Partnership
or other equity interests in any Subsidiary.

         "Additional Costs" has the meaning specified in Section 4.1.

         "Adjusted EBITDA" means for any Person for any period,  the sum of: (i)
EBITDA,  except  in  the  case  of  any  Target  Company  in  respect  of  which
Consolidated  Earn-Out  Indebtedness  is payable,  EBITDA of such Target Company
shall be  increased  by the amount,  if any, by which such  Person's  annualized
fiscal year to date  EBITDA used in the  calculation  of  Consolidated  Earn-Out
Indebtedness, exceeds the actual EBITDA for the four previous fiscal quarters of
such  Person  for  such  period,  plus  (ii)  without   duplication,   all  cash
Distributions  related to minority interests in Partnership actually received by
Prime Refractive  Management,  L.L.C., plus (iii) without duplication,  on a pro
forma basis,  the EBITDA of any Target Company acquired during such period as if
it were acquired on the first day of such period.

         "Adjusted  Eurodollar Rate" means,  for any Eurodollar  Advance for any
Interest Period therefor, the rate per annum (rounded upwards, if necessary,  to
the nearest 0.01%) determined by the Administrative Agent to be equal to (a) the
Eurodollar Rate for such Eurodollar  Advance for such Interest Period divided by
(b) 1.00 minus the  Reserve  Requirement  for such  Eurodollar  Advance for such
Interest Period.

     "Administrative  Agent"  means Bank of  America,  N.A.,  and its  permitted
successors  and  assigns  as  "Administrative  Agent"  for  Lenders  under  this
Agreement.

         "Advance"  means each advance of funds by the Lenders or any of them to
Borrower pursuant to Section 2.5(a).

<PAGE>

         "Advance Request Form" means a certificate,  in substantially  the form
of Exhibit A, properly completed and signed by Borrower requesting an Advance.

         "Advancing  Term Loan Facility"  means the  $14,000,000  Advancing Term
Loan pursuant to the Loan Agreement dated the date hereof among Bank of America,
N.A., as Administrative  Agent,  BankBoston,  N.A., as Documentation  Agent, the
lenders  from  time to time  party  thereto,  and Prime  Refractive  Management,
L.L.C., as borrower.

         "Affiliate" means, as to any Person, any other Person (a) that directly
or indirectly, through one or more intermediaries, Controls or is Controlled by,
or is under common  Control with,  such Person,  (b) that directly or indirectly
beneficially  owns or holds  five  percent  (5%) or more of any  class of voting
stock of such  Person,  or (c) five  percent (5%) or more of the voting stock of
which is  directly  or  indirectly  beneficially  owned or held by the Person in
question;  provided,  however,  in no event  shall the  Agents or any  Lender be
deemed an Affiliate of Borrower or any of its Subsidiaries.

         "After-Acquired Subsidiary" has the meaning specified in Section 8.13.

     "Agents" means the Administrative  Agent, the Documentation  Agent, and the
Lead Arranger. "Agent" means any one of the Agents.

         "Alternate  Base  Rate"  means,  at any time,  the  greater  of (a) the
variable rate of interest  established  from time to time by the  Administrative
Agent as its  "base  rate"  and set by the  Administrative  Agent  as a  general
reference  rate of interest  charged by the  Administrative  Agent,  and (b) the
Federal Funds Rate plus  one-half of one percent  (.5%).  Borrower  acknowledges
that the  Administrative  Agent may,  from time to time,  extend credit to other
borrowers at rates of interest varying from, and having no relationship to, such
general  reference  rate.  Each change in the  Alternate  Base Rate shall become
effective  without prior notice to Borrower  automatically  as of the opening of
business on the date of such change in the Alternate Base Rate.

         "Alternate  Base Rate  Advances"  means  Advances that bear interest at
rates based upon the Alternate Base Rate.

         "Applicable  Lending  Office"  means for each  Lender  and each Type of
Advance,  the lending  office of such Lender (or of an Affiliate of such Lender)
designated for such Type of Advance below its name on the signature pages hereof
or an Assignment and  Acceptance,  or such other office of such Lender (or of an
Affiliate  of such  Lender)  as such  Lender  may from time to time  specify  to
Borrower  and the  Administrative  Agent as the office by which its  Advances of
such Type are to be made and maintained.

         "Applicable  Margin" means the interest  margin over the Alternate Base
Rate or the Adjusted Eurodollar Rate, as the case may be, for Advances under the
Commitment  (a) from the date hereof until the delivery of financial  statements
and a  compliance  certificate  for the period  ending  December  31,  1999,  as
required  hereunder,  one-half of one percent  (.500%) for  Alternate  Base Rate
Advances,  and two percent (2.000%) for Eurodollar Advances; and (b) thereafter,
based on the Net Total Funded Debt to EBITDA Ratio as of and for the most recent
four (4)  quarter  period  ending on or before  the date of  determination,  the
margin set forth opposite such ratio below:

<PAGE>

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

   Applicable Margin

    Net Total Funded              Alternate Base Rate       Applicable Margin
   Debt to EBITDA Ratio               Advances             Eurodollar Advances

-------------------------- --------------------------- -------------------------
-------------------------- --------------------------- -------------------------

Less than 1.5 to 1.0                   .375%                      1.375%
-------------------------- --------------------------- -------------------------
-------------------------- --------------------------- -------------------------

-------------------------- --------------------------- -------------------------
-------------------------- --------------------------- -------------------------

-------------------------- --------------------------- -------------------------
-------------------------- --------------------------- -------------------------

Greater than or
  equal to 2.75 to 1.0                .875%                      2.375%
========================== =========================== =========================

The Net Total Funded Debt to EBITDA Ratio shall be determined from the then most
current of either (a) the quarterly or annual  financial  statements and related
compliance certificate delivered pursuant to Section 8.1, or (b) the most recent
Advance Request Form for a Permitted Acquisition,  Permitted Passive Investment,
Permitted  Other  Business  Acquisition,  or Permitted  Refractive  Acquisition,
calculating  any  adjustments  to such  ratio  necessitated  as a result  of the
Permitted  Acquisition,  Permitted Passive Investment,  Permitted Other Business
Acquisition,  or Permitted  Refractive  Acquisition,  for which such Advance was
made.  The  adjustment,  if any, to the  Applicable  Margin  shall be  effective
commencing  on the fifth (5th)  Business  Day after  delivery of such  financial
statements  (and  related  compliance  certificate)  or the  respective  date of
Advance for a Permitted  Acquisition,  Permitted Passive  Investment,  Permitted
Other Business Acquisition, or Permitted Refractive Acquisition, as the case may
be. If Borrower fails at any time to furnish to the Administrative Agent and the
Lenders the financial statements and related compliance  certificate as required
to be delivered  pursuant to Section  8.1,  then the maximum  Applicable  Margin
shall  apply  until  such  time  as such  financial  statements  and  compliance
certificates are so delivered.

         "Applicable  Rate"  means:  (a) during any period that an Advance is an
Alternate Base Rate Advance, the Alternate Base Rate plus the Applicable Margin;
and (b) during any period that an Advance is a Eurodollar Advance,  the Adjusted
Eurodollar Rate plus the Applicable Margin.

         "Applicable  Unused  Fee  Percentage"  means  the per  annum  rate with
respect to the unused portion of the  Commitments as follows:  (a) from the date
hereof until delivery of financial  statements and a compliance  certificate for
the period  ending  December  31,1999,  as required  hereunder,  one-half of one
percent  (.500%);  and (b)  thereafter,  based on the Net Total  Funded  Debt to
EBITDA Ratio as of and for the most recent four (4) quarter  period ending on or
before the date of  determination,  the percentage set forth opposite such ratio
below:

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

                  Net Total Funded                      Applicable Unused Fee
                 Debt to EBITDA Ratio                         Percentage

------------------------------------------------------ -------------------------
------------------------------------------------------ -------------------------

               Less than 1.5 to 1.0                              .300%
------------------------------------------------------ -------------------------
------------------------------------------------------ -------------------------

    Less than 2.0 to 1.0 but greater than or equal to            .375%
           1.5 to 1.0

    Greater than or equal to 2.0 to 1.0                          .500%
====================================================== =========================

<PAGE>

The Applicable  Unused Fee Percentage  shall be adjusted,  if necessary,  at the
same time as adjustments to the Applicable Margin. If Borrower fails at any time
to furnish to the Administrative  Agent and the Lenders the financial statements
and related  compliance  certificate  as required  to be  delivered  pursuant to
Section 8.1, then the maximum Applicable Unused Fee Percentage shall apply until
such  time as such  financial  statements  and  compliance  certificates  are so
delivered.

         "Assignee" has the meaning specified in Section 13.6.

         "Assigning Lender" has the meaning specified in Section 13.6.

         "Assignment and Acceptance" means an assignment and acceptance  entered
into by an Assigning Lender and its Assignee and accepted by the  Administrative
Agent pursuant to Section 13.6, in substantially the form of Exhibit B.

     "Bank of America" means Bank of America,  N.A. and its permitted successors
and assigns.

     "BankBoston"  means  BankBoston,  N.A.  and its  permitted  successors  and
assigns.

         "Basle  Accord" means the proposals for  risk-based  capital  framework
described  by  the  Basle  Committee  on  Banking  Regulations  and  Supervisory
Practices  in  its  paper   entitled   "International   Convergence  of  Capital
Measurement and Capital  Standards" dated July,  1988, as amended,  supplemented
and  otherwise  modified  and in effect  from time to time,  or any  replacement
thereof.

         "BDEC  Acquisition"  means the  acquisition by PMOI of an undivided 60%
interest  in the  "refractive  surgery"  assets of Barnet  Dulaney  Eye  Center,
P.L.L.C., and the contribution by PMOI of such assets to Prime/BDEC Acquisition,
L.L.C.

         "Borrower Security Agreement" means (a) the Borrower Security Agreement
dated as of April 26,  1996,  executed by Borrower  in favor of  BankBoston,  as
predecessor  Administrative Agent to Administrative Agent for the benefit of the
Lenders,  as the same may be amended,  supplemented,  or  modified  from time to
time,  including  (b) the Consent,  Confirmation  and  Ratification  of Borrower
Security  Agreement  dated  as of  March  31,  1997,  (c)  the  Second  Consent,
Confirmation and Ratification of Borrower  Security  Agreement dated as of April
20, 1998, and (d) the Third Consent,  Confirmation  and Ratification of Borrower
Security  Agreement  dated  as of  the  date  hereof,  which  Borrower  Security
Agreement is in renewal, amendment, restatement and substitution of that certain
Borrower  Security  Agreement  dated November 28, 1994,  executed by Borrower in
favor of  BankBoston,  as  predecessor  Administrative  Agent to  Administrative
Agent,  for the benefit of the Lenders under the Original Credit  Agreement,  as
amended pursuant to that First Amendment to Borrower Security Agreement dated as
of August 17, 1995, and any other security  agreement executed from time to time
by Borrower  and  delivered to the  Administrative  Agent for the benefit of the
Lenders, all as amended, renewed, restated, and substituted from time to time.

         "Business Day" means (a) any day on which the  Administrative  Agent is
open for regular  business,  and (b) with respect to all  borrowings,  payments,
Conversions,  Continuations,  Interest  Periods,  and notices in connection with
Eurodollar  Advances,  any day which is a Business  Day  described in clause (a)
above and which is also a day on which  dealings in Dollar  deposits are carried
out in the London interbank market.

<PAGE>

         "Capital Lease Obligations" means, as to any Person, the obligations of
such Person to pay rent or other  amounts  under a lease of (or other  agreement
conveying the right to use) real and/or personal property, which obligations are
required to be  classified  and  accounted  for as a capital  lease on a balance
sheet of such Person under GAAP. For purposes of this  Agreement,  the amount of
such Capital Lease  Obligations  shall be the  capitalized  amount  thereof,  as
determined in accordance with GAAP.

         "Cash  Equivalent"  means any  investments  of the Companies  which are
permitted by Section  9.5(a),  and which  mature  within 180 days of any date of
determination,  and which are  unconditionally  available  for  repayment of the
Obligations, upon liquidation.

         "Change in Control"  means a Change of Control as defined in the Senior
Subordinated Indenture.

         "Code" means the Internal  Revenue  Code of 1986,  as amended,  and the
regulations promulgated and rulings issued thereunder.

         "Collateral" has the meaning specified in Section 5.1.

         "Collateral  Documents"  means the  Borrower  Security  Agreement,  the
Guarantor Security Agreements,  the Pledge Agreements, and all other collateral,
security,  lien  creating  agreements  executed or  delivered  pursuant to or in
connection with this Agreement, as the same may be amended,  modified,  renewed,
or supplemented from time to time.

         "Commitment" means, as to each Lender as of any date, the obligation of
such Lender on such date to make  Advances  hereunder in an aggregate  principal
amount at any time  outstanding  up to but not  exceeding  the  amount  shown on
Schedule 1 as its  Commitment,  as the same may be reduced  pursuant  to Section
2.1(b) or terminated  pursuant to Section 2.1(b) or Section 11.2 and as the same
may be increased or decreased from time to time by further  assignment  pursuant
to Section 13.6.  "Commitments"  means the  Commitments of all of the Lenders in
the original aggregate amount of $86,000,000.00.

         "Companies" means Borrower and its Subsidiaries.

         "Confidential  Information"  means any and all information  relating to
the Companies,  including,  without limitation,  information relating to each of
the Company's financial condition, business plans, management, earnings, assets,
liabilities,   contracts,   processes,   products,   research  and   development
activities, intellectual property, services, customers, suppliers, marketing and
sales.  In addition,  Confidential  Information  shall include any and all other
information  marked  or  identified  in  writing  by  any of  the  Companies  as
"Confidential"  or  "Confidential  Information"  and  provided  by  each  of the
Companies or its representatives to any of the Lenders or the Agents or obtained
by the  Lenders or the  Agents  after an  inspection  pursuant  to Section  8.6.
Notwithstanding the foregoing, "Confidential Information" shall not include:

                  (i) any  information  known to an  Agent or a Lender  prior to
         disclosure  by  any  of  the  Companies  or  its  representatives,   as
         documented prior to such disclosure in such Agent's or Lender's written
         records;

<PAGE>

                  (ii) any information  which an Agent or a Lender  demonstrates
         became available to it on a non-confidential basis from a source (other
         than  any of the  Companies)  who is  not  bound  by a  confidentiality
         agreement with, or any other contractual, legal or fiduciary obligation
         of  confidentiality  to, any of the  Companies  or any other party with
         respect to such information;

                  (iii) any information which an Agent or a Lender  demonstrates
         is or becomes generally  available to the public other than as a result
         of a disclosure by it in breach of Section 13.18; and

                  (iv) any information  which an Agent or a Lender  demonstrates
         was  conceived of or developed  by it or any of its  employees  without
         access  or  reference,  directly  or  indirectly,  to the  Confidential
         Information.

         "Consolidated  Earn-Out  Indebtedness"  means as to any Person,  at any
time, in connection with each  applicable  Permitted  Refractive  Acquisition in
which an earn-out payment or other post-closing payment or payments is or may be
due pursuant to the applicable purchase or acquisition agreement,  the projected
aggregate  amount of such  earn-out or  post-closing  payments  that would be or
become due based upon all events or  circumstances  that have occurred as of any
date of determination, regardless of whether any such payments are then actually
payable under the terms of the  applicable  purchase or  acquisition  agreement;
provided that to the extent any such payments are based on net income, revenues,
EBITDA or similar  financial  performance  criteria of any Target  Company for a
defined   post-closing  period  or  periods,  the  actual  applicable  financial
performance  during the  applicable  period to date shall be  utilized in making
such projection.  Borrower shall submit the calculation of Consolidated Earn-Out
Indebtedness with respect to each applicable Permitted  Refractive  Acquisition,
together with each compliance  certificate delivered pursuant to Section 8.1(d),
together  with any  applicable  supporting  documentation,  all of which must be
satisfactory to Administrative Agent.

         "Consolidated  Net Income"  means,  for any Person for any period,  the
amount which, in conformity with GAAP,  would be shown on a consolidated  income
statement of such Person as net income for such period,  after  deduction of any
minority interests.

         "Consolidated  Net Worth" means,  at any  particular  time, all amounts
which, in conformity with GAAP, would be included as  stockholders'  equity on a
consolidated balance sheet of the Companies.

         "Continue,"  "Continuation," and "Continued" refers to the continuation
pursuant to Section 2.6 of a Eurodollar  Advance from one Interest Period to the
next Interest Period.

         "Control" means the possession, directly or indirectly, of the power to
direct or cause the direction of the management or policies of a Person, whether
through the ownership of voting  securities  or other  ownership  interests,  by
contract or otherwise.  "Controlling" and "Controlled" have meanings correlative
thereto.

         "Conversion" and "Converted" refers to a conversion pursuant to Section
2.6 of one Type of Advance into another Type of Advance.

<PAGE>

         "Debt"  means as to any  Person at any time  (without  duplication  and
without duplication among the Companies): (a) all obligations of such Person for
borrowed money;  (b) all obligations of such Person  evidenced by bonds,  notes,
debentures,  or other similar instruments,  including,  without limitation,  the
Senior  Subordinated  Notes;  (c)  all  obligations  of such  Person  to pay the
deferred purchase price of property or services,  including, without limitation,
Consolidated Earn-Out Indebtedness, except trade accounts payable of such Person
arising in the  ordinary  course of business  that are not past due by more than
ninety (90) days;  (d) all Capital  Lease  Obligations  of such Person;  (e) all
indebtedness  or other  obligations  of others of the  types  described  in this
definition, if Guaranteed by such Person or for which such Person is liable as a
partner in any  partnership  or joint  venturer  in any joint  venture;  (f) all
obligations secured by a Lien existing on property owned by such Person, whether
or not the  obligations  secured thereby have been assumed by such Person or are
non-recourse to the credit of such Person; (g) all reimbursement  obligations of
such Person  (whether  contingent or otherwise) in respect of letters of credit,
banker's  acceptances,  surety or other bonds and similar  instruments;  (h) all
obligations under any Financial Hedge, and (i) all liabilities of such Person in
respect of unfunded vested benefits under any Plan; provided,  however, that the
term  Debt  shall  not  include  endorsements  of  instruments  for  deposit  or
collection in the ordinary course of business.

         "Debt Service Coverage Ratio" means, as to the Companies  (including on
a pro forma basis any Company acquired in any Permitted  Acquisition,  Permitted
Other Business Acquisition,  or Permitted Refractive Acquisition for each of the
components of and for the entire period of calculation of Debt Service  Coverage
Ratio) for any period, the ratio of (a) the sum of: (i) Adjusted EBITDA for such
period, minus (ii) the aggregate amount of capital expenditures made during such
period,  minus (iii) all cash tax  payments,  divided by (b) the sum of: (w) all
cash interest  payments payable during such period in respect of all Debt of the
Companies  (without deduction for any minority  interests),  plus (x) 1/7 of the
outstanding   principal   amount  of  the  Loans  and  1/7  of  the  outstanding
"Obligations"  under  the  Advancing  Term  Loan  Facility  as of  any  date  of
determination,  plus (y) 1/7 of the Consolidated Earn-Out Indebtedness as of any
date of determination,  plus (z) any regularly  scheduled  principal payments on
Debt (including Subordinated Debt, but excluding Earn-Out Indebtedness),  all as
determined  on a rolling four (4) quarter and  consolidated  basis in accordance
with GAAP.

         "Default"  means an Event of Default or the  occurrence  of an event or
condition  which  with the  giving of notice or the lapse of time or both  would
become an Event of Default.

         "Default  Rate" means the lesser of (a) the Maximum  Rate,  and (b) the
sum of the  Alternate  Base Rate in effect  from day to day plus the  Applicable
Margin plus two percent (2%).

         "Defaulting  Lender"  means any Lender that in  Administrative  Agent's
reasonable  judgment  has  defaulted  on  any  of  its  obligations  under  this
Agreement.

         "Documentation  Agent"  means  BankBoston,   N.A.,  and  its  permitted
successors  and  assigns  as  "Documentation   Agent"  for  Lenders  under  this
Agreement.

         "Dollars" and "$" mean lawful money of the United States of America.

         "EBITDA" means,  for any Person for any period:  (a)  Consolidated  Net
Income  of such  Person  for such  period,  determined  after  deduction  of any
minority interests,  plus (b) all amounts deducted therefrom during such period,
in conformity with GAAP, for interest,  taxes,  depreciation  and  amortization,
provided  that  cash flow  from  Permitted  Passive  Investments  shall  only be
included in the  calculation  of EBITDA to the extent:  (i) it has been actually
received by Borrower or a Guarantor, and (ii) it does not exceed fifteen percent
(15%) of total EBITDA for such period.

<PAGE>

         "Eligible  Assignee" means (i) a Lender; (ii) an Affiliate of a Lender;
or (iii) any other Person approved by the  Administrative  Agent (which approval
shall not be  unreasonably  withheld  or delayed by  Administrative  Agent) and,
unless  an Event of  Default  has  occurred  and is  continuing  at the time any
assignment is effected in accordance with Section 13.6, Borrower,  such approval
not to be  unreasonably  withheld or delayed by Borrower and such approval to be
deemed given by Borrower if no objection is received by the assigning Lender and
the Administrative Agent from Borrower within two (2) Business Days after notice
of such  proposed  assignment  has been  provided  by the  assigning  Lender  to
Borrower;  provided, however, that neither Borrower nor an Affiliate of Borrower
shall qualify as an Eligible Assignee.

     "Environmental  Laws"  means any and all  federal,  state,  and local laws,
regulations,  and requirements pertaining to health, safety, or the environment,
including,   without  limitation,  the  Comprehensive   Environmental  Response,
Compensation and Liability Act of 1980, 42 U.S.C.ss.  9601 et seq., the Resource
Conservation  and  Recovery  Act  of  1976,  42  U.S.C.ss.  6901  et  seq.,  the
Occupational  Safety and Health Act, 29 U.S.C.ss.651 et seq., the Clean Air Act,
42 U.S.C.ss.  7401 et seq., the Clean Water Act, 33 U.S.C.ss.  1251 et seq., and
the Toxic  Substances  Control  Act,  15  U.S.C.ss.2601  et seq.,  as such laws,
regulations, and requirements may be amended or supplemented from time to time.

         "Environmental  Liabilities"  means, as to any Person, all liabilities,
obligations,  responsibilities,  Remedial  Actions,  losses,  damages,  punitive
damages,  consequential damages, treble damages, costs, and expenses (including,
without limitation,  all reasonable fees, disbursements and expenses of counsel,
expert and consulting fees and costs of investigation and feasibility  studies),
fines, penalties,  sanctions,  and interest incurred as a result of any claim or
demand,  by any Person,  whether  based in  contract,  tort,  implied or express
warranty,   strict   liability,   criminal  or  civil  statute,   including  any
Environmental Law, permit, order or agreement with any Governmental Authority or
other Person,  arising from  environmental,  health or safety  conditions or the
Release or  threatened  Release of a Hazardous  Material  into the  environment,
resulting  from the past,  present,  or future  operations of such Person or its
Affiliates.

         "ERISA" means the Employee  Retirement  Income Security Act of 1974, as
amended from time to time,  and the  regulations  and published  interpretations
thereunder.

         "ERISA Affiliate" means any corporation or trade or business which is a
member of the same  controlled  group of  corporations  (within  the  meaning of
Section 414(b) of the Code) as Borrower or is under common  control  (within the
meaning of Section 414(c) of the Code) with Borrower.

         "Eurodollar  Advances"  means  Advances the interest rates on which are
determined on the basis of the rates  referred to in the definition of "Adjusted
Eurodollar Rate" in this Section 1.1.

         "Eurodollar  Rate" means,  for any Eurodollar  Advance for any Interest
Period  therefor,  the rate per annum  (rounded  upwards,  if necessary,  to the
nearest 1/100 of 1%) appearing on Telerate Page 3750 (or any successor  page) as
the London interbank offered rate for deposits in Dollars at approximately 11:00
a.m.  (London  time) two Business  Days prior to the first day of such  Interest
Period for a term  comparable  to such Interest  Period.  If for any reason such
rate is not available, the term "Eurodollar Rate" shall mean, for any Eurodollar
Advance for any Interest Period therefor,  the rate per annum (rounded  upwards,
if necessary,  to the nearest 1/100 of 1%) appearing on Reuters Screen LIBO Page
as the London  interbank  offered rate for deposits in Dollars at  approximately
11:00  a.m.  (London  time)  two  Business  Days  prior to the first day of such
Interest  Period  for a term  comparable  to  such  Interest  Period,  provided,
however,  if more than one rate is  specified on Reuters  Screen LIBO Page,  the
applicable rate shall be the arithmetic mean of all such rates.

         "Event of Default" has the meaning specified in Section 11.1.

     "Excepted   Subsidiaries"   means   FastStart,   Inc.,  a  North   Carolina
corporation,   National  Lithotripters   Association,   Inc.  a  North  Carolina
corporation, and MedTech Investments, Inc., a North Carolina corporation.

<PAGE>

         "Exchange  Notes" means those certain senior  subordinated  notes to be
issued  in  exchange  for  the  originally  issued  Senior  Subordinated  Notes,
containing  substantially  the same terms as the  original  Senior  Subordinated
Notes.

         "Existing Permitted Passive Investments" means ownership by Borrower or
any Subsidiary of a 32.5% interest in Southern California Stone Center,  L.L.C.,
a California  limited  liability  company and a 38.25% interest in TENN-GA Stone
Group Two, a Tennessee general partnership.

         "Federal  Funds Rate" means,  for any day, the rate per annum  (rounded
upwards,  if necessary,  to the nearest 0.01%) equal to the weighted  average of
the rates on overnight  Federal funds  transactions  with members of the Federal
Reserve  System  arranged by Federal  funds brokers on such day, as published by
the Federal  Reserve Bank of New York on the Business Day next  succeeding  such
day, provided that (a) if the day for which such rate is to be determined is not
a Business  Day, the Federal  Funds Rate for such day shall be such rate on such
transactions  on the next  preceding  Business  Day as so  published on the next
succeeding  Business  Day, and (b) if such rate is not so published on such next
succeeding Business Day, the Federal Funds Rate for any day shall be the average
rate charged to the  Administrative  Agent on such day on such  transactions  as
determined by the Administrative Agent.

         "Financial Hedge" means either (a) a swap, collar, floor, cap, or other
contract  which is intended to reduce or eliminate the risk of  fluctuations  in
interest rates, or (b) a foreign exchange,  currency hedging, commodity hedging,
or other  contract  which is intended to reduce or eliminate  the market risk of
holding  currency or a commodity  in either the cash or futures  markets,  which
Financial  Hedge  under  either  clause  (a) or clause  (b) is  entered  into by
Borrower with any Lender or an Affiliate of any Lender.

         "GAAP" means generally  accepted  accounting  principles,  applied on a
consistent basis, as set forth in Opinions of the Accounting Principles Board of
the American  Institute of Certified Public  Accountants and/or in statements of
the Financial Accounting Standards Board and/or their respective  successors and
which are applicable in the circumstances as of the date in question. Accounting
principles are applied on a "consistent  basis" when the  accounting  principles
applied in a current  period are  comparable  in all material  respects to those
accounting principles applied in a preceding period, except for changes required
by GAAP.  In the event of a change in GAAP,  Administrative  Agent and  Borrower
will  thereafter  negotiate  in good  faith  to  revise  any  covenants  of this
Agreement affected thereby in order to make such covenants  consistent with GAAP
then in effect.

         "Governmental  Authority" means any nation or government,  any state or
political subdivision thereof and any entity exercising executive,  legislative,
judicial,   regulatory,   or  administrative   functions  of  or  pertaining  to
government.

         "Governmental Authorization" shall mean any approval, consent, license,
permit, waiver, or other authorization issued, granted, given, or otherwise made
available by or under the authority of any Governmental Authority or pursuant to
any Legal Requirement.

<PAGE>

         "Guarantee"  by  any  Person  means  any   obligation,   contingent  or
otherwise,  of such Person directly or indirectly guaranteeing any Debt or other
obligation  of any other  Person and,  without  limiting the  generality  of the
foregoing, any obligation,  direct or indirect, contingent or otherwise, of such
Person (a) to purchase or pay (or  advance or supply  funds for the  purchase or
payment  of)  such  Debt or other  obligation  (whether  arising  by  virtue  of
partnership arrangements,  by agreement to keep-well, to purchase assets, goods,
securities  or services,  to  take-or-pay,  or to maintain  financial  statement
conditions or otherwise), or (b) entered into for the purpose of assuring in any
other manner the obligee of such Debt or other obligation of the payment thereof
or to protect the obligee against loss in respect thereof (in whole or in part),
provided that the term "Guarantee" shall not include endorsements for collection
or deposit in the ordinary course of business.  The term  "Guarantee"  used as a
verb has a corresponding meaning.

         "Guaranties" means,  collectively,  (a) the Guaranty  Agreements,  each
dated as of April 26,  1996,  executed by certain  Guarantors,  (b) the Consent,
Confirmation  and  Ratification  of Guaranty  Agreements,  dated as of March 31,
1997, executed by certain Guarantors,  (c) the Second Consent,  Confirmation and
Ratification  of  Guaranty  Agreements  dated as of April 20,  1998  executed by
certain Guarantors,  (d) the Consent,  Confirmation and Ratification of Guaranty
Agreements  dated as of April 20, 1998 executed by certain  Guarantors,  (e) the
Guaranty Agreement dated as of March 31, 1997 executed by Prostatherapies, Inc.,
(f) the Guaranty Agreements, each dated April 20, 1998 executed by each Excepted
Subsidiary and Executive Medial  Enterprises,  Inc., (g) the Guaranty  Agreement
dated  as of the  date  hereof  executed  by each  Guarantor;  certain  of which
Guaranty Agreements are in renewal,  amendment,  substitution and replacement of
the Guaranty Agreements executed by certain Guarantors under the Original Credit
Agreement  in favor of the  Agent and the  Lenders  under  the  Original  Credit
Agreement  and shall also include any other  guaranty  agreement  heretofore  or
hereafter  from time to time  executed by any  Guarantor  and  delivered  to the
Administrative Agent for the benefit of Lenders, as amended, restated,  renewed,
and substituted from time to time. "Guaranty" means any one of the Guaranties.

         "Guarantors"  means,  collectively,  all  Wholly-Owned  Subsidiaries of
Borrower,  now  owned  or  hereafter  acquired  or  formed,  including,  without
limitation,  the Subsidiaries  listed on Schedule 2, other than Prime Refractive
Management, L.L.C. "Guarantor" means any one of the Guarantors.

         "Guarantor Security Agreements" means (a) the Security Agreements, each
dated as of April 26,  1996,  executed by certain  Guarantors,  (b) the Consent,
Confirmation and Ratification of Guarantor Security Agreements dated as of March
31, 1997, executed by certain Guarantors,  (c) the Second Consent,  Confirmation
and  Ratification  of Guarantor  Security  Agreement dated as of April 20, 1998,
executed by certain Guarantors,  (d) the Consent,  Confirmation and Ratification
of  Guarantor  Security  Agreements  dated as of the date  hereof,  executed  by
certain  Guarantors,  (e) the  Security  Agreement  dated as of March 31,  1997,
executed by  Prostatherapies,  Inc., (f) the Guarantor Security Agreements dated
April 20, 1998  executed  by each  Excepted  Subsidiary  and  Executive  Medical
Enterprises,  Inc.,  (g) the  Security  Agreement  dated as of the  date  hereof
executed by each Guarantor each in favor of Administrative Agent for the benefit
of Lenders,  certain of which  Security  Agreements  are in renewal,  amendment,
restatement  and  substitution  of the Security  Agreements  executed by certain
Guarantors  under the Original Credit  Agreement in favor of the  Administrative
Agent, for the benefit of the Lenders under the Original Credit  Agreement,  and
shall also include any other  security  agreements  heretofore or hereafter from
time to time executed by any Guarantor and delivered to the Administrative Agent
for the benefit of Lenders, as amended, restated,  renewed, and substituted from
time to time.  "Guarantor  Security  Agreement"  means any one of the  Guarantor
Security Agreements.

         "Hazardous Material" means any substance,  product,  waste,  pollutant,
material,  chemical,  contaminant,  constituent,  or other  material which is or
becomes listed,  regulated, or addressed under any Environmental Law, including,
without limitation, asbestos, petroleum, and polychlorinated biphenyls.

     "Horizon  Acquisition"  means the  acquisition  by  Prime/BDR  Acquisition,
L.L.C. of 60% of the stock of Horizon Vision Center, Inc.

<PAGE>

         "Immediately-available"  means  that any cash or Cash  Equivalents  are
capable of being liquidated  (without premium,  penalty,  or restriction) within
180 days of any date of determination, are not subject to any Liens or claims of
third persons, and are unconditionally  available for payment of the Obligations
upon liquidation.

         "Interest Period" means, with respect to any Eurodollar  Advance,  each
period  commencing on the date such Advance is made or Converted from an Advance
of another Type or, in the case of each subsequent,  successive  Interest Period
applicable to a Eurodollar Advance,  the last day of the next preceding Interest
Period with respect to such Advance, and ending on the numerically corresponding
day in the first (1st),  second (2nd), third (3rd) or sixth (6th) calendar month
thereafter,  as Borrower  may select as  provided in Section 2.5 or 2.6,  except
that each such  Interest  Period which  commences on the last  Business Day of a
calendar  month (or on any day for which there is no  numerically  corresponding
day in the appropriate subsequent calendar month) shall end on the last Business
Day of the appropriate subsequent calendar month. Notwithstanding the foregoing:
(a) each  Interest  Period  which  would  otherwise  end on a day which is not a
Business  Day  shall  end on the  next  succeeding  Business  Day  (or,  if such
succeeding Business Day falls in the next succeeding calendar month, on the next
preceding  Business Day); (b) any Interest Period which would  otherwise  extend
beyond the Termination Date shall end on the Termination  Date; (c) no more than
six (6)  Interest  Periods  shall  be in  effect  at the same  time;  and (d) no
Interest  Period  shall have a duration  of less than one (1) month and,  if any
Interest Period would otherwise be a shorter period,  such Advances shall not be
available hereunder.

         "Issuance  Proceeds"  means  the net cash  proceeds  of (i) any sale or
issuance of Borrower's capital stock,  excluding any sale or issuance of capital
stock under Borrower's stock option plans, or (ii) the incurrence of any Debt of
the type described in  subsections  (a) and (b) of the definition of Debt (other
than the  Senior  Subordinated  Notes),  in each  case to the  extent  permitted
hereunder.

         "Lead Arranger" means Bank of America Securities L.L.C.

         "Legal Requirement" shall mean any federal,  state,  local,  municipal,
foreign,   international,   multinational,   or  other   administrative   order,
constitution,  law, ordinance, principle of common law, regulation,  statute, or
treaty as in effect on the date hereof.

         "Lenders"   mean,   on  any  date  of   determination,   the  financial
institutions named on Schedule 2.1 (as the same may be amended from time to time
by  Administrative  Agent to reflect the  assignments  made in  accordance  with
Section 13.6(b) of this  Agreement),  and subject to the terms and conditions of
this  Agreement,  and  their  respective  successors  and  assigns  (but not any
Participant  who is not  otherwise a party to this  Agreement);  provided  that,
solely for purposes of any  Collateral  Documents  and Section 12, and "Lenders"
shall  also  include  any  Lender  or  Affiliate  of a Lender  who is party to a
Financial Hedge with Borrower and their  respective  successors and assigns (for
purposes hereof, each Lender shall be deemed to have entered into this Agreement
for and on behalf of any Affiliate now or hereafter  party to a Financial  Hedge
with Borrower).

         "Lien" means any lien, mortgage, security interest, tax lien, financing
statement, pledge, charge, hypothecation,  assignment,  preference, priority, or
other  encumbrance  of  any  kind  or  nature  whatsoever  (including,   without
limitation, any conditional sale or title retention agreement),  whether arising
by contract, operation of law, or otherwise.

         "Litho" means Lithotripters, Inc., a North Carolina corporation.

<PAGE>

         "Loan" means all Advances with respect to the Commitment,  evidenced by
the Notes.

         "Loan Documents" means this Agreement,  the Notes, the Guaranties,  the
Borrower  Security  Agreement,  the Guarantor  Security  Agreements,  the Pledge
Agreements, any Financial Hedge documents, and all other instruments, documents,
and  agreements  executed and delivered  pursuant to or in connection  with this
Agreement,  as such  instruments,  documents,  and  agreements  may be  amended,
modified, renewed, extended, or supplemented from time to time.

         "Material  Subsidiary" means, as of any date, (a) any Subsidiary which,
together with its  Subsidiaries,  accounts for three percent (3%) or more of the
Company's  consolidated  gross  revenues or assets,  or (b) any  combination  of
Subsidiaries which, together with their Subsidiaries,  account for seven percent
(7%) or more of the Company's  consolidated  gross  revenues or assets,  in each
case on a consolidated basis (but without elimination of any minority interests)
as of and for the most  recent  fiscal  quarter  for which such  information  is
available. "Material Subsidiaries" means all of the Material Subsidiaries.

         "Maximum Rate" means,  at any time and with respect to any Lender,  the
maximum  rate of  interest  under  applicable  law that such  Lender  may charge
Borrower.  The  Maximum  Rate shall be  calculated  in a manner  that takes into
account  any and all fees,  payments,  and other  charges in respect of the Loan
Documents  that  constitute  interest under  applicable  law. Each change in any
interest rate provided for herein based upon the Maximum Rate  resulting  from a
change in the Maximum Rate shall take effect  without  notice to Borrower at the
time of such change in the Maximum Rate.

         "Multiemployer  Plan" means a multiemployer  plan as defined in Section
3(37) of ERISA to which  contributions  have been made by  Borrower or any ERISA
Affiliate of Borrower and which is covered by Title IV of ERISA.

         "Net Total Funded Debt" means,  as of any date, the sum of: (a) Debt of
the Companies;  less (b) the amount of any  Immediately-available  cash and Cash
Equivalents held by the Companies in excess of $8,000,000 in the aggregate; plus
(c) the  amount  of all  cash  and  cash  equivalents  held by any  Company  for
distribution to any partners or other owners of equity interests (other than any
Company) in any Partnership.

         "Net Total  Funded Debt to EBITDA  Ratio"  means,  as of any date,  the
ratio of (a) the aggregate  amount of Net Total Funded Debt  (without  deduction
for any minority interests), outstanding as of such date, to (b) Adjusted EBITDA
of the  Companies,  for the four (4) fiscal quarter period ending on the date of
determination.

         "Note"   means  a   revolving   credit  note   executed  by   Borrower,
substantially  in the form of  Exhibit C,  payable  to each  Lender in an amount
equal to such  Lender's  Commitment,  as the same may be amended,  supplemented,
modified or restated from time to time, evidencing the obligation of Borrower to
repay the Loan, and all renewals,  modifications and extensions thereof. "Notes"
means all of the Notes of the Lenders.

         "Obligated  Party"  means any  Person  who is or  becomes  party to any
agreement that  guarantees or secures payment and performance of the Obligations
or any part thereof.

<PAGE>

         "Obligations" means all obligations,  indebtedness,  and liabilities of
Borrower to the Agents and the Lenders,  or any of them, arising pursuant to any
of the Loan  Documents,  now  existing or  hereafter  arising,  whether  direct,
indirect,  related,  unrelated,  fixed,  contingent,  liquidated,  unliquidated,
joint,  several, or joint and several, and all interest accruing thereon and all
attorneys'  fees and other  expenses  incurred in the  enforcement or collection
thereof;  provided that, all references to the  "Obligations"  in the Collateral
Documents, and in Section 12, shall, in addition to the foregoing,  also include
all present  and future  indebtedness,  liabilities,  and  obligations  (and all
renewals and  extensions  thereof or any part thereof) now or hereafter  owed to
any Lender or any Affiliate of a Lender  arising from, by virtue of, or pursuant
to any Financial Hedge entered into by any Company.

         "Original Credit Agreement" has the meaning specified in the recitals.

         "Partnerships"  means the partnerships and limited liability  companies
in which  Borrower or any  Subsidiary  now owns or  hereafter  acquires  general
and/or limited partnership interests or membership interests, including, without
limitation,   the   partnerships   and  other  Persons  listed  on  Schedule  3.
"Partnership" means any one of the Partnerships,  and shall also include any non
Wholly-Owned Subsidiary of Prime RVC or Prime Refractive Management, L.L.C.

         "Payment  Date" means (a) with respect to Alternate  Base Rate Advances
and the commitment fees payable  pursuant to Section  2.8(a),  the last Business
Day of each April, July,  October and January,  commencing January 31, 2000, and
(b) with respect to Eurodollar Advances, the last day of the respective Interest
Period therefor,  provided that if any Interest Period is greater than three (3)
months,  then accrued interest shall also be due and payable on the date that is
three (3) months after the commencement of such Interest Period.

         "PBGC" means the Pension  Benefit  Guaranty  Corporation  or any entity
succeeding to all or any of its functions under ERISA.

         "Permitted  Acquisition" means an Acquisition by Borrower or any of the
Guarantors  with respect to which each of the  following  conditions  shall have
been satisfied:

                  (a) the  Acquisition  by  Borrower or such  Guarantor  is of a
         business,  assets,  or Person (as  applicable,  the "Target")  which is
         engaged  in  substantially   the  same  lithotripsy   business  as  the
         lithotripsy  business  conducted  by Borrower or such  Guarantor on the
         date hereof, or any other business reasonably related thereto;

                  (b) as of the closing of such Acquisition, the Acquisition has
         been approved by the board of directors or other  applicable  governing
         body of the  Target  and the  Person  from  which  the  Target is to be
         acquired;

               (c) prior to the closing of such Acquisition,  the Target and the
          Person from which the Target is to be acquired must be Solvent;

                  (d) as of the closing of such Acquisition, after giving effect
         to such  Acquisition,  Borrower or the Guarantor  that is the acquiring
         party must be Solvent and the Companies,  on a consolidated basis, must
         be Solvent;

                  (e) as of the closing of such Acquisition, after giving effect
         to such  Acquisition,  no Default  shall exist or occur as a result of,
         and after giving effect to, such Acquisition;

<PAGE>

                  (f)  the  aggregate   purchase  price  with  respect  to  such
         Acquisition  does not  exceed  five (5)  times  EBITDA  of the  Target,
         subject to  adjustments  acceptable to the  Administrative  Agent where
         less  than  all of the  business,  assets  or stock  of the  Target  is
         acquired,  pursuant to the Acquisition for the four (4) fiscal quarters
         ending on the most  recently  ended fiscal  period prior to the date of
         such Acquisition;

                  (g) the aggregate nonstock  consideration for such Acquisition
         does  not  exceed   $20,000,000.00   (other  than  the  Acquisition  of
         additional ownership interests in the Partnerships in which Borrower or
         a Guarantor is, as if the date hereof,  the general partner or managing
         member)  and the  aggregate  cash  consideration  for all  Acquisitions
         (other than the  Acquisition of additional  ownership  interests of the
         Partnerships  in  which  Borrower  or a  Guarantor  is,  as of the date
         hereof,  the general partner or managing member) during the immediately
         preceding twelve (12) month period  (including such  Acquisition)  does
         not exceed $40,000,000.00;

                  (h) not less than 15 Business Days prior to the closing of any
         Acquisition,  the  Administrative  Agent shall have  received pro forma
         financial  statements of the  Companies (as if the business,  assets or
         Person  acquired  had been  acquired  since the first  (1st) day of the
         period for which such pro forma financial  statements are delivered and
         had been  managed  and  conducted  in  accordance  with the  Borrower's
         standard business  practices) for the prior four (4) fiscal quarters of
         Borrower and the Companies;

               (i)  as  of  the  closing  of  such  Acquisition,  Borrower  or a
          Guarantor shall Control the Target;

               (j) if the  Target is to be an  After-Acquired  Subsidiary,  then
          Borrower  shall have complied with the terms and  conditions set forth
          in Section 8.13;

                  (k) the absence of action, suit, investigation,  or proceeding
         pending  or  threatened  in any  court  or  before  any  arbitrator  or
         governmental  authority that affects the Target Company or the proposed
         Acquisition,  which  could  reasonably  be  expected to have a material
         adverse effect on the Target Company or the Borrower; and

                  (l) the Administrative  Agent has received a certificate dated
         on or  immediately  prior to the date of  Acquisition,  executed by the
         President  or  a  Vice  President  of  Borrower   confirming  that  all
         representations and warranties set forth in the Loan Documents continue
         to be true and correct in all material  respects  immediately  prior to
         and  after  giving  effect  to  the  Permitted   Acquisition   and  the
         transactions  contemplated  thereby, and setting forth the calculations
         supporting compliance with the limitations prescribed herein.

         "Permitted Other Business Acquisition" means an acquisition by Borrower
or any of the Guarantors with respect to which each of the following  conditions
shall have been satisfied:

                  (a) the  acquisition  by  Borrower or such  Guarantor  is of a
         business,  assets,  or Person (as  applicable,  the "Target")  which is
         engaged  in  substantially  the  same  physician  practice  management,
         prostatherapy,   or   servicing   tractor/trailers   business  as  such
         businesses are conducted by Borrower or any Company on the date hereof,
         or any other business reasonably related thereto;

<PAGE>

                  (b)  as of  the  closing  of  such  Permitted  Other  Business
         Acquisition, the Permitted Other Business Acquisition has been approved
         by the board of directors  or other  applicable  governing  body of the
         Target and the Person from which the Target is to be acquired;

               (c)  prior  to the  closing  of  such  Permitted  Other  Business
          Acquisition,  the Target and the Person from which the Target is to be
          acquired must be Solvent;

                  (d)  as of  the  closing  of  such  Permitted  Other  Business
         Acquisition,  after  giving  effect to such  Permitted  Other  Business
         Acquisition, Borrower or the Guarantor that is the acquiring party must
         be Solvent and the Companies, on a consolidated basis, must be Solvent;

                  (e)  as of  the  closing  of  such  Permitted  Other  Business
         Acquisition,  after  giving  effect to such  Permitted  Other  Business
         Acquisition,  no Default shall exist or occur as a result of, and after
         giving effect to, such Permitted Other Business Acquisition;

                  (f)  the  aggregate   purchase  price  with  respect  to  such
         Permitted  Other  Business  Acquisition  does not exceed five (5) times
         EBITDA  of  the  Target,  subject  to  adjustments  acceptable  to  the
         Administrative  Agent  where less than all of the  business,  assets or
         stock of the  Target  is  acquired,  pursuant  to the  Permitted  Other
         Business  Acquisition  for the four (4) fiscal  quarters  ending on the
         most recently  ended fiscal period prior to the date of such  Permitted
         Other Business Acquisition;

                  (g) the  aggregate  nonstock  consideration  for all Permitted
         Other  Business   Acquisitions   (other  than  the  acquisition  of  AK
         Associates,  which has been  previously  consented  to) does not exceed
         $5,000,000;

                  (h) not less than 15 Business Days prior to the closing of any
         Permitted Other Business  Acquisition,  the Administrative  Agent shall
         have  received pro forma  financial  statements of the Companies (as if
         the business,  assets or Person  acquired had been  acquired  since the
         first  (1st)  day of the  period  for which  such pro  forma  financial
         statements  are  delivered  and  had  been  managed  and  conducted  in
         accordance  with the Borrower's  standard  business  practices) for the
         prior four (4) fiscal quarters of Borrower and the Companies;

               (i) if the  Target is to be an  After-Acquired  Subsidiary,  then
          Borrower  shall have complied with the terms and  conditions set forth
          in Section 8.13;

                  (j) the absence of action, suit, investigation,  or proceeding
         pending  or  threatened  in any  court  or  before  any  arbitrator  or
         governmental  authority that affects the Target Company or the proposed
         Permitted  Other  Business  Acquisition,   which  could  reasonably  be
         expected to have a material adverse effect on the Target Company or the
         Borrower; and

                  (k) the Administrative  Agent has received a certificate dated
         on or  immediately  prior  to the  date  of  Permitted  Other  Business
         Acquisition,  executed by the President or a Vice President of Borrower
         confirming  that all  representations  and  warranties set forth in the
         Loan Documents continue to be true and correct in all material respects
         immediately  prior to and after giving  effect to the  Permitted  Other
         Business  Acquisition and the transactions  contemplated  thereby,  and
         setting  forth  the   calculations   supporting   compliance  with  the
         limitations prescribed herein.

<PAGE>

         The loan  described  in  Sections  9.1A(h)  and 9.2(h)  hereof  made by
Borrower  shall not be included in the  calculation  of the  aggregate  nonstock
consideration  for all Permitted Other Business  Acquisitions.  No repurchase or
redemption  of  Borrower's  capital  stock by Borrower or a  Guarantor,  whether
through  issuance and  performance of a put agreement,  or otherwise  shall be a
Permitted Other Business Acquisition.

         "Permitted Passive  Investment" means an acquisition by Borrower or any
of  the  Guarantors,  in one  transaction  or in a  series  of  transactions  of
partnership, stock, or other interests of a Person ("Equity Interests") which is
not an Acquisition and does not permit Borrower or any Guarantor to Control such
Person, with respect to which each of the following conditions have been met:

                  (a) the acquisition by Borrower or such Guarantor is of Equity
         Interests  of a Person  (the  "Passive  Target")  which is  engaged  in
         substantially the same lithotripsy business as the lithotripsy business
         conducted  by Borrower or such  Guarantor  on the date  hereof,  or any
         other lithotripsy business reasonably related thereto;

                  (b) as of the closing of such  Permitted  Passive  Investment,
         the  acquisition  has been  approved by the board of directors or other
         applicable  governing  body of the  Passive  Target and the Person from
         which the Equity Interests are to be acquired;

               (c) prior to the closing of such acquisition,  the Passive Target
          and the Person from which the Equity Interests are to be acquired must
          be Solvent;

                  (d) as of the closing of such  Permitted  Passive  Investment,
         after giving effect to such Permitted Passive  Investment,  Borrower or
         the  Guarantor  that is the  acquiring  party must be  Solvent  and the
         Companies, on a consolidated basis, must be Solvent;

                  (e) as of the closing of such  Permitted  Passive  Investment,
         after giving effect to such Permitted  Passive  Investment,  no Default
         shall exist or occur as a result of, and after  giving  effect to, such
         Permitted Passive Investment;

                  (f) the aggregate  acquisition  price of any Permitted Passive
         Investment,  together  with  the  original  purchase  price of all then
         existing  Permitted Passive  Investments of Borrower and its Guarantors
         (excluding,  however,  any prior  Permitted  Passive  Investment  which
         Borrower or any Guarantor then Controls) as of the date of consummation
         of the Permitted Passive Investment,  does not exceed the lesser of (i)
         twenty percent (20%) of Total Equity or (ii) $50,000,000;

                  (g) not less than 30 Business Days prior to the closing of any
         Permitted  Passive  Investment,  the  Administrative  Agent  shall have
         received a certificate setting forth compliance with condition (f), set
         forth above;

                  (h) the absence of action, suit, investigation,  or proceeding
         pending  or  threatened  in any  court  or  before  any  arbitrator  or
         governmental  authority that affects the Target Company or the proposed
         Permitted  Passive  Investment,  which could  reasonably be expected to
         have a material  adverse  effect on the Target Company or the Borrower;
         and

<PAGE>

                  (i) the Administrative  Agent has received a certificate dated
         on  or  immediately   prior  to  the  date  of  the  Permitted  Passive
         Investment,  executed by the President or a Vice  President of Borrower
         confirming  that all  representations  and  warranties set forth in the
         Loan Documents continue to be true and correct in all material respects
         immediately  prior to and after giving effect to the Permitted  Passive
         Investment and the transactions contemplated thereby, and setting forth
         the calculations  supporting compliance with the limitations prescribed
         herein.

No  repurchase  or  redemption  of  Borrower's  capital  stock by  Borrower or a
Guarantor,  whether  through  issuance and  performance of a put  agreement,  or
otherwise, shall be a Permitted Passive Investment.

               "Permitted  Refractive   Acquisition"  means  an  Acquisition  by
          Borrower, any Guarantor, Prime Refractive Management, L.L.C., or Prime
          Refractive,  L.L.C.,  with  respect  to  which  each of the  following
          conditions shall have been satisfied:

               (a) the  acquisition by Borrower,  Guarantors,  Prime  Refractive
          Management, L.L.C., or Prime Refractive, L.L.C. is of a Target Company
          which is engaged in the businesses of correcting  refractive  error of
          the eye, or any other business reasonably related thereto;

                  (b)  as  of  the   closing   of  such   Permitted   Refractive
         Acquisition,  the Permitted Refractive Acquisition has been approved by
         the board of directors or other applicable governing body of the Target
         Company and the Person from which the Target Company is to be acquired;

                  (c) prior to or at  closing,  the  closing  of such  Permitted
         Refractive  Acquisition,  the Target  Company and the Person from which
         the Target Company is to be acquired must be Solvent;

               (d) as of the closing of such Permitted  Refractive  Acquisition,
          after  giving  effect  to  such  Permitted   Refractive   Acquisition,
          Borrower,  the Guarantor that is the acquiring party, Prime Refractive
          Management,  L.L.C.,  or Prime Refractive  L.L.C., as the case may be,
          must be Solvent and the Companies,  on a consolidated  basis,  must be
          Solvent;

                  (e)  as  of  the   closing   of  such   Permitted   Refractive
         Acquisition,   after  giving  effect  to  such   Permitted   Refractive
         Acquisition,  no Default shall exist or occur as a result of, and after
         giving effect to, such Permitted Refractive Acquisition;

                  (f)  the  aggregate   purchase  price  with  respect  to  such
         Permitted  Refractive  Acquisition does not exceed six (6) times EBITDA
         of  the  Target  Company,  subject  to  adjustments  acceptable  to the
         Administrative  Agent  where less than all of the  business,  assets or
         stock of the Target  Company is  acquired,  pursuant  to the  Permitted
         Refractive  Acquisition  for the four (4) fiscal quarters ending on the
         most recently  ended fiscal period prior to the date of such  Permitted
         Refractive Acquisition;

                  (g) the  aggregate  nonstock  consideration  for any Permitted
         Refractive Acquisition (including, without limitation, any financing of
         interests  acquired  by  LASIK  Investors,   L.L.C.,  and  Consolidated
         Earn-Out Indebtedness  reasonably estimated by Administrative Agent and
         Borrower)  does not exceed  $10,000,000.00  and the aggregate  nonstock
         consideration  for  all  Permitted   Refractive   Acquisitions  in  the
         aggregate  financed  with  Advances   hereunder,   advances  under  the
         Advancing Term Loan Facility,  and Consolidated Earn-Out  Indebtedness,
         does not exceed $65,000,000;

<PAGE>

                  (h) not less than 15 Business Days prior to the closing of any
         Permitted Refractive  Acquisition,  the Administrative Agent shall have
         received pro forma  financial  statements  of the  Companies (as if the
         business,  assets or Person  acquired had been acquired since the first
         (1st) day of the period for which such pro forma  financial  statements
         are delivered and had been managed and conducted in accordance with the
         Borrower's  standard business  practices) for the prior four (4) fiscal
         quarters of Borrower and the Companies;

               (i) if the Target Company is to be an After-Acquired  Subsidiary,
          then Borrower  shall have complied with the terms and  conditions  set
          forth in Section 8.13;

                  (j) review by a third party  acceptable to the  Administrative
         Agent of Borrower's due diligence  process and procedures as related to
         Permitted Refractive  Acquisitions,  acceptable to Administrative Agent
         and Lenders;

                  (k) with respect to any Permitted Refractive Acquisition where
         the aggregate nonstock consideration is $10,000,000 or less (including,
         without  limitation,  any  financing  of  interests  acquired  by LASIK
         Investors,  L.L.C. and Consolidated  Earn-Out  Indebtedness  reasonably
         estimated by  Administrative  Agent and  Borrower),  the Target Company
         must, at a minimum,  provide company prepared financial  statements for
         the immediately  preceding four fiscal quarters  prepared in accordance
         with the due diligence procedures approved in (j) above;

               (l) the Target Company or other  business  segment being acquired
          must have positive pro forma trailing twelve month EBITDA;

               (m) the capital and  ownership  structure  of the Target  Company
          (after giving effect to the Permitted Refractive Acquisition) shall be
          satisfactory to the Administrative Agent;

                  (n) the absence of action, suit, investigation,  or proceeding
         pending  or  threatened  in any  court  or  before  any  arbitrator  or
         governmental  authority that affects the Target Company or the proposed
         Permitted Refractive Acquisition, which could reasonably be expected to
         have a material adverse effect on the Target Company or the Borrower;

                  (o) receipt of all governmental,  shareholder, and third party
         consents and approvals  necessary or desirable in  connection  with the
         acquisition  of the Target  Company and all  transactions  contemplated
         thereby;

                  (p) the Administrative  Agent has received a certificate dated
         on  or   immediately   prior  to  the  date  of  Permitted   Refractive
         Acquisition,  executed by the President or a Vice President of Borrower
         confirming  that all  representations  and  warranties set forth in the
         Loan Documents continue to be true and correct in all material respects
         immediately   prior  to  and  after  giving  effect  to  the  Permitted
         Refractive  Acquisition and the transactions  contemplated thereby, and
         setting  forth  the   calculations   supporting   compliance  with  the
         limitations prescribed herein; and

                  (q) Borrower or one of its Subsidiaries  must own at least 51%
         of the equity or membership interests in and Control the Target Company
         upon completion of the Permitted Refractive Acquisition.

         "Person"   means   any   individual,   corporation,   business   trust,
association,  company,  partnership,  joint venture,  Governmental Authority, or
other entity.

<PAGE>

         "Plan"  means  any  employee  benefit  or  other  plan  established  or
maintained  by Borrower or any ERISA  Affiliate of Borrower and which is covered
by Title IV of ERISA.

         "Pledge  Agreements" means (a) the Pledge Agreements,  each dated as of
April 26, 1996,  executed by Borrower and each Subsidiary of Borrower that owned
general and/or limited partnership interests in the Partnerships in favor of the
Administrative  Agent,  for the  benefit  of the  Lenders,  as the  same  may be
amended,  supplemented or modified from time to time, including (b) the Consent,
Confirmation  and  Ratification of Pledge and Security  Agreements,  dated as of
March 31, 1997, (c) the Second Consent,  Confirmation and Ratification of Pledge
and Security Agreements dated as April 20, 1998, and (d) the Pledge and Security
Agreements dated as of the date hereof,  and shall also include any other pledge
agreement  heretofore or hereafter  from time to time executed by any Person and
delivered  to  Administrative  Agent for the  benefit of  Lenders,  as  amended,
restated,  renewed,  and substituted from time to time. "Pledge Agreement" means
any one of the Pledge Agreements.

         "Pledgors"  means each of the  pledgors  of  partnership  interests  or
Assigned Rights (as defined in the applicable  Pledge  Agreement)  pursuant to a
Pledge Agreement. "Pledgor" means any one of the Pledgors.

     "PMOI" means Prime Medical Operating, Inc., a Delaware corporation, and its
permitted successors and assigns.

     "Prime  RVC"  means  Prime  RVC,  Inc.,  a  Delaware  corporation,  and its
permitted successors and assigns.

         "Principal  Office"  means  the  office  of the  Administrative  Agent,
presently located at 901 Main Street, 7th Floor, Dallas, Texas 75202.

     "Prohibited  Transaction" means any transaction set forth in Section 406 of
ERISA or Section 4975 of the Code.

         "Regulation  D" means  Regulation  D of the Board of  Governors  of the
Federal Reserve System as the same may be amended or  supplemented  from time to
time.

         "Regulatory Change" means, with respect to any Lender, any change after
the date of this Agreement in United States  federal,  state, or foreign laws or
regulations  (including  Regulation D) or the adoption or making after such date
of any  interpretations,  directives,  or requests  applying to a class of banks
including such Lender of or under any United States  federal,  state, or foreign
laws or  regulations  (whether  or not  having the force of law) by any court or
governmental  or  monetary   authority   charged  with  the   interpretation  or
administration thereof.

         "Release"  means,  as to any  Person,  any  release,  spill,  emission,
leaking,  pumping,  injection,  deposit,  disposal,  disbursement,  leaching, or
migration of Hazardous  Materials into the indoor or outdoor environment or into
or out of property  owned by such Person,  including,  without  limitation,  the
movement of Hazardous  Materials  through or in the air,  soil,  surface  water,
ground water, or property.

<PAGE>

         "Remedial  Action" means all actions  required to (a) clean up, remove,
treat,  or  otherwise  address  Hazardous  Materials  in the  indoor or  outdoor
environment,  (b)  prevent  the  Release or threat of Release  or  minimize  the
further  Release of Hazardous  Materials so that they do not migrate or endanger
or  threaten  to  endanger  public  health or  welfare  or the indoor or outdoor
environment,   or  (c)  perform  pre-remedial  studies  and  investigations  and
post-remedial monitoring and care.

         "Reportable Event" means any of the events set forth in Section 4043 of
ERISA.

         "Required  Lenders"  means,  as of any date, any combination of Lenders
(other than any Defaulting Lenders) who collectively hold sixty percent (60%) of
the sum of the  Commitments  (other than of any Defaulting  Lenders),  or if the
Commitments  shall have been terminated,  then of the aggregate unpaid principal
amount of the Notes (other than of any Defaulting Lenders).

         "Reserve  Requirement"  means,  for  any  Eurodollar  Advance  for  any
Interest  Period  therefor,  the average rate at which  reserves  (including any
marginal,  supplemental  or emergency  reserves)  are required to be  maintained
during such Interest Period under  Regulation D by each Lender on its portion of
such  Advance  against  "Eurocurrency  Liabilities"  as  such  term  is  used in
Regulation  D.  Without  limiting  the  effect  of the  foregoing,  the  Reserve
Requirement  shall  reflect any other  reserves  required to be  maintained by a
Lender  by  reason  of  any  Regulatory  Change  against  (i)  any  category  of
liabilities   which  includes  deposits  by  reference  to  which  the  Adjusted
Eurodollar  Rate is to be  determined,  or (ii) any  category of  extensions  of
credit or other assets which include Eurodollar Advances.

         "RICO" means the Racketeer  Influenced and Corrupt  Organization Act of
1970, as amended from time to time.

         "Senior Net Debt" means,  as of any date,  all Net Total Funded Debt of
the Companies which is not Subordinated Debt.

         "Senior Net Funded Debt to EBITDA  Ratio"  means,  as of any date,  the
ratio of (a) the aggregate  amount of Senior Net Debt of the Companies  (without
deduction for any minority  interests),  as of such date, to (b) Adjusted EBITDA
of the  Companies,  for the four (4) fiscal quarter period ending on the date of
determination  (including  on a  pro  forma  basis  any  Permitted  Acquisition,
Permitted Other Business Acquisition or Permitted Refractive Acquisition).

         "Senior  Subordinated  Indenture"  means that certain  Trust  Indenture
dated as of March 24,  1998  between  Borrower  and State  Street Bank and Trust
Company, as Trustee, and any trust indenture entered into in connection with the
Exchange Notes.

         "Senior Subordinated Notes" means those certain $100,000,000  aggregate
principal amount Senior  Subordinated  Notes issued by Borrower  pursuant to the
Senior  Subordinated  Indenture,  due April 1, 2008, and the Exchange  Notes, if
issued.

         "Solvent"  means,  with  respect  to any  Person,  that on the  date of
determination  (a) the fair market value of its assets is greater than the total
amount of liabilities,  including, without limitation, contingent liabilities of
such Person which would be required to be included on the balance  sheet of such
Person or disclosed in the  financial  statements  of such Person in  accordance
with GAAP,  (b) the present fair  salable  value of the assets of such Person is
not less than the amount that will be required to pay the probable  liability of
such Person on its debts as they become  absolute and  matured,  (c) such Person
does not intend to, and does  believe that it will,  incur debts or  liabilities
beyond such Person's  ability to pay as such debts and liabilities  mature,  and
(d) such Person is not engaged in business or transactions,  and is not about to
engage in business or  transactions,  for which its assets would  constitute  an
unreasonably small capital.

<PAGE>

         "Subordinated Debt" means the Senior Subordinated Notes.

         "Subsidiary"  means,  with  respect  to any  Person,  any  corporation,
partnership,  association,  or other business entity (a) of which  securities or
other  ownership  interests  representing  more than fifty  percent (50%) of the
equity or more than fifty  percent  (50%) of the  ordinary  voting power or more
than fifty  percent  (50%) of the general  partnership  interests or  membership
interests are, at the time any determination is made, owned,  Controlled or held
by such Person, or (b) that is, at the time any determination is made, otherwise
Controlled by one or more  Subsidiaries of such Person or by such Person and one
or more Subsidiaries of such Person.

         "Target  Company"  means any  Person  that has been or may be  acquired
pursuant to an Acquisition permitted hereunder.

         "Termination  Date"  means  1:00 p.m.  Dallas,  Texas time on April 21,
2003,  or such  earlier  date and time on which  the  Commitments  terminate  as
provided in this Agreement.

         "Total  Equity"  means,  at  any  particular  time,  the  sum  of:  (a)
Consolidated  Net Worth,  plus (b) outstanding  principal amount of Subordinated
Debt.

         "Total Net Funded  Debt to EBITDA  Ratio"  means,  as of any date,  the
ratio of (a) the  aggregate  outstanding  amount  of Net  Funded  Debt  (without
deduction for any minority  interests),  as of such date, to (b) Adjusted EBITDA
of the  Companies for the four (4) fiscal  quarter  period ending on the date of
determination  (including  on a pro forma basis any Permitted  Acquisition,  any
Permitted Other Business Acquisition, or Permitted Refractive Acquisition).

     "Type"  means any type of Advance  (i.e.,  Alternate  Base Rate  Advance or
Eurodollar Advance).

         "UCC"  means the Uniform  Commercial  Code as in effect in the State of
Texas or other applicable jurisdiction, as amended.

         "Wholly-Owned  Subsidiaries"  means,  as of any date, all  Subsidiaries
that are  wholly-owned  by Borrower or a  wholly-owned  Subsidiary  of Borrower.
"Wholly-Owned Subsidiary" means any one of the Wholly-Owned Subsidiaries.

         Section 1.3 Other Definitional Provisions. All definitions contained in
this  Agreement  are equally  applicable to the singular and plural forms of the
terms  defined.  The words  "hereof,"  "herein,"  and  "hereunder"  and words of
similar import  referring to this  Agreement  refer to this Agreement as a whole
and  not to  any  particular  provision  of  this  Agreement.  Unless  otherwise
specified, all Article, Section, Exhibit and Schedule references pertain to this
Agreement.  All  accounting  terms  not  specifically  defined  herein  shall be
construed  in  accordance  with  GAAP.  All  financial   covenants  and  related
definitions  relating to the Companies  shall,  unless otherwise  indicated,  be
determined  after  deduction  of  any  minority  interests,  provided  that  all
references to "Debt" shall  include all Debt without  deduction for any minority
interests.  Terms used  herein  that are  defined in the UCC,  unless  otherwise
defined herein, shall have the meanings specified in the UCC.

<PAGE>

                             ARTICLE II -- ADVANCES

         Section 2.1       Commitments.

         (a) Revolving Credit  Commitments.  Subject to the terms and conditions
of this  Agreement,  each  Lender  hereby  severally  agrees to make one or more
Advances to Borrower  from time to time from the date hereof to the  Termination
Date in an  aggregate  principal  amount at any time  outstanding  up to but not
exceeding the amount of such Lender's  Commitment as then in effect.  Subject to
the foregoing limitations, and the other terms and provisions of this Agreement,
Borrower may borrow, repay, and reborrow hereunder the amount of the Commitments
by means of Eurodollar Advances or Alternate Base Rate Advances.

         (b) Optional  Reduction and Termination of Commitments.  Borrower shall
have the right to terminate in whole or reduce in part the unused portion of the
Commitments  upon at least three (3) Business  Days' prior written notice (which
notice  shall  be  irrevocable)  to  the  Administrative  Agent  specifying  the
effective  date thereof,  whether a termination  or reduction is being made, and
the amount of any partial reduction,  provided that each partial reduction shall
be in the amount of  $1,000,000.00  or a greater  integral  multiple thereof and
Borrower shall  simultaneously  prepay the amount by which the unpaid  principal
amount of the Notes exceeds the Commitments (after giving effect to such notice)
plus accrued and unpaid interest on the principal amount so prepaid.  No portion
of the Commitments may be reinstated after it has been terminated or reduced.

         Section 2.2 Notes.  The obligation of Borrower to repay each Lender for
Advances  made by such Lender  pursuant  to such  Lender's  Commitment,  and all
interest thereon,  shall be evidenced by a Note dated the date hereof,  executed
by Borrower  and payable to the order of such Lender in the  original  principal
amount of such Lender's  Commitment.  Upon receipt of an affidavit of an officer
of any Lender to the loss, theft, destruction or mutilation of any Note, and, in
the case of any such loss, theft,  destruction or mutilation,  upon cancellation
of such Note,  Borrower will issue, in lieu thereof,  a replacement  note in the
same principal amount thereof and otherwise of like tenor.

     Section 2.3  Repayment of Advances.  Borrower  shall repay the  outstanding
principal amount of the Notes on the Termination Date.

         Section 2.4 Interest. The unpaid principal amount of all Advances shall
bear interest at a varying rate per annum equal from day to day to the lesser of
(a) the Maximum Rate, or (b) the Applicable  Rate. If at any time the Applicable
Rate for any Advance shall exceed the Maximum Rate, thereby causing the interest
accruing on such Advance to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate for such Advance shall not reduce the rate of
interest on such Advance  below the Maximum Rate until the  aggregate  amount of
interest  accrued on such Advance equals the aggregate  amount of interest which
would have accrued on such Advance if the Applicable  Rate had at all times been
in effect.  Accrued and unpaid interest on the Advances shall be due and payable
on each Payment Date and on the Termination Date. Notwithstanding the foregoing,
any outstanding principal of any Advance and (to the fullest extent permitted by
law) any other amount payable by Borrower under this Agreement or any other Loan
Document  that is not paid in full  when due  (whether  at stated  maturity,  by
acceleration,  or  otherwise)  shall bear  interest at the Default  Rate for the
period from and  including  the due date thereof to but  excluding  the date the
same is paid in full. Interest payable at the Default Rate shall be payable from
time to time on demand.

<PAGE>

         Section 2.5       Borrowing Procedure.

         (a) Loan. Borrower shall give the Administrative  Agent notice by means
of an Advance  Request  Form of each  requested  Advance  under the  Commitments
hereunder at least three (3)  Business  Days before the  requested  date of each
Eurodollar  Advance (and at least one (1) Business Day before the requested date
of each Alternate Base Rate Advance), specifying: (a) the requested date of such
Advance (which shall be a Business Day); (b) the amount of such Advance; and (c)
the duration of the Interest Period for such Advance (if a Eurodollar  Advance).
The  Administrative  Agent at its  option  may accept  telephonic  requests  for
Advances  under  the  Commitments,  provided  that  such  acceptance  shall  not
constitute  a waiver  of the  Administrative  Agent's  right to  delivery  of an
Advance  Request  Form  in  connection   with  subsequent   Advances  under  the
Commitments.  Any  telephonic  request for an Advance under the  Commitments  by
Borrower  shall be promptly  confirmed  by  submission  of a properly  completed
Advance  Request  Form to the  Administrative  Agent.  Each  Advance  under  the
Commitments shall be in a minimum principal amount of $1,000,000.00 or a greater
integral  multiple  thereof,  provided  that if such  Advance  equals the entire
remaining  unfunded  portion of the Commitments,  it may be for any amount.  The
aggregate  principal  amount of  Eurodollar  Advances  having the same  Interest
Period shall be at least equal to $2,500,000.00  or a greater integral  multiple
of  $500,000.00.  All notices under this Section 2.5(a) shall be irrevocable and
shall be given not later than 11:00 a.m. Dallas,  Texas time on the day which is
not less than the number of Business Days specified above for such notice.

         (b) Generally.  The  Administrative  Agent shall  promptly  notify each
Lender of the contents of each Advance  Request Form.  Not later than 11:00 a.m.
Dallas, Texas time on the date specified for each Advance hereunder, each Lender
will make  available  to the  Administrative  Agent at the  Principal  Office in
immediately available funds, for the account of Borrower,  its pro rata share of
each Advance. After the Administrative Agent's receipt of such funds and subject
to the other terms and conditions of this Agreement,  the  Administrative  Agent
will  make each  Advance  available  to  Borrower  by  depositing  the same,  in
immediately  available funds, in a deposit account of Borrower maintained at the
Documentation Agent.

         Section 2.6       Continuations; Conversions.

         (a) Continuations. Borrower shall have the right to Continue Eurodollar
Advances by giving the Administrative  Agent written notice specifying:  (i) the
Continuation date; (ii) the amount of the Advance to be Continued; and (iii) the
duration of the  Interest  Period  applicable  thereto,  which  notice  shall be
irrevocable  and must be given by  Borrower  not later than  11:00 a.m.  Dallas,
Texas time at least three (3) Business Days before each such  Continuation.  The
Administrative  Agent shall promptly  notify each Lender of the contents of each
such notice. If Borrower shall fail to give the Administrative  Agent the notice
as specified above for Continuation of a Eurodollar  Advance prior to the end of
the  Interest  Period  applicable  thereto,  such  Eurodollar  Advance  shall be
automatically Continued for a one (1) month Interest Period.

         (b) Conversions.  Borrower shall have the right to Convert an Alternate
Base  Rate  Advance  at  any  time  to  a  Eurodollar   Advance  by  giving  the
Administrative  Agent written notice  specifying:  (i) the Conversion Date; (ii)
the  amount of the  Advance  to be  Converted;  and (iii)  the  duration  of the
Interest Period applicable  thereto,  which notice shall be irrevocable and must
be given by Borrower not later than 11:00 a.m. Dallas, Texas time at least three
(3) Business Days before each such Conversion.  The  Administrative  Agent shall
promptly notify each Lender of the contents of each such notice.

     (c) Default.  After the occurrence and during the continuance of a Default,
no  outstanding  Advances may be Converted  into,  or Continued as, a Eurodollar
Advance.

<PAGE>

         Section  2.7 Use of  Proceeds.  The  proceeds  of  Advances  under  the
Commitments  shall  be  used  by  Borrower  (i)  for  working  capital,  capital
expenditures,  and other lawful corporate  purposes,  (ii) to finance  Permitted
Acquisitions,   Permitted  Other  Business   Acquisitions,   Permitted   Passive
Investments,  and  Permitted  Refractive  Acquisitions,   (iii)  to  the  extent
permitted  by  this  Agreement,  to  repurchase  outstanding  capital  stock  of
Borrower,  (iv) to make loans or capital contributions to its Subsidiaries,  the
proceeds  of  which  are  used by each  such  Subsidiary  for one or more of the
purposes  permitted by subsections (i), (ii), and (iii) of this Section 2.7, and
(v) to finance advances by PMOI or another Guarantor to LASIK Investors,  L.L.C.
for the  acquisition  of  certain  interests  in  certain  Permitted  Refractive
Acquisitions.

         Section 2.8       Fees.

         (a)   Commitment   Fees.   Borrower   hereby   agrees  to  pay  to  the
Administrative   Agent,  for  the  ratable  account  of  each  Lender  having  a
Commitment, a commitment fee on the daily average unused amount of such Lender's
Commitment  for the period from and including the date of this  Agreement to but
excluding the  Termination  Date, at the per annum rate equal to the  Applicable
Unused  Fee  Percentage  based on a 360-day  year,  as the case may be,  and the
actual  number of days  elapsed.  Accrued  commitment  fees  shall be payable in
arrears on each Payment Date and on the Termination Date.

     (b) Agents' Fees. Borrower hereby agrees to pay to the Agents for their own
respective accounts, the fees agreed to by Borrower and the Agents pursuant to a
side letter agreement with each Agent.

                             ARTICLE III -- PAYMENTS

         Section 3.1 Method of Payment. All payments of principal, interest, and
other  amounts to be paid by Borrower  under this  Agreement  and the other Loan
Documents shall be paid to the Administrative  Agent at the Principal Office for
the  account  of each  Lender's  Applicable  Lending  Office in  Dollars  and in
immediately  available funds, without setoff,  deduction,  or counterclaim,  not
later than 1:00 p.m. Dallas,  Texas time on the date on which such payment shall
become due (each such payment made after such time on such due date to be deemed
to have been made on the next succeeding  Business Day).  Borrower shall, at the
time of making each such payment,  specify to the Administrative  Agent the sums
payable by Borrower  under this  Agreement and the other Loan Documents to which
such  payment  is to be  applied  (and in the event  that  Borrower  fails to so
specify,  or if an  Event  of  Default  has  occurred  and  is  continuing,  the
Administrative Agent may apply such payment to the Obligations in such order and
manner as it may elect in its sole  discretion,  subject to Section  3.4).  Each
payment received by the  Administrative  Agent under this Agreement or any other
Loan Document for the account of a Lender shall be paid promptly to such Lender,
in  immediately  available  funds,  for the account of such Lender's  Applicable
Lending  Office.  Whenever  any payment  under this  Agreement or any other Loan
Document  shall be stated to be due on a day that is not a  Business  Day,  such
payment may be made on the next  succeeding  Business Day, and such extension of
time  shall in such  case be  included  in the  computation  of the  payment  of
interest and commitment fee, as the case may be.

<PAGE>

         Section 3.2 Optional Prepayment.  Borrower may, upon at least three (3)
Business  Days' prior notice to the  Administrative  Agent,  prepay the Notes in
whole or in part at any time or from time to time without premium or penalty but
with  accrued  interest  to the date of  prepayment  on the  amount so  prepaid,
provided that (a) Eurodollar  Advances  prepaid on a day other than the last day
of  the  Interest   Period  for  such  Advances  shall  include  the  additional
compensation,  if any, required by Section 4.5, and (b) each partial  prepayment
shall be in the amount of the aggregate remaining  outstanding  principal amount
of the  Eurodollar  Advances or in the principal  amount of  $1,000,000.00  or a
greater integral multiple  thereof.  All notices under this Section 3.2 shall be
irrevocable  and must be given by  Borrower  not later than  11:00 a.m.  Dallas,
Texas  time on the day  which  is not less  than the  number  of  Business  Days
specified above for such notice.  Optional  prepayments  shall be applied as set
forth in Section  3.9.  Optional  prepayments  shall not reduce the  Commitments
unless Borrower so elects pursuant to Section 2.1(b).

         Section 3.3       Mandatory Prepayments.

                  (a) Asset Sales.  Immediately upon the receipt of the proceeds
         thereof,  Borrower shall prepay the Notes in an amount equal to the net
         proceeds of any sale,  liquidation  or disposition of any assets of any
         Company   (other   than  the   Partnerships   or  the   assets  of  the
         Partnerships), where such net proceeds exceed $100,000.00.

               (b) Sale or Issuance of Capital Stock or Debt.  Immediately  upon
          the receipt of the proceeds  thereof,  Borrower shall prepay the Notes
          in an amount equal to 100 percent (100%) of any Issuance Proceeds.

                  (c) Application of Mandatory  Prepayments.  Any such mandatory
         prepayments  of the Notes  shall be  applied to the Notes on a pro rata
         basis based upon the outstanding principal balances of such Notes as of
         the  date of  payment.  Any  such  prepayments  shall  not  reduce  the
         Commitments.

         Section 3.4 Pro Rata Treatment. Except to the extent otherwise provided
herein:  (a) the making and  Continuation of Advances under the Commitment shall
be made pro rata among the Lenders  according to the amounts of their respective
Commitments;  (b) each termination or reduction of the Commitments under Section
2.1(b) or otherwise shall be applied to the Commitments of the Lenders pro rata,
according  to their  respective  unused  Commitments;  and (c) each  payment and
prepayment of principal of or interest on Advances by Borrower  shall be made to
the Administrative Agent for the account of the applicable Lenders in accordance
with Section 3.9.

         Section 3.5 Non-Receipt of Funds by the  Administrative  Agent.  Unless
the  Administrative  Agent shall have been notified by a Lender or Borrower (the
"Payor")  prior to the date on  which  such  Lender  is to make  payment  to the
Administrative Agent of the proceeds of an Advance to be made by it hereunder or
Borrower is to make a payment to the Administrative Agent for the account of one
or more of the Lenders, as the case may be (such payment being herein called the
"Required  Payment"),  which notice shall be effective  upon  receipt,  that the
Payor does not intend to make the Required Payment to the Administrative  Agent,
the Administrative  Agent may assume that the Required Payment has been made and
may, in reliance upon such  assumption  (but shall not be required to), make the
amount  thereof  available  to the  intended  recipient on such date and, if the
Payor has not in fact made the Required Payment to the Administrative Agent, the
recipient of such payment shall, on demand,  return to the Administrative  Agent
the amount made available to it together with interest thereon in respect of the
period  commencing  on the  date  such  amount  was  so  made  available  by the
Administrative  Agent  until the date the  Administrative  Agent  recovers  such
amount at a rate per annum equal to the Federal Funds Rate for such period.

<PAGE>

         Section 3.6 Withholding Taxes. All payments by Borrower of principal of
and interest on the Advances and of all fees and other amounts payable under any
Loan Document are payable without  deduction for or on account of any present or
future taxes,  duties or other charges levied or imposed by the United States of
America or by the  government of any  jurisdiction  outside the United States of
America or by any political  subdivision or taxing authority of or in any of the
foregoing through withholding or deduction with respect to any such payments. If
any such taxes, duties or other charges are so levied or imposed,  Borrower will
pay additional interest or will make additional payments in such amounts so that
every net payment of  principal of and interest on the Advances and of all other
amounts  payable by any of them under any Loan  Document,  after  withholding or
deduction for or on account of any such present or future taxes, duties or other
charges,  will not be less than the  amount  provided  for  herein  or  therein,
provided that Borrower shall have no obligation to pay such  additional  amounts
to any Lender to the extent that such taxes, duties, or other charges are levied
or imposed by reason of the failure of such Lender to comply with the provisions
of Section 3.7. Borrower shall furnish promptly to the Administrative  Agent for
distribution  to each affected  Lender,  as the case may be,  official  receipts
evidencing any such withholding or reduction.

         Section  3.7  Withholding  Tax  Exemption.  Each  Lender  that  is  not
incorporated  under the laws of the United  States of America or a state thereof
agrees that it will  deliver to Borrower  and the  Administrative  Agent two (2)
duly completed  copies of United States  Internal  Revenue  Service Form 1001 or
4224, certifying in either case that such Lender is entitled to receive payments
from Borrower under any Loan Document,  without  deduction or withholding of any
United States federal  income taxes or (b) if such Lender is claiming  exemption
from United States  withholding  tax under Section  871(h) or 881(c) of the Code
with respect to payments of  "portfolio  interest," a Form W-8, or any successor
form prescribed by the Internal Revenue Service, and a certificate  representing
that such Lender is not a bank for  purposes of Section  881(c) of the Code,  is
not a 10-percent  shareholder (within the meaning of Section 871(h)(3)(B) of the
Code) of the Borrower and is not a controlled foreign corporation related to the
Borrower  (within the  meaning of Section  864(d)(4)  of the Code).  Each Lender
which so  delivers a W-8,  Form 1001 or 4224  further  undertakes  to deliver to
Borrower and the Administrative Agent two (2) additional copies of such form (or
a successor form) on or before the date such form expires or becomes obsolete or
after the occurrence of any event  requiring a change in the most recent form so
delivered by it, and such amendments  thereto or extensions or renewals  thereof
as may be reasonably requested by Borrower or the Administrative  Agent, in each
case certifying  that such Lender is entitled to receive  payments from Borrower
under any Loan Document  without  deduction or  withholding of any United States
federal income taxes,  unless an event (including  without limitation any change
in treaty,  law or regulation)  has occurred prior to the date on which any such
delivery would  otherwise be required which renders all such forms  inapplicable
or which would prevent such Lender from duly  completing and delivering any such
form with respect to it and such Lender advises Borrower and the  Administrative
Agent that it is not capable of receiving such payments without any deduction or
withholding of United States federal income tax.

         Section 3.8  Computation of Interest.  Interest on all Advances and all
other amounts payable by Borrower  hereunder shall be computed on the basis of a
year of 360 days, and actual days elapsed.

         Section 3.9       Order of Application.

         (a) No  Default.  Prior to the  occurrence  of an Event of Default  any
payment  (whether  voluntary or  mandatory) of the Notes shall be applied to the
Notes on a pro rata basis based upon the outstanding  principal  balances of the
Notes as of the date of payment.

<PAGE>

         (b) After Default.  After the occurrence and during the  continuance of
an Event of Default,  any payment or proceeds of Collateral  shall be applied in
the  following  order:  (i) to all fees and expenses for which Agents or Lenders
have not been paid or reimbursed in accordance  with the Loan  Documents (and if
such payment is less than all unpaid or unreimbursed fees and expenses, then the
payment shall be paid against unpaid and  unreimbursed  fees and expenses in the
order of incurrence or due date); (ii) to accrued interest on the Notes on a pro
rata basis, based upon the outstanding principal balances of the Notes as of the
date of payment;  (iii) to the  principal of the Notes and amounts due and owing
under  any  Financial  Hedge on a pro rata  basis,  based  upon the  outstanding
principal  balances of the Notes or obligation due and owing under any Financial
Hedge as of the date of payment; and (iv) to all other Obligations.

         (c) Application to Advances.  Subject to the foregoing,  and so long as
no Event of Default has occurred and is continuing, payments of principal of any
Note shall be applied  to such  outstanding  Alternate  Base Rate  Advances  and
Eurodollar Advances under such Note as Borrower shall select; provided, however,
that Borrower shall select Alternate Base Rate Advances and Eurodollar  Advances
to be repaid in a manner  designated to minimize the funding loss required to be
paid pursuant to Section 4.5, if any, resulting from such payment;  and provided
further that if Borrower  shall fail to select the Alternate  Base Rate Advances
and Eurodollar Advances to which such payments are to be applied, or if an Event
of Default has occurred and is continuing at the time of such payment,  then the
Administrative  Agent shall be entitled to apply the payment to such Advances in
the manner in which it shall deem appropriate in its sole discretion.

                  ARTICLE IV -- YIELD PROTECTION AND ILLEGALITY

         Section 4.1       Additional Costs.

         (a) Borrower  hereby agrees to pay directly to each Lender from time to
time such amounts as such Lender may  determine to be necessary to compensate it
for  any  costs  incurred  by such  Lender  which  such  Lender  determines  are
attributable to its making or maintaining any Eurodollar  Advances  hereunder or
its obligation to make any of such Advances  hereunder,  or any reduction in any
amount  receivable  by such Lender  hereunder in respect of any such Advances or
such obligation  (such  increases in costs and reductions in amounts  receivable
being herein called  "Additional  Costs"),  resulting from any Regulatory Change
which:

                  (i) changes  the basis of  taxation of any amounts  payable to
         such Lender under this Agreement or its Notes in respect of any of such
         Advances  (other  than (1) taxes  imposed on the  overall net income of
         such Lender or its Applicable  Lending Office for any of such Advances,
         (2) franchise or similar taxes of such Lender, and (3) amounts withheld
         pursuant to the last sentence of Section 3.7);

                  (ii) imposes or modifies any reserve, special deposit, minimum
         capital,   capital  ratio,  or  similar  requirement  relating  to  any
         extensions  of credit or other assets of, or any deposits with or other
         liabilities or commitments of, such Lender; or

                  (iii)  imposes  any  other   Additional  Cost  affecting  this
         Agreement  or the  Notes  or any  of  such  extensions,  of  credit  or
         liabilities or commitments.

<PAGE>

Each Lender will notify  Borrower of any event  occurring after the date of this
Agreement  which will  entitle  such  Lender to  compensation  pursuant  to this
Section 4.1(a) as promptly as practicable after it obtains knowledge thereof and
determines  to  request  such  compensation,  and  will  designate  a  different
Applicable  Lending  Office  for the  Advances  affected  by such  event if such
designation will avoid the need for, or reduce the amount of, such  compensation
and will not, in the sole  opinion of such  Lender,  violate any law,  rule,  or
regulation or be in any way  disadvantageous to such Lender,  provided that such
Lender shall have no  obligation to so designate an  Applicable  Lending  Office
located outside the United States of America.  Each Lender will furnish Borrower
with a  certificate  setting  forth the basis and the amount of each  request of
such Lender for compensation  under this Section 4.1(a).  If any Lender requests
compensation from Borrower under this Section 4.1(a), Borrower may, by notice to
such Lender (with a copy to the Administrative  Agent) suspend the obligation of
such Lender to make or Continue making Eurodollar  Advances until the Regulatory
Change  giving rise to such  request  ceases to be in effect (in which case such
Lender's  Eurodollar Advances shall be Converted to Alternate Base Rate Advances
in accordance with the provisions of Section 4.4).

         (b) Without  limiting the effect of the  foregoing  provisions  of this
Section 4.1, in the event that, by reason of any Regulatory  Change,  any Lender
either (i) incurs  Additional  Costs based on or measured by the excess  above a
specified level of the amount of a category of deposits or other  liabilities of
such Lender which  includes  deposits by reference to which the interest rate on
Eurodollar Advances is determined as provided in this Agreement or a category of
extensions  of credit or other assets of such Lender which  includes  Eurodollar
Advances  or (ii)  becomes  subject  to  restrictions  on the  amount  of such a
category of  liabilities  or assets which it may hold,  then,  if such Lender so
elects by notice to  Borrower  (with a copy to the  Administrative  Agent),  the
obligation  of such  Lender  to  make or  Continue  making  Eurodollar  Advances
hereunder shall be suspended until such Regulatory Change ceases to be in effect
(in which case such Lender's Eurodollar Advances shall be Converted to Alternate
Base Rate Advances in accordance with the provisions of Section 4.4).

         (c)  Determinations  and allocations by any Lender for purposes of this
Section 4.1 of the effect of any  Regulatory  Change on its costs of maintaining
its  obligations  to make  Advances or of making or  maintaining  Advances or on
amounts  receivable by it in respect of Advances,  and of the additional amounts
required to compensate such Lender in respect of any Additional Costs,  shall be
conclusive,  absent  manifest  error and provided that such  determinations  and
allocations are made on a reasonable basis.

     Section 4.2  Limitation  on  Eurodollar  Advances.  Anything  herein to the
contrary  notwithstanding,  if with  respect to any  Eurodollar  Advance for any
Interest Period therefor:

         (a) The Administrative  Agent determines (which  determination shall be
conclusive  absent  manifest  error) that  quotations of interest  rates for the
relevant  deposits referred to in the definition of "Eurodollar Rate" in Section
1.1  are  not  being  provided  in the  relative  amounts  or for  the  relative
maturities for purposes of determining the rate of interest for such Advances as
provided in this Agreement; or

         (b) The  Required  Lenders  determine  (which  determination  shall  be
conclusive absent manifest error) and notify the  Administrative  Agent that the
rate of interest  referred to in the definition of "Eurodollar  Rate" in Section
1.1 on the  basis  of which  the rate of  interest  for such  Advances  for such
Interest  Period is to be determined do not  accurately  reflect the cost to the
Lenders of making or maintaining such Advances for such Interest Period;

then  the  Administrative  Agent  shall  give  Borrower  prompt  notice  thereof
specifying  the  relevant  amounts  or  periods,  and so long as such  condition
remains in effect,  the Lenders shall be under no obligation to make or Continue
additional  Eurodollar  Advances and Borrower  shall,  on the last day(s) of the
then-current Interest Period(s) for the outstanding Eurodollar Advances,  prepay
such  Eurodollar  Advances or Convert  them to Alternate  Base Rate  Advances in
accordance with Section 4.4.

<PAGE>

         Section 4.3  Illegality.  Notwithstanding  any other  provision of this
Agreement,  in the  event  that  it  becomes  unlawful  for  any  Lender  or its
Applicable  Lending  Office  to (a)  honor  its  obligation  to make  Eurodollar
Advances hereunder,  or (b) maintain  Eurodollar  Advances hereunder,  then such
Lender shall promptly notify Borrower (with a copy to the Administrative  Agent)
thereof and such  Lender's  obligation to make or maintain  Eurodollar  Advances
shall be  suspended  until such time as such Lender may again make and  maintain
Eurodollar  Advances (in which case such Lender's  Eurodollar  Advances shall be
Converted to Alternate  Base Rate Advances in accordance  with the provisions of
Section 4.4).

         Section  4.4  Treatment  of  Eurodollar  Advances.  If  the  Eurodollar
Advances of any Lender are to be Converted  pursuant to Section 4.1, 4.2 or 4.3,
such  Lender's  Eurodollar  Advances  shall  be  automatically   Converted  into
Alternate  Base Rate  Advances on the last day(s) of the then  current  Interest
Period(s) for the Eurodollar  Advances (or, in the case of a Conversion required
by Section 4.1(b) or 4.3(b),  on such earlier date as such Lender may specify to
Borrower  with a copy to the  Administrative  Agent) and,  unless and until such
Lender  gives  notice as  provided  below that the  circumstances  specified  in
Section 4.1, 4.2 or 4.3 which gave rise to such Conversion no longer exist:

         (a) To the extent that such Lender's  Eurodollar  Advances have been so
Converted,  all payments and  prepayments of principal  which would otherwise be
applied to such Lender's  Eurodollar  Advances  shall be applied  instead to its
Alternate Base Rate Advances; and

         (b) All  Advances  which would  otherwise  be made or Continued by such
Lender as Eurodollar  Advances shall be made as or Converted into Alternate Base
Rate Advances.

If such  Lender  gives  notice to  Borrower  (with a copy to the  Administrative
Agent) that the circumstances specified in Section 4.1, 4.2 or Section 4.3 which
gave rise to the  Conversion of such Lender's  Eurodollar  Advances  pursuant to
this Section 4.4 no longer exist (which such Lender  agrees to do promptly  upon
such  circumstances  ceasing to exist) at a time when Advances are  outstanding,
such Lender's Alternate Base Rate Advances shall be automatically  Converted, on
the first day(s) of the next succeeding  Interest Period(s) for such outstanding
Eurodollar  Advances  to the  extent  necessary  so that,  after  giving  effect
thereto,  all Eurodollar  Advances held by the Lenders holding the same are held
pro rata (as to principal amounts and Interest Periods) in accordance with their
respective Commitments.

         Section  4.5  Compensation.  Borrower  shall pay to the  Administrative
Agent,  for the account of each Lender,  upon the request of such Lender through
the Administrative  Agent, such amount or amounts as shall be sufficient (in the
reasonable  opinion of such  Lender) to  compensate  it for any loss,  cost,  or
expense incurred by it as a result of:

         (a) Any payment,  prepayment or Conversion of a Eurodollar  Advance for
any reason (including,  without limitation,  the acceleration of the outstanding
Advances  pursuant  to  Section  11.2) on a date  other  than the last day of an
Interest Period for such Advance; or

         (b)  Any  failure  by  Borrower  for  any  reason  (including,  without
limitation,  the failure of any conditions  precedent specified in Article VI to
be  satisfied)  to borrow or prepay a  Eurodollar  Advance  on the date for such
borrowing  or  prepayment,  specified  in the  relevant  notice of  borrowing or
prepayment under this Agreement.

Such  compensation  shall not exceed the  excess,  if any,  of (i) the amount of
interest which otherwise  would have accrued on the principal  amount so paid or
not  borrowed  for the period from the date of such payment or failure to borrow
to the last day of the  Interest  Period for such  Advance (or, in the case of a
failure  to  borrow,  the  Interest  Period for such  Advance  which  would have
commenced on the date specified for such  borrowing) at the  applicable  rate of
interest for such Advance  provided for herein over (ii) the interest  component
of the amount  such  Lender  would have bid in the London  interbank  market for
Dollar deposits of leading banks and amounts comparable to such principal amount
and with maturities comparable to such period.

<PAGE>

         Section  4.6 Capital  Adequacy.  If after the date  hereof,  any Lender
shall have determined that the adoption or implementation of any applicable law,
rule, or regulation regarding capital adequacy  (including,  without limitation,
any law,  rule,  or regulation  implementing  the Basle  Accord),  or any change
therein,  or any change in the  interpretation or administration  thereof by any
central bank or other Governmental  Authority charged with the interpretation or
administration  thereof,  or  compliance by such Lender (or its parent) with any
guideline,  request,  or directive  regarding  capital adequacy  (whether or not
having the force of law) of any  central  bank or other  Governmental  Authority
(including,  without limitation, any guideline or other requirement implementing
the Basle  Accord),  has or would have the effect of reducing the rate of return
on such Lender's (or its parent's)  capital as a consequence of its  obligations
hereunder or the  transactions  contemplated  hereby to a level below that which
such  Lender  (or  its  parent)  could  have  achieved  but for  such  adoption,
implementation,  change or compliance  (taking into  consideration such Lender's
policies with respect to capital adequacy) by an amount deemed by such Lender to
be material,  then from time to time, within ten (10) Business Days after demand
by such Lender (with a copy to the Administrative  Agent), which demand shall be
delivered  by such Lender to Borrower  as  promptly  as  practicable  after such
Lender obtains knowledge of such reduction in its rate of return, Borrower shall
pay to such Lender such  additional  amount or amounts as will  compensate  such
Lender (or its parent) for such reduction. A certificate of such Lender claiming
compensation  under this  Section and  setting  forth the  additional  amount or
amounts to be paid to it hereunder  shall be conclusive,  absent  manifest error
and provided that the  determination  thereof is made on a reasonable  basis. In
determining such amount or amounts, such Lender may use any reasonable averaging
and attribution methods.

                              ARTICLE V -- SECURITY

         Section 5.1  Collateral.  To secure the full and  complete  payment and
performance of the  Obligations,  Borrower shall execute and deliver or cause to
be executed and delivered the documents  described  below  covering the property
and collateral  described  therein (which,  together with any other property and
collateral  which  may now or  hereafter  secure  the  Obligations  or any  part
thereof, is sometimes herein called the "Collateral"):

     (a) Borrower Security Agreement.  Borrower shall execute and deliver to the
Administrative Agent, for the benefit of the Lenders, the Consent,  Confirmation
and Ratification of the Borrower Security Agreement.

         (b) Guarantor Security Agreement. The existing Guarantors shall execute
and deliver to the  Administrative  Agent,  for the benefit of the Lenders,  the
Consent, Confirmation and Ratification of the Guarantor Security Agreements, and
Prime RVC shall execute and deliver to the Administrative Agent, for the benefit
of the Lenders, a Guarantor Security Agreement.

     (c)  Pledge   Agreement.   Pledgors   shall  execute  and  deliver  to  the
Administrative Agent, for the benefit of the Lenders, the Consent,  Confirmation
and Ratification of the Pledge Agreements.

         (d) Further Assurances. Borrower shall execute and cause to be executed
such further documents and instruments,  including without  limitation,  Uniform
Commercial  Code  financing  statements,  as the  Administrative  Agent  and the
Documentation  Agent, in their sole  discretion,  deem necessary or desirable to
evidence and perfect the Administrative  Agent's liens and security interests in
the Collateral.

<PAGE>

     (e) Description of Collateral. Collateral includes, without limitation, the
following assets of Borrower and Guarantors:

                  (i) All present and future accounts,  contract rights, general
         intangibles,  chattel paper,  documents,  instruments,  notes and other
         debt instruments,  and any collateral therefor,  inventory,  equipment,
         and other goods, wherever located, now owned or hereafter acquired.

                  (ii) All present and future issued and  outstanding  shares of
         capital stock of, or partnership and membership interests, now owned or
         hereafter  acquired by Borrower or any  Guarantor,  including,  without
         limitation,  all  capital  stock  of,  or  partnership  and  membership
         interests in, the Guarantors.

                  (iii) To the  extent  allowed  by the  respective  partnership
         agreements,  certain  partnership  interests  or economic  interests in
         partnership interests owned by Borrower and Guarantors.

                  (iv)  All  present  and  future  automobiles,   trucks,  truck
         tractors, trailers,  semi-trailers,  or other motor vehicles or rolling
         stock now owned or  hereafter  acquired by  Borrower  or any  Guarantor
         (collectively, the "Vehicles").

                  (v) All present and future  rights,  awards,  and judgments to
         which  Borrower or any Guarantor is entitled  under any  litigation now
         existing or hereafter arising.

                  (vi) All present and future rights,  titles,  and interests of
         Borrower or any Guarantor in and to all patents,  patent  applications,
         patent right,  service marks,  trademarks,  tradenames,  trade secrets,
         intellectual property, registrations, goodwill, copyrights, franchises,
         licenses,  permits,  proprietary information,  customer lists, designs,
         and inventions.

                  (vii) All  present and future  books,  records,  data,  plans,
         manuals,  computer  software  and  computer  programs of  Borrower  and
         Guarantors.

               (viii) All  proceeds and  products of the  Collateral  heretofore
          described.

         Section 5.2 Future Liens.  Promptly, and in any event within twenty-one
(21) days after (a) the acquisition of any assets (real, personal,  tangible, or
intangible)  by Borrower or any  Guarantor or (b) the removal,  termination,  or
expiration  of any  prohibition  upon the granting of a lien in any asset (real,
personal,  tangible, or intangible) of any Borrower or any Guarantor (including,
without limitation, the granting of liens in all general and limited partnership
interests  in  which  Borrower  and  Guarantors  own  100%  of  the  partnership
interests) (the "Additional Assets"),  Borrower shall (or shall cause such other
Guarantor  to)  execute  and  deliver  to   Administrative   Agent  all  further
instruments  and documents  (including,  without  limitation,  certificates  and
instruments  representing  shares  of stock or  evidencing  Debt and any  realty
appraisals  as  Administrative  Agent  may  require  with  respect  to any  such
Additional Assets), and shall take all such further action that may be necessary
or desirable,  or that  Administrative  Agent may reasonably  request, to grant,
perfect,  and protect liens in favor of Administrative  Agent for the benefit of
Lenders in such Additional  Assets,  as security for the  Obligations;  it being
expressly  understood  that the  granting of such  additional  security  for the
Obligations  is a material  inducement  to the  execution  and  delivery of this
Agreement by each Lender.  Upon satisfying the terms and conditions hereof, such
Additional  Assets shall be included in the  "Collateral" for all purposes under
the Loan Documents, and all references to the "Collateral" in the Loan Documents
shall include the Additional Assets.

<PAGE>

         Section  5.3  Release  of  Collateral.  Upon  any  sale,  transfer,  or
disposition  of  Collateral  which is expressly  permitted  pursuant to the Loan
Documents  (or is otherwise  authorized by Required  Lenders or Lenders,  as the
case may be), and upon ten (10) Business Days' prior written request by Borrower
(which  request  must be  accompanied  by true  and  correct  copies  of (a) all
documents of transfer or  disposition,  including  any  contract of sale,  (b) a
preliminary closing statement and instructions to the title company, if any, and
(c) all requested release instruments, Administrative Agent shall (and is hereby
irrevocably  authorized  by the  Lenders to) execute  such  documents  as may be
necessary to evidence the release of liens granted to  Administrative  Agent for
the benefit of lenders pursuant hereto in such Collateral; provided that, (x) no
such  release of Lien shall be  granted if any  Default or Event of Default  has
occurred and is continuing,  including,  without limitation, the failure to make
certain  mandatory  prepayments in accordance with Section 3.3(a) in conjunction
with the sale and transfer of such Collateral;  (y)  Administrative  Agent shall
not be required to execute any such document on terms which,  in  Administrative
Agent's opinion,  would expose  Administrative  Agent to liability or create any
obligation  or entail  any  consequence,  other  than the  release of such Liens
without  recourse  or  warranty;  and (z) such  release  shall not in any manner
discharge,  affect,  or impair the Obligations,  or liens upon or obligations of
Borrower or any Guarantor in respect of all  interests  retained by the Borrower
and Guarantors,  including, without limitation, the proceeds of any sale, all of
which shall continue to constitute Collateral.

         Section 5.4 Setoff.  If an Event of Default  shall have occurred and is
continuing,  each Lender is hereby authorized at any time and from time to time,
without  notice to Borrower  (any such notice being hereby  expressly  waived by
Borrower),  to set off and apply any and all deposits (general or special,  time
or demand,  provisional or final) at any time held and other indebtedness at any
time  owing by such  Lender to or for the  credit  or the  account  of  Borrower
against any and all of the  obligations  of Borrower now or  hereafter  existing
under  this  Agreement,  such  Lender's  Notes,  or  any  other  Loan  Document,
irrespective  of whether or not the  Administrative  Agent or such Lender  shall
have made any demand under this  Agreement or such Lender's  Notes or such other
Loan Document and although such obligations may be unmatured. Each Lender agrees
promptly to notify Borrower (with a copy to the Administrative  Agent) after any
such setoff and application, provided that the failure to give such notice shall
not affect the validity of such setoff and application.  The rights and remedies
of  each  Lender  hereunder  are  in  addition  to  other  rights  and  remedies
(including,  without  limitation,  other rights of setoff) which such Lender may
have.

                       ARTICLE VI -- CONDITIONS PRECEDENT

         Section 6.1 Initial Advance.  The obligation of each Lender to make its
initial  Advance is subject to the condition  precedent that the  Administrative
Agent  shall  have  received  on or before  the day of such  Advance  all of the
following,  each dated (unless otherwise indicated) the date hereof, in form and
substance satisfactory to the Administrative Agent:

         (a) Resolutions. Resolutions of the Boards of Directors of Borrower and
each Guarantor  certified by the Secretary or an Assistant  Secretary of each of
them which authorize the execution, delivery, and performance by such Company of
this Agreement and/or the other Loan Documents to which such Company is or is to
be a party;

<PAGE>

         (b) Incumbency  Certificate.  A certificate of incumbency  certified by
the  Secretary  or  an  Assistant  Secretary  of  Borrower  and  each  Guarantor
certifying  the names of the officers of each such  Company,  authorized to sign
this  Agreement and each of the other Loan  Documents to which each such Company
is or is to be a party (including the certificates contemplated herein) together
with specimen signatures of such officers;

     (c) Articles of  Incorporation.  The articles of  incorporation of Borrower
and Guarantors certified by the applicable Secretary of State;

     (d) Bylaws.  The bylaws of Borrower and Litho certified by the Secretary or
an Assistant Secretary of each such Company;

     (e) Governmental  Certificates.  Certificates of the appropriate government
officials  of the  state  of  incorporation  of  Borrower  and  Litho  as to the
existence and good standing of each of them;

         (f)      Notes.  The Notes executed by Borrower;

     (g) Borrower Security  Agreement.  The Borrower Security Agreement executed
by Borrower;

     (h)      Guaranties.  The Guaranty Agreement executed by each Guarantor;

     (i)  Guarantor  Security  Agreements.  The  Guarantor  Security  Agreements
executed by the Guarantors;

     (j) Pledge Agreements.  The Pledge and Security  Agreements executed by the
Pledgors;

     (k) Financing  Statements.  Uniform Commercial Code financing statements or
amendments  executed by Borrower and each Guarantor and covering the Collateral,
as requested by Administrative Agent;

     (l) Stock  Certificates.  Stock  certificates  evidencing all stock pledged
pursuant  to  the  Borrower  Security  Agreement  and  each  Guarantor  Security
Agreement, as applicable, together with stock powers duly executed in blank;

     (m) Certificates of Title.  Original  certificates of title,  together with
executed  applications  for title,  for all vehicles used in connection with the
transportation  of  lithotripters  pledged  pursuant  to the  Borrower  Security
Agreement and the Guarantor Security Agreements;

     (n)  Insurance  Policies.  Copies of all  insurance  policies  required  by
Section  8.5,   together   with  loss  payee   endorsements   in  favor  of  the
Administrative  Agent,  for the  benefit  of the  Lenders,  with  respect to all
insurance policies covering Collateral;

         (o) UCC and Tax and  Judgment  Lien  Searches.  The  results of Uniform
Commercial Code searches showing all financing statements and other documents or
instruments,  and tax and judgment  lien  searches  showing all tax and judgment
liens,  on  file  against  Borrower  and  Litho  in  such  jurisdictions  as the
Administrative  Agent shall  require,  such  searches to be as of a date no more
than twenty (20) days prior to the date of the initial Advance;

     (p) Perfection Certificate. A Perfection Certificate,  in substantially the
form of Exhibit D hereto,  properly  completed and signed by the Chief Executive
or  Chief  Financial  Officer  or Vice  President-Finance  of  Borrower  and the
Guarantors;

<PAGE>

     (q) Opinion of Counsel.  Favorable  opinions as to the matters set forth in
Exhibit E hereto of Akin,  Gump,  Strauss,  Hauer & Feld,  L.L.P.,  Texas  legal
counsel to Borrower and the Guarantors;

     (r)  Attorneys'  Fees and  Expenses.  Evidence  that the costs and expenses
(including attorneys' fees) referred to in Section 13.1, to the extent incurred,
shall have been paid in full by Borrower;

     (s)  Fees.  Borrower  shall  have  paid to the  Agents,  Lenders,  and Lead
Arranger  the fees owed by Borrower to the Agents,  Lenders,  and Lead  Arranger
pursuant to the letter agreements between Borrower and Administrative Agent;

     (t) Federal Reserve Board Form U-1. For the Administrative Agent a properly
completed  Federal Reserve Board Form U-1 duly executed by each Company pledging
stock of another Company; and

         (u) No Material  Adverse Change.  No material adverse change shall have
occurred  since  September  30,  1999  in  the  business,   assets,  operations,
conditions  (financial  or  otherwise)  or prospects of the  Companies or in the
facts  and  information  delivered  to  Lenders  on or  prior to the date of the
initial Advance.

     Section 6.2 All Advances. The obligation of each Lender to make any Advance
(including  the  initial  Advance)  is  subject  to  the  following   additional
conditions precedent:

     (a) Advance Request Form. The Administrative Agent shall have received,  in
accordance  with Section 2.5, an Advance  Request Form executed by an authorized
officer of Borrower;

     (b) No Default. No Default shall have occurred and be continuing,  or would
result from such Advance;

         (c)  Representations  and Warranties.  All of the  representations  and
warranties  contained  in  Article  VII  hereof  and in each of the  other  Loan
Documents  shall be true and correct on and as of the date of such  Advance with
the same force and effect as if such  representations  and  warranties  had been
made on and as of such date, except to the extent that such  representations and
warranties  speak to a specific date or the facts on which such  representations
and warranties are based have been changed by  transactions  contemplated by the
Loan Documents;

     (d) Availability.  After giving effect to requested Advances, the remaining
availability  under  the  Commitment  shall be no less  than  the then  existing
Consolidated Earn-Out  Indebtedness,  as evidenced by the calculations set forth
in the Advance Request Form; and

         (e) Permitted Refractive  Acquisitions.  In connection with any Advance
the proceeds of which will be used to finance a Permitted Refractive Acquisition
by Prime Refractive,  L.L.C.,  Administrative Agent shall receive the following,
each in form and substance acceptable to Administrative Agent:

               (i) A subordinated  promissory note  substantially in the form of
          Exhibit L hereto made by Prime Refractive  Management,  L.L.C. payable
          to the  order  of  Borrower,  PMOI or  Prime  RVC,  together  with the
          guaranty thereof by Prime Refractive, L.L.C., and the pledge of assets
          (including any interests in Subsidiaries  and  Partnerships)  of Prime
          Refractive  Management,  L.L.C. and Prime Refractive,  L.L.C., and the
          interest of LASIK Investors,  L.L.C. in Prime Refractive,  L.L.C., all
          duly perfected and assigned to Administrative Agent;

<PAGE>

                  (ii) A subordination  agreement  substantially  in the form of
         Exhibit M hereto, between the payee of the subordinated note, the maker
         of the subordinated note,  Administrative Agent, and the administrative
         agent under the Advancing Term Facility; and

                  (iii)  Such  endorsements,   financing  statements,  corporate
         authorizations   and   other   documents    reasonably   requested   by
         Administrative Agent.

     (f) Additional Documentation.  The Administrative Agent shall have received
such additional  approvals,  opinions, or documents as are required by the terms
and provisions of this Agreement or any other Loan Document.

                  ARTICLE VII -- REPRESENTATIONS AND WARRANTIES

         To induce  the Agents  and the  Lenders  to enter into this  Agreement,
Borrower hereby represents and warrants to the Agents and the Lenders that:

         Section 7.1       Existence.

         (a) Corporate Existence. Each of the Companies (other than the Excepted
Subsidiaries and the Partnerships): (a) is a corporation duly organized, validly
existing,  and in  good  standing  under  the  laws of the  jurisdiction  of its
incorporation;  (b) has all requisite  corporate  power and authority to own its
assets and carry on its  business as now being or as  proposed to be  conducted;
and (c) is qualified to do business in all  jurisdictions in which the nature of
its business makes such qualification  necessary and where failure to so qualify
would have a material  adverse effect on the business,  condition  (financial or
otherwise),  operations,  or  properties  of the  Companies  taken  as a  whole,
Borrower,  or any Material  Subsidiary.  Each  Company  (other than the Excepted
Subsidiaries)  has the corporate  power and authority to execute,  deliver,  and
perform its  obligations  under this  Agreement and the other Loan  Documents to
which it is or may become a party.

         (b) Partnership Existence.  Each of the Partnerships:  (a) is a general
partnership,  limited  partnership or limited liability company, as appropriate,
duly  organized,  validly  existing,  and in good standing under the laws of the
jurisdiction  of its  formation;  (b) has all  requisite  partnership  power and
authority or company power and authority, as appropriate,  to own its assets and
carry on its  business as now being or as proposed to be  conducted;  and (c) is
qualified  to do  business  in all  jurisdictions  in which  the  nature  of its
business  makes such  qualification  necessary  and where  failure to so qualify
would have a material  adverse effect on the business,  condition  (financial or
otherwise),  operations,  or  properties  of the  Companies  taken  as a  whole,
Borrower, or any Material Subsidiary.

         Section  7.2  Financial  Statements.  Borrower  has  delivered  to  the
Administrative Agent audited consolidated  financial statements of the Companies
as  of  and  for  the  fiscal  year  ended  December  31,  1998,  and  unaudited
consolidated  financial  statements  of Borrower  for the nine (9) month  period
ended  September  30, 1999.  Such  financial  statements  have been  prepared in
accordance with GAAP, and fairly present, on a consolidated basis, the financial
condition of the Companies and Litho and the Partnerships, as appropriate, as of
the  respective  dates  indicated  therein and the results of operations for the
respective periods indicated therein.  There has been no material adverse change
in the business,  condition (financial or otherwise),  operations, or properties
of the Companies taken as a whole,  Borrower,  or any Material  Subsidiary since
the effective date of the most recent financial  statements  referred to in this
Section.

<PAGE>

         Section 7.3 Corporate Action: No Breach. The execution,  delivery,  and
performance  by each Company of this  Agreement and the other Loan  Documents to
which such  Company is or may become a party and  compliance  with the terms and
provisions  hereof  and  thereof  have been  duly  authorized  by all  requisite
corporate action (or, if such Company is a partnership, then partnership action)
on the part of such  Company  and do not and will not (a)  violate  or  conflict
with, or result in a breach of, or require any consent under (i) the articles of
incorporation  or bylaws of such Company (or, if such Company is a  partnership,
then the partnership  agreement of such Company),  (ii) any material  applicable
law, rule, or regulation or any material order, writ,  injunction,  or decree of
any  Governmental  Authority or arbitrator,  or (iii) any material  agreement or
instrument  to which such  Company is a party or by which such Company or any of
its property is bound or subject (other than agreements and instruments relating
to Debt which will be paid off with the proceeds of the initial Advance), or (b)
constitute a material default under any such agreement or instrument (other than
agreements  and  instruments  relating  to Debt  which will be paid off with the
proceeds of the initial Advance), or result in the creation or imposition of any
Lien (except as provided in Article V) upon any of the revenues or assets of any
of the Companies.

         Section 7.4 Operation of Business.  Each of the  Companies  (other than
the Excepted Subsidiaries) possesses all licenses, permits, franchises, patents,
copyrights,  trademarks, and tradenames, or rights thereto, necessary to conduct
their  respective  businesses  substantially  as now  conducted and as presently
proposed to be  conducted.  None of the  Companies  is in violation of any valid
rights of others with respect to any of the foregoing  (except where the failure
to do so would not have a material  adverse  effect on the  business,  condition
(financial or otherwise),  operations or properties of the Companies  taken as a
whole, Borrower, or any Material Subsidiary).

         Section 7.5 Litigation and Judgments.  As of the date hereof, except as
disclosed on Schedule 7.5 hereto,  there is no action, suit,  investigation,  or
proceeding before or by any Governmental  Authority or arbitrator pending, or to
the knowledge of Borrower, threatened against or affecting any of the Companies,
that would,  if  adversely  determined,  have a material  adverse  effect on the
business,  condition  (financial or otherwise),  operations or properties of the
Companies taken as a whole,  Borrower, or any Material Subsidiary or the ability
of  Borrower  to pay and  perform  the  Obligations.  There  are no  outstanding
judgments against any Company.

         Section 7.6 Rights in Properties; Liens. Each of the Companies has good
and  indefeasible  title to or valid  leasehold  interests  in their  respective
material  properties and assets,  real and personal,  including the  properties,
assets, and leasehold interests reflected in the financial  statements described
in Section 7.2, and none of the properties,  assets,  or leasehold  interests of
any Company is subject to any Lien, except as permitted by Section 9.2.

         Section 7.7 Enforceability.  This Agreement constitutes,  and the other
Loan Documents to which Borrower is a party,  when delivered,  shall  constitute
the legal,  valid,  and binding  obligations  of Borrower,  enforceable  against
Borrower  in  accordance  with  their  respective  terms,  except as  limited by
bankruptcy,  insolvency,  or other laws of general  application  relating to the
enforcement of creditors'  rights. The Loan Documents to which each Guarantor is
a party,  when  delivered,  shall  constitute  the  legal,  valid,  and  binding
obligations of such Guarantor,  enforceable against such Guarantor in accordance
with their respective  terms,  except as limited by bankruptcy,  insolvency,  or
other laws of general  application  relating to the  enforcement  of  creditors'
rights.

<PAGE>

         Section 7.8 Approvals.  No authorization,  approval, or consent of, and
no filing or registration with, any Governmental  Authority or third party is or
will be necessary for the execution, delivery, or performance by Borrower or any
Guarantor of this  Agreement and the other Loan  Documents to which  Borrower or
any  Guarantor  is or may become a party or for the  validity or  enforceability
thereof.

     Section 7.9 Debt. As of the date hereof, the Companies have no Debt, except
as disclosed on Schedule 7.9.

         Section   7.10  Taxes.   The   Companies   (other  than  the   Excepted
Subsidiaries) have filed or extended all tax returns (federal, state, and local)
required to be filed, including all income, franchise, employment, property, and
sales tax returns, and have paid all of their respective  liabilities for taxes,
assessments,  governmental  charges,  and other  levies that are due and payable
other than certain state tax returns  required to be filed on or before the date
hereof.  Except as previously  disclosed to the Administrative Agent in writing,
no  Company  knows of any  pending  investigation  of any of them by any  taxing
authority or of any pending but unassessed tax liability of any of them,  except
relating to the Excepted Subsidiaries.

         Section 7.11 Use of Proceeds;  Margin Securities. No Company is engaged
principally, or as one of its important activities, in the business of extending
credit for the  purpose of  purchasing  or  carrying  margin  stock  (within the
meaning  of  Regulations  T, U, or X of the Board of  Governors  of the  Federal
Reserve  System),  and no part of the  proceeds of any  Advance  will be used to
purchase or carry any margin stock or to extend credit to others for the purpose
of  purchasing  or carrying  margin  stock,  except for  purchases of Borrower's
capital stock permitted by Section 9.4 hereof.

         Section 7.12 ERISA.  The  Companies  are in  compliance in all material
respects with all applicable provisions of ERISA. Neither a Reportable Event nor
a Prohibited  Transaction  has occurred  and is  continuing  with respect to any
Plan.  No notice of intent to terminate a Plan has been filed,  nor has any Plan
been terminated.  No circumstances  exist which constitute grounds entitling the
PBGC to institute proceedings to terminate,  or appoint a trustee to administer,
a Plan, nor has the PBGC instituted any such proceedings.  None of the Companies
nor  any  ERISA   Affiliate  has  completely  or  partially   withdrawn  from  a
Multi-employer  Plan.  The  Companies  and each ERISA  Affiliate  have met their
minimum funding requirements under ERISA with respect to all of their Plans, and
the  present  value of all vested  benefits  under each Plan does not exceed the
fair market value of all Plan assets  allocable to such benefits,  as determined
on the most recent  valuation,  date of the Plan and in  accordance  with ERISA.
None of the Companies nor any ERISA  Affiliate has incurred any liability to the
PBGC under ERISA.

         Section 7.13  Disclosure.  All factual  information  (taken as a whole)
furnished  by or on behalf of  Borrower  in  writing  to any Agent or any Lender
(including,  without limitation,  all factual information  contained in the Loan
Documents) for purposes of or in connection with this Agreement,  the other Loan
Documents or any  transaction  contemplated  herein or therein is, and all other
such factual  information (taken as a whole) hereafter furnished by or on behalf
of Borrower in writing will be, true and  accurate in all  material  respects on
the date as of which such factual  information  is dated or certified and is not
(and such factual  information  (taken as a whole) hereafter  furnished will not
be)  incomplete  by omitting to state any facts  necessary  to make such factual
information  (taken as a whole) not  misleading in any material  respect at such
time in light of the  circumstances  under which such  factual  information  was
provided.

<PAGE>

         Section 7.14  Subsidiaries;  Partnerships.  Each of the Guarantors is a
direct or  indirect  wholly-owned  Subsidiary  of  Borrower,  and as of the date
hereof,  together with the Partnerships  listed on Schedule 3, constitute all of
the Subsidiaries of Borrower.  Schedule 7.14.1,  as the same may be amended from
time to time to reflect transactions permitted by this Agreement, sets forth the
outstanding shares of capital stock (or other ownership  interests) and the name
of  each  shareholder  of  each  of the  Subsidiaries  of  Borrower.  All of the
outstanding  capital  stock of Borrower  and each of its  Subsidiaries  has been
validly issued,  is fully paid, and is  nonassessable.  Schedule 7.14.2,  as the
same may be amended from time to time to reflect transactions  permitted by this
Agreement,  sets forth the outstanding partnership interests of the Partnerships
owned by each of the Companies.

         Section 7.15 Agreements.  Except for the Senior Subordinated Indenture,
the Senior  Subordinated  Notes,  and as set forth on Schedule 7.15, none of the
Companies is a party to any  indenture,  loan,  or credit  agreement,  or to any
lease or other  agreement or instrument,  or subject to any charter or corporate
restriction which could reasonably be expected to have a material adverse effect
on the business, condition (financial or otherwise), operations or properties of
the  Companies  taken as a whole,  Borrower,  or any Material  Subsidiary or the
ability of Borrower or any  Guarantor to pay and perform its  obligations  under
the Loan  Documents to which it is a party.  None of the Companies is in default
in any material respect in the performance, observance, or fulfillment of any of
the  obligations,  covenants,  or  conditions  contained  in  any  agreement  or
instrument to which it is a party, which default, in the aggregate with all such
other defaults, would have a material adverse affect on the business,  condition
(financial or otherwise),  operations or properties of the Companies  taken as a
whole, Borrower, or any Material Subsidiary.

     Section   7.16   Compliance   with   Legal    Requirements;    Governmental
Authorizations.

         (a) Except for the Excepted  Subsidiaries  and as set forth in Schedule
7.16.1:  (i) each Company is in  compliance  in all material  respects with each
Legal Requirement that is or was applicable to it or to the conduct or operation
of its  business  or the  ownership  or use of any of its  assets;  and  (ii) no
Company has received  any notice or other  communication  from any  Governmental
Authority or other Person of any event or circumstance  which could constitute a
violation of, or failure to comply with, any Legal Requirement.

         (b) Except for the Excepted  Subsidiaries  and as set forth in Schedule
7.16:  (i) each  Company  is in  material  compliance  with all of the terms and
requirements of each Governmental  Authorization  held by such Company;  (ii) no
Company has received  any notice or other  communication  from any  Governmental
Authority or other Person of, any event or circumstance which could constitute a
violation  of,  or  failure  to  comply  with,  any term or  requirement  of any
Governmental   Authorization,   or  of  any  actual  or  potential   revocation,
withdrawal,  cancellation  or termination of, or material  modification  to, any
Governmental  Authorization;  (iii) all applications required to have been filed
for the renewal of any required Governmental Authorizations have been duly filed
on a timely basis with the appropriate Governmental  Authorities,  and all other
filings   required  to  have  been  made  with  respect  to  such   Governmental
Authorizations  have  been  duly  made on a timely  basis  with the  appropriate
Governmental Authorities;  (iv) all Governmental Authorizations of the Companies
are  transferable to the Companies;  (v) upon  consummation of the  transactions
contemplated  hereby,  the Companies  will  lawfully hold all such  Governmental
Authorizations; and (vi) none of such Governmental Authorizations will terminate
upon  consummation  of the  transactions  contemplated  hereby.  Except  for the
Excepted  Subsidiaries  and as set forth on Schedule 7.16, each of the Companies
possesses the necessary Governmental Authorizations (i) necessary to permit each
Company to lawfully conduct and operate its respective business in the manner it
currently  conducts and operates such business and to permit such Company to own
and use its  assets  in the  manner  in which it  currently  owns and uses  such
assets, and (ii) necessary to permit each Company,  upon the consummation of the
transactions  contemplated  hereby, to lawfully conduct and operate its business
and to permit each Company to own and use its assets,  where the failure to have
such  Governmental  Authorization  would have a material  adverse  effect on the
business,  condition  (financial or otherwise),  operations or properties of the
Companies taken as a whole, Borrower, or any Material Subsidiary.

<PAGE>

     Section 7.17 Investment Company Act. No Company is an "investment  company"
within the meaning of the Investment Company Act of 1940, as amended.

         Section  7.18  Public  Utility  Holding  Company  Act.  No Company is a
"holding  company"  or a  "subsidiary  company"  of a  "holding  company"  or an
"affiliate" of a "holding  company" or a "public  utility" within the meaning of
the Public Utility Holding Company Act of 1935, as amended.

     Section 7.19 Environmental  Matters.  Except as disclosed on Schedule 7.19,
as the same may be amended from time to time, hereto:

         (a)  Each of the  Companies  and all of  their  respective  properties,
assets,  and  operations  are in  compliance  in all material  respects with all
Environmental Laws. No Company is aware of, nor have any of them received notice
of, any past, present, or future conditions,  events, activities,  practices, or
incidents  which may  interfere  with or  prevent  the  material  compliance  or
continued  material  compliance  of any Company with all material  Environmental
Laws; and

         (b) The  Companies  have  obtained all material  permits,  licenses and
authorizations  that are required under applicable  Environmental  Laws, and all
such  permits are in good  standing  and each  Company is in  compliance  is all
material respects with all of the terms and conditions of such permits.

         Section 7.20 Year 2000 Compliance. Borrower represents that it is aware
of the possible impact of the year 2000 problem (that is, the risk that computer
applications may not be able to properly perform date-sensitive  functions after
December  31,  1999)  upon its  computer  applications  and  on-going  business.
Borrower  represents that any corrective action necessary will be taken and that
the year 2000  problem  will not  result  in a  material  adverse  change in the
Companies' business condition (financial or otherwise),  operations,  properties
or prospects, or ability to repay the Obligations.

                       ARTICLE VIII -- POSITIVE COVENANTS

         Borrower  hereby  covenants and agrees that, as long as the Obligations
or any part thereof are outstanding or any Lender has any Commitment  hereunder,
Borrower will perform and observe each of the following positive covenants:

     Section  8.1   Reporting   Requirements.   Borrower  will  furnish  to  the
Administrative Agent and each Lender:

         (a) Annual Financial Statements. As soon as available, and in any event
within  ninety-five  (95) days after the end of each  fiscal  year of  Borrower,
beginning  with the fiscal year ending  December  31, 1998, a copy of the annual
audit report of the Companies for such fiscal year containing, on a consolidated
basis, balance sheets and statements of income, retained earnings, and cash flow
as at the end of such  fiscal  year and for the twelve  (12)-month  period  then
ended,  in each case  setting  forth in  comparative  form the  figures  for the
preceding fiscal year,  audited by independent  certified public  accountants of
recognized standing, and accompanied by an opinion of such independent certified
public accountants stating that such report has been prepared in accordance with
GAAP;

<PAGE>

         (b) Monthly  Financial  Statements.  As soon as  available,  and in any
event  within forty (40) days after the end of each month of each fiscal year of
Borrower, a copy of an unaudited financial report of the Companies as of the end
of such month and for the portion of the fiscal year then ended, containing,  on
a  consolidated  basis,  balance  sheets and  statements  of income and retained
earnings,  in each case setting  forth in  comparative  form the figures for the
corresponding  period  of the  preceding  fiscal  year,  certified  by the chief
financial  officer of Borrower to have been prepared in accordance with GAAP and
to fairly and accurately  present  (subject to year-end audit  adjustments)  the
financial   condition  and  results  of  operations  of  the  Companies,   on  a
consolidated basis, at the date and for the periods indicated therein;

         (c) Quarterly Financial  Statements.  As soon as available,  and in any
event within  forty-five  (45) days after the end of each quarter of each fiscal
year of Borrower, a copy of an unaudited financial report of the Companies as of
the end of such  quarter  and for the  portion  of the fiscal  year then  ended,
containing,  on a consolidated  basis,  balance sheets and statements of income,
retained earnings, and cash flow, in each case setting forth in comparative form
the figures for the corresponding period of the preceding fiscal year, certified
by the chief  financial  officer of Borrower to have been prepared in accordance
with GAAP and to fairly  and  accurately  present  (subject  to  year-end  audit
adjustments) the financial condition and results of operations of the Companies,
on a consolidated basis, at the date and for the periods indicated therein,  and
a copy of an unaudited  financial report of Prime RVC and its Subsidiaries as of
the end of such quarter  beginning with the fiscal quarter ending March 31, 2000
and for the portion of the fiscal year then ended, containing, on a consolidated
and  consolidating  basis,  balance  sheets and  statements of income,  retained
earnings,  and cash flow,  in each case setting  forth in  comparative  form the
figures for the corresponding  period of the preceding fiscal year, certified by
the chief  financial  officer or treasurer of Borrower to have been  prepared in
accordance with GAAP and to fairly and accurately  present  (subject to year-end
audit  adjustments)  the financial  condition and results of operations of Prime
RVC and its Subsidiaries, on a consolidated and consolidating basis, at the date
and for the periods indicated therein;

         (d) Compliance  Certificate.  Concurrently with the delivery of each of
the financial  statements  referred to in Section  8.1(a) and within  forty-five
(45) days after the end of each of the first  three (3) fiscal  quarters of each
fiscal year of Borrower,  a certificate of the chief executive,  chief financial
officer or treasurer of Borrower,  in  substantially  the form of Exhibit F, (i)
stating  that to such  officer's  knowledge,  no  Default  has  occurred  and is
continuing,  or if a Default has occurred and is  continuing,  a statement as to
the nature  thereof and the action  that is  proposed  to be taken with  respect
thereto,  and (ii) showing in reasonable  detail the calculations  demonstrating
compliance with Article X;

     (e) Accounts Receivable Aging Report. As soon as available and in any event
within  forty  (40) days  after the end of each  month,  an aged  listing of the
accounts  receivable of each of Borrower and its  Subsidiaries  as of the end of
such month in a form reasonably satisfactory to the Administrative Agent;

     (f)  Business  Plan and Budget.  As soon as  available  and in any event by
January  15 of each  year,  a copy of the annual  budget  and  business  plan of
Borrower and its Subsidiaries for such fiscal year, together with details of the
assumptions, if any, underlying such budget and business plan;

     (g)  Management  Letters.  Promptly  upon  receipt  thereof,  a copy of any
management  letter or written  report  submitted  to any Company by  independent
certified public accountants with respect to the business,  condition (financial
or otherwise), operations, or properties of any Company;

<PAGE>

         (h) Notice of  Litigation.  Promptly  after the  commencement  thereof,
notice of all actions,  suits, and proceedings before any Governmental Authority
or arbitrator affecting Borrower or any of its Subsidiaries which, if determined
adversely  to Borrower  or any such  Subsidiary,  could have a material  adverse
effect  on  the  business,  condition  (financial  or  otherwise),  options,  or
properties of Borrower, any Subsidiary or the Companies (taken as a whole);

         (i) Notice of Default. As soon as possible and in any event within five
(5) days after  Borrower  knows of the  occurrence  of each  Default,  a written
notice  setting  forth the details of such Default and the action that  Borrower
has taken and proposes to take with respect thereto;

         (j) ERISA Reports. Promptly after the filing or receipt thereof, copies
of all reports,  including  annual reports,  and notices which any Company files
with or receives from the PBGC or the U.S.  Department of Labor under ERISA; and
as soon as  possible  and in any event  within  five (5) days after any  Company
knows or has reason to know that any Reportable Event or Prohibited  Transaction
has  occurred  with  respect to any Plan or that the PBGC,  or any  Company  has
instituted or will  institute  proceedings  under Title IV of ERISA to terminate
any Plan, a certificate of the chief financial officer of Borrower setting forth
the  details  as to such  Reportable  Event or  Prohibited  Transaction  or Plan
termination and the action that Borrower proposes to take with respect thereto;

         (k) Reports to Other Creditors.  Promptly after the furnishing thereof,
copies  of  any  statement  or  report  furnished  by  Borrower  or  any  of its
Subsidiaries to any other creditor to which any Company owes $250,000.00 or more
or to the trustee under the Senior Subordinated Indenture, pursuant to the terms
of any  indenture,  loan,  or  credit or  similar  agreement  and not  otherwise
required to be furnished to the Administrative Agent and the Lenders pursuant to
any other clause of this Section;

         (l) Proxy Statements,  Etc. As soon as available,  one (1) copy of each
financial statement,  report,  notice or proxy statement sent by Borrower to its
stockholders  generally  and one (1) copy of each  regular,  periodic or special
report,  registration  statement,  or  prospectus  filed  by  Borrower  with any
securities  exchange or the Securities and Exchange  Commission or any successor
agency including, without limitation, all Forms 10-K, 10-Q and 8-K and all other
periodic reports required to be filed under the Securities  Exchange Act of 1934
and the rules and regulations promulgated thereunder;

         (m)  Partnership  Lists.  As soon as  available,  and in any  event (a)
within thirty (30) days after the Administrative Agent requests such information
from  Borrower,  a list of the names and  addresses of each partner or member of
each of the  Partnerships  and  percentage  ownership  by each  Company  of each
Partnership;

         (n) Governmental Authorizations. Upon the request of the Administrative
Agent, but not more often than one (1) time during each fiscal year of Borrower,
a complete and accurate list of each Governmental  Authorization held by each of
Companies or that  otherwise  relate to the business of, or to any of the assets
owned or used by, each of the Companies;

         (o) Dilution  Reports.  Promptly upon the  occurrence of any Restricted
Transfer (as hereinafter  defined), a report setting forth the occurrence of any
Restricted Transfer, including the name of the Partnership, purchasers, purchase
price,   and  EBITDA  for  the   immediately   preceding  four  fiscal  quarters
attributable  thereto, and also of the contribution of any Partnership assets to
any  other  Partnership,   including  the  names  of  the  Partnerships,  assets
transferred, value thereof and consideration received;

<PAGE>

         (p) Partnership Actions.  Promptly after the incurrence thereof, notice
of any Partnership's (i) incurrence of Debt, (ii) change in accounting treatment
or reporting practices (which change shall not affect any reporting requirements
set  forth  herein  or the Loan  Documents),  except  as  permitted  by GAAP and
disclosed to the Administrative  Agent, (iii) change in tax reporting treatment,
except  as  permitted  by law,  (iv)  amendment  of any  partnership  agreement,
regulations,  or management  agreement  between such Partnership and any Company
and copies of any such  amendment  certified  by an officer of Borrower as being
true and correct, and (v) change in its insurance; and

     (q)  General  Information.  Promptly,  such  other  information  concerning
Borrower or any of its  Subsidiaries as the  Administrative  Agent or any Lender
may from time to time reasonably request.

         Section 8.2  Maintenance  of Existence;  Conduct of Business.  Borrower
will  preserve  and  maintain  its  corporate  existence  and all of its leases,
privileges, licenses, permits, franchises,  qualifications,  and rights that are
necessary or desirable in the ordinary  conduct of its  business.  Borrower will
cause each of its Subsidiaries other than the Excepted Subsidiaries, to preserve
and maintain its corporate,  partnership  or other similar  existence and all of
its leases, privileges, licenses, permits, franchises, qualifications and rights
that are necessary or desirable in the ordinary conduct of its business, except,
in each case, where failure to do so would not have a material adverse effect on
the business,  condition  (financial or otherwise),  operations or properties of
the Companies taken as a whole,  Borrower, or any Material Subsidiary.  Borrower
will conduct,  and will cause each of its Subsidiaries to conduct,  its business
in an orderly and efficient manner in accordance with good business practices.

         Section 8.3  Maintenance of Properties.  Borrower will maintain,  keep,
and  preserve,  and  cause  each of its  Subsidiaries  to  maintain,  keep,  and
preserve, all of its properties (tangible and intangible) necessary or useful in
the proper conduct of its business in good working order and condition,  except,
in each case,  as  permitted by Section 9.8 or 9.9 or where the failure to do so
would not have a material adverse effect on the business,  condition  (financial
or  otherwise),  operations or  properties  of the  Companies  taken as a whole,
Borrower, or any Material Subsidiary.

         Section 8.4 Taxes and Claims. Borrower will pay or discharge,  and will
cause each of its Subsidiaries other than the Excepted  Subsidiaries,  to pay or
discharge,  at or before maturity or before becoming delinquent (a) all material
taxes, levies, assessments, and governmental charges imposed on it or its income
or profits or any of its material  property,  and (b) all material lawful claims
for labor,  material,  and supplies,  which, if unpaid, might become a Lien upon
any of its property; provided, however, that no Company shall be required to pay
or discharge any tax, levy,  assessment,  or governmental  charge which is being
contested in good faith by appropriate  proceedings  diligently pursued, and for
which adequate reserves have been established.

<PAGE>

         Section 8.5 Insurance.  Borrower will maintain,  and will cause each of
its Subsidiaries to maintain (except in the case of the  Partnerships,  in which
case Borrower shall maintain for the  Partnerships),  insurance with financially
sound and reputable  insurance companies in such amounts and covering such risks
as is usually carried by corporations  engaged in similar  businesses and owning
similar  properties in the same general  areas in which the  Companies  operate,
consistent  with past practices of the Companies and to the extent  available on
commercially reasonable terms, provided that in any event Borrower will maintain
and cause each of its Subsidiaries  (except in the case of the Partnerships,  in
which case Borrower shall maintain for the  Partnerships) to maintain  workmen's
compensation  insurance,  property  insurance,  comprehensive  general liability
insurance, professional liability insurance, and business interruption insurance
reasonably   satisfactory  to  the  Lenders.   Each  insurance  policy  covering
Collateral shall name the Administrative Agent as loss payee, for the benefit of
the Lenders, as its interests may appear and shall provide that such policy will
not be canceled or reduced without thirty (30) days' prior written notice to the
Administrative  Agent.  Borrower will annually provide the Administrative  Agent
with all  certificates  of  insurance  evidencing  all  policies of insurance of
Borrower and its Subsidiaries.

         Section 8.6 Inspection  Rights. At any reasonable time and from time to
time after reasonable notice to Borrower,  Borrower will permit,  and will cause
each of its Subsidiaries to permit,  representatives of the Administrative Agent
and each Lender to examine,  copy, and make extracts from its books and records,
to visit and inspect its  properties,  and to discuss its business,  operations,
and financial  condition with its officers,  and  independent  certified  public
accountants.  Prior to removing  any such  copies or  extracts  from a Company's
premises,  such  Company's   representatives  shall  be  provided  a  reasonable
opportunity to review such information and mark or identify it as "confidential"
or "confidential information" as reasonably deemed appropriate by such Company.

         Section 8.7 Keeping Books and Records. Borrower will maintain, and will
cause each of its  Subsidiaries to maintain,  proper books of record and account
in which full,  true, and correct  entries in conformity with GAAP shall be made
of all dealings and transactions in relation to its business and activities.

         Section 8.8 Compliance with Laws.  Borrower will comply, and will cause
each of its Subsidiaries to comply,  in all material  respects with all material
applicable laws,  rules,  regulations,  orders,  and decrees of any Governmental
Authority or arbitrator.

         Section 8.9 Compliance with Agreements.  Borrower will comply, and will
cause each of its  Subsidiaries  to comply,  in all material  respects  with all
agreements, contracts, and instruments binding on it or affecting its properties
or business, except where the failure to do so would not have a material adverse
effect on the  business,  condition  (financial  or  otherwise),  operations  or
properties  of the  Companies  taken  as a  whole,  Borrower,  or  any  Material
Subsidiary.

         Section 8.10 Further Assurances. Borrower will (a), and will cause each
of its Subsidiaries  (other than the  Partnerships) to, execute and deliver such
further  agreements  and  instruments  and take  such  further  action as may be
reasonably requested by the Administrative Agent to carry out the provisions and
purposes of this  Agreement and the other Loan Documents and, (b) and will cause
each of its Subsidiaries (including the Partnerships) to, create,  preserve, and
perfect the Liens of the  Administrative  Agent, for the benefit of the Lenders,
in the Collateral.

         Section 8.11 ERISA.  Borrower  will comply,  and will cause each of its
Subsidiaries  to comply,  with all minimum funding  requirements,  and all other
material  requirements,  of ERISA, if applicable,  so as not to give rise to any
liability thereunder.

         Section 8.12 Information  Relating to Proposed  Acquisitions.  Borrower
will use its best  efforts  to keep the  Administrative  Agent  and the  Lenders
informed  of the  relevant  information  and  status of and will  share with the
Administrative  Agent and the Lenders and provide copies to the extent possible,
of all material due diligence  information  relating to any proposed Acquisition
with respect to which Borrower or any Subsidiary  enters into a letter of intent
or acquisition agreement, during the term of this Agreement.

<PAGE>

         Section  8.13  After-Acquired   Subsidiaries.   Concurrently  upon  the
formation  or  Acquisition  by Borrower  or any  Guarantor  of any  Wholly-Owned
Subsidiary  after  the date  hereof  (pursuant  to a  Permitted  Acquisition  or
otherwise)   (an   "After-Acquired   Subsidiary"),   Borrower  shall  cause  the
After-Acquired  Subsidiary to deliver  articles of  incorporation,  bylaws,  and
resolutions (or other corresponding  constituent documents) and such opinions as
the  Administrative  Agent shall  require  and to execute a Guaranty,  Guarantor
Security Agreement,  and Pledge Agreement (if applicable),  as shall be required
by the  Administrative  Agent to  create  first  priority  Liens in favor of the
Administrative  Agent,  for the benefit of the Lenders,  in such  After-Acquired
Subsidiary's assets, to secure the Obligations.

         Section 8.14 Syndication  Cooperation.  Borrower  acknowledges that the
Agents intend  promptly to commence to syndicate the  Commitments of the Lenders
in accordance  with the provisions of Section 13.6.  Borrower agrees to actively
assist  Agents  and  their   Affiliates  in  achieving  a  syndication  that  is
satisfactory  to Agents and Borrower and in preparing  information  requested by
Agents in connection  with arranging and  syndication of the  Commitments of the
Lenders  and to take  such  other  action  deemed  necessary  by Agents or their
Affiliates,  including  the  holding  of a formal  presentation  to  prospective
Lenders to achieve a successful  syndication of the  Commitments by Agents.  The
syndication  efforts will be accomplished  by a variety of means,  including the
preparation  of  a  confidential  information  memorandum  and  other  marketing
materials,  direct contact  during the  syndication  between  senior  management
(including, but not limited to, the chief executive officer, the chief financial
officer and treasurer of Borrower)  and advisors and  Affiliates of Borrower and
the proposed syndicate Lenders.

                        ARTICLE IX -- NEGATIVE COVENANTS

         Borrower  hereby  covenants and agrees that, as long as the Obligations
or any part thereof are outstanding or any Lender has any Commitment  hereunder,
Borrower will perform and observe the following negative covenants:

         Section 9.1A Debt. Borrower will not incur,  create,  assume, or permit
to exist,  nor permit any of its Subsidiaries  (other than the  Partnerships) to
incur, create, assume, or permit to exist, any Debt, except:

          (a) Debt  owed to the  Agents  and the  Lenders  pursuant  to the Loan
     Documents;

          (b)  Existing Debt described on Schedule 7.9 hereto;

     (c)  The  Exchange  Notes  and  guaranties   thereof  by  any  Wholly-Owned
Subsidiary;

          (d) Debt owed to Borrower or to any Wholly-Owned Subsidiary;

         (e) Debt in an aggregate  principal amount not to exceed  $2,000,000.00
at any time  outstanding  the proceeds of which are used by Borrower or Litho to
purchase equipment, other than lithotripters, prostatrons, and lasers;

     (f) Any Company's  obligations as general  partner of a Partnership for the
Debt of such Partnership;

     (g) Any Company's Guarantee of Debt of any Partnership,  if such Company is
a general partner of such Partnership;

     (h) Debt not exceeding $1,750,000 in outstanding  principal amount incurred
by AK Associates,  L.L.C.  in connection with the acquisition and improvement of
real estate;

         (i)      Any Financial Hedge; and

<PAGE>

         (j)      The Advancing Term Facility and Guarantees thereof.

         Section 9.1B Debt of Refractive Entities. The Companies will not incur,
create,  assume,  or permit to exist Debt (other than the  Obligations  and Debt
under the Advancing Term Facility) exceeding $6,500,000 in outstanding principal
amount  incurred  to finance or  refinance  acquisitions  of  equipment  used in
correcting  refractive  error  of the eye,  provided  that of such  Debt,  Prime
Refractive Management,  L.L.C., any of its Subsidiaries,  or any Partnerships in
which  they are a  partner  may only be liable  for  $4,000,000  in  outstanding
principal amount of such Debt.

         Section  9.2  Limitation  on Liens.  Borrower  will not incur,  create,
assume,  or permit to exist, nor permit any of its Subsidiaries  (other than the
Partnerships) to incur, create, assume, or permit to exist, any Lien upon any of
their respective properties, assets, or revenues, whether now owned or hereafter
acquired, except:

         (a)      Liens disclosed on Schedule 9.2;

     (b) Purchase money Liens securing Debt  permitted by Section  9.1A(d),  (e)
and (k);

     (c) Liens in favor of the  Administrative  Agent,  for the  benefit  of the
Lenders or the counter-party under any Financial Hedge;

         (d) Encumbrances consisting of minor easements, zoning restrictions, or
other  restrictions on the use of real property that do not  (individually or in
the aggregate)  materially affect the value of the assets encumbered  thereby or
materially impair the ability of Borrower or any of its Subsidiaries to use such
assets in their  respective  businesses,  and none of which is  violated  in any
material respect by existing or proposed structures or land use;

         (e) Liens for taxes,  assessments,  or other governmental charges which
are not  delinquent  or which are being  contested  in good  faith and for which
adequate reserves have been established;

     (f)  Liens of  mechanics,  materialmen,  warehousemen,  carriers,  or other
similar  statutory  Liens  securing  obligations  that  are  not yet due and are
incurred in the ordinary course of business;

         (g) Liens  resulting  from good faith  deposits  to secure  payments of
workmen's  compensation  or other  social  security  programs  or to secure  the
performance of tenders,  statutory  obligations,  surety and appeal bonds, bids,
contracts  (other  than for  payment of Debt),  or leases  made in the  ordinary
course of business;

     (h)  Lien  on real  property  and  improvements  of AK  Associates,  L.L.C.
securing Debt described in Section 9.1A(h) above;

         (i) Liens  securing the Advancing  Term  Facility;  provided such Liens
granted by Borrower and the  Guarantors are  subordinated  in form and substance
satisfactory  to  the  Administrative  Agent  to  the  Liens  in  favor  of  the
Administrative Agent; and

         (j)  Liens  securing   subordinated  Debt  owing  to  PMOI  or  another
Guarantor,  the proceeds of which were used to finance a portion of the purchase
price of a Permitted Refractive Acquisition.

<PAGE>

     Section 9.3  Mergers,  Etc.  Except upon the prior  written  consent of the
Required  Lenders,  neither  Borrower nor any Guarantor will become a party to a
merger or consolidation,  except: (a) any of R.R. Litho, Inc., Ohio Litho, Inc.,
Prime  Diagnostic  Services,  Inc.,  Prime  Diagnostic  Corp. of Florida,  Prime
Practice Management,  Inc., Prime Cardiac Rehabilitation  Services,  Inc., Prime
Lithotripsy  Services,  Inc.,  Alabama Renal Stone  Institute,  Inc.,  and Prime
Kidney  Stone  Treatment,  Inc.  may merge or  consolidate  into  Prime  Medical
Operating,  Inc., so long as (w) Prime Medical Operating,  Inc. is the surviving
entity,  (x) no Default or Event of Default  exists or would exist as the result
of such merger or consolidation,  (y) no partnership agreement to which any such
Guarantor is a party would be breached by such merger or consolidation,  and (z)
Borrower and the applicable  Guarantors  give  Administrative  Agent at least 15
Business Days prior written notice of any proposed merger or  consolidation  and
execute and deliver any Guaranty Agreement, Guarantor Security Agreement, Pledge
Agreement,    Uniform   Commercial   Code   financing   statements,    corporate
documentation,  and opinions of counsel as required by the Administrative  Agent
to create or continue first priority Liens in favor of the Administrative Agent,
for the benefit of the Lenders,  in the assets of the surviving entity to secure
the Obligations, and (b) in connection with any Permitted Acquisition, Permitted
Other  Business  Acquisition,  or Permitted  Refractive  Acquisition  so long as
Borrower or a Guarantor is the surviving entity. Borrower will not, and will not
permit  any of its  Subsidiaries  (other  than the  Partnerships)  to,  wind-up,
dissolve or  liquidate  itself,  except as permitted  in  subsection  (a) above.
Except as otherwise permitted by this Agreement, Borrower will not, and will not
permit  any of its  Subsidiaries  to,  form,  incorporate,  acquire  or make any
investment in any  Subsidiary,  except (a) the  Subsidiaries  listed on Schedule
7.14.1,  (b)  Subsidiaries  acquired or formed through a Permitted  Acquisition,
Permitted Other Business Acquisition, Permitted Passive Investment, or Permitted
Refractive  Acquisition,  (c)  Subsidiaries  formed or acquired through the BDEC
Acquisition, or the Horizon Acquisition and (d) Wholly-Owned Subsidiaries formed
in accordance with Section 8.13.

         Section 9.4 Restricted  Payments.  Borrower will not declare or pay any
dividends or make any other payment or distribution  (whether in cash, property,
or obligations) on account of its capital stock, or redeem, purchase, retire, or
otherwise acquire any of its capital stock, or permit any of its Subsidiaries to
purchase or otherwise  acquire any capital  stock of Borrower,  or set apart any
money  for a  sinking  or  other  analogous  fund  for  any  dividend  or  other
distribution on its capital stock or for any redemption,  purchase,  retirement,
or other acquisition of any of its capital stock; provided,  however, that, from
the date hereof through and including the Termination Date,  Borrower may redeem
or retire and/or the Companies may purchase shares of Borrower's  capital stock,
whether through issuance and performance of a put agreement,  or otherwise,  for
an aggregate  consideration  of no more than  $11,993,000 on and after September
30, 1999,  provided that upon  completion of such  purchases or  redemptions  no
Default or Event of Default would exist or be continuing,  and provided  further
that the  proceeds  from the sale of any Stock  previously  redeemed by Borrower
shall increase the limit hereunder dollar for dollar to the extent such proceeds
have been applied as set forth in Section  3.3(b).  Borrower shall not permit to
exist any  arrangement,  agreement,  or corporate  governance  agreement,  which
directly or indirectly  prohibits or restricts any Subsidiary  from declaring or
paying  any  dividend  or  distribution,   on  account  of  its  capital  stock,
partnership,  limited liability company, or other ownership interests,  provided
that  provisions in such  agreements  providing for the payment of Debt prior to
the payment of any dividend or distribution shall not violate this Section.

         Section 9.5 Investments.  Borrower will not make, nor permit any of its
Subsidiaries  to make,  any  advance,  loan,  extension  of  credit,  or capital
contribution  to or  investment  in, or  purchase  or own,  or permit any of its
Subsidiaries to purchase or own, any stock, bonds, notes,  debentures,  or other
securities of, any Person, except:

<PAGE>

         (a) The Companies,  or any of them, may purchase (i) readily marketable
direct  obligations  of the United States of America or any agency  thereof with
maturities of one year or less from the date of acquisition,  (ii) fully insured
certificates  of deposit  with  maturities  of one year or less from the date of
acquisition  issued by any  commercial  bank  operating in the United  States of
America  having  capital  and  surplus  in excess of  $1,000,000,000,  and (iii)
commercial  paper of a domestic  issuer if at the time of purchase such paper is
rated in one (1) of the two (2) highest rating categories of Standard and Poor's
Rating  Group,  a division of McGraw  Hill,  Inc.,  a New York  corporation,  or
Moody's Investors Service, Inc.;

         (b)  The  Companies,  or any of  them,  may  make  loans  to  officers,
directors  and  employees  of any of them  provided  such  loans are made in the
ordinary  course of business,  and are in an aggregate  principal  amount of not
more than $200,000.00 at any time outstanding;

     (c)  Borrower may  continue to hold  capital  stock of American  Physicians
Service Group, Inc. held by Borrower on the date hereof;

         (d) The Borrower and Guarantors may create new Subsidiaries, hold stock
in Subsidiaries  and  themselves,  and engage in the  transactions  permitted by
Section 9.3 hereof, provided that Borrower complies with Section 8.13;

         (e)      Existing Permitted Passive Investments;

         (f) Permitted Acquisitions,  Permitted Other Business Acquisitions, and
Permitted Passive Investments;  provided however,  that Permitted  Acquisitions,
Permitted Other Business Acquisitions, and Permitted Passive Investments made by
Companies  other than the Borrower or a Guarantor shall not in the aggregate for
all such Companies exceed the lesser of: (a) $3,000,000.00; and (ii) 3% of Total
Equity;

         (g)      Permitted Refractive Acquisitions;

          (h)  Borrower may make a loan to AK  Associates,  L.L.C.  described in
               Section 9.1A(h) and Section 9.2(h) above;

         (i)      Any Financial Hedge;

         (j)      the BDEC Acquisition, and the Horizon Acquisition;

          (k)  the  $200,000  working  capital line of credit from PMOI or Prime
               RVC to Prime Refractive, L.L.C., in form and substance acceptable
               to Administrative Agent;

          (l)  the formation of and, as  applicable,  contribution  of assets to
               Prime/BDR Acquisition,  L.L.C.,  Prime/BDEC Acquisition,  L.L.C.,
               Prime  Refractive,   L.L.C.,  and  Prime  Refractive  Management,
               L.L.C.;

          (m)  the   aggregate   $11,035,000   loans  from  PMOI  to   Prime/BDR
               Acquisition,  L.L.C.,  the proceeds of which were used to finance
               the Horizon Acquisition;

          (n)  the purchase by PMOI of the  interests in Prime/BDR  Acquisition,
               L.L.C. owned by the other owners of Prime/BDR Acquisition, L.L.C.
               on  the  dates  and  for  the  purchase  price  required  by  the
               Contribution  Agreement (the  "Contribution  Agreement")  entered
               into  among  PMOI,  Borrower,   Prime/BDR  Acquisition,   L.L.C.,
               Prime/BDEC  Acquisition,  L.L.C., Mark Rosenberg,  the sellers of
               the  refractive  surgery eye center  assets,  and  certain  other
               parties; and

<PAGE>

         (o)      loans  by PMOI or any  other  Guarantor  to  LASIK  Investors,
                  L.L.C. required by the Contribution Agreement in effect on the
                  date  hereof,  so long as such  loans are  secured  by a first
                  priority   Lien   in  the   interests   being   acquired   and
                  Administrative  Agent on  behalf  of the  Lenders  receives  a
                  perfected, first priority lien in such loan and the Collateral
                  therefor.

         Section 9.6 Limitation on Issuance of Capital Stock.  Borrower will not
permit any of its Subsidiaries to at any time issue,  sell, assign, or otherwise
dispose of (a) any of its capital stock or other  ownership  interests,  (b) any
securities  exchangeable  for or  convertible  into or  carrying  any  rights to
acquire  any of its  capital  stock or  other  ownership  interests,  or (c) any
option,  warrant,  or other right to acquire  any of its capital  stock or other
ownership  interests;  provided,  however,  that any  Subsidiary of Borrower may
issue, sell, assign or otherwise dispose of its capital stock or other ownership
interests,  or securities  exchangeable for its capital stock or other ownership
interests, to Borrower or any other Wholly-Owned Subsidiary.

         Section 9.7 Transactions With Affiliates. Borrower will not enter into,
and will not permit any of its  Subsidiaries  to enter  into,  any  transaction,
including,  without limitation,  the purchase,  sale, or exchange of property or
the rendering of any service,  with any Affiliate of Borrower or any  Subsidiary
of Borrower,  except in the ordinary  course of Borrower's or such  Subsidiary's
business  and upon fair and  reasonable  terms no less  favorable to Borrower or
such Subsidiary than would be obtained in a comparable arm's-length  transaction
with a Person not an Affiliate of Borrower or such Subsidiary.  No Company shall
make any loan,  advance,  investment,  or  transfer  any assets to any  Excepted
Subsidiary,  so long as such Excepted  Subsidiary is not in good standing  where
incorporated.

<PAGE>

         Section  9.8  Disposition  of Assets.  Borrower  will not sell,  lease,
assign,  transfer,  or otherwise dispose of any of its assets, nor permit any of
its  Subsidiaries  (other  than  the  Partnerships)  to do so with  any of their
respective  assets,  except  (subject to the mandatory  prepayments  required by
Section 3.3) (a)  inter-Company  transfers  between  Borrower and a Wholly-Owned
Subsidiary or between  Wholly-Owned  Subsidiaries,  (b)  dispositions of assets,
other than  lithotripters,  in the ordinary course of business for consideration
of up to an aggregate amount of $1,000,000.00 during the term of this Agreement,
(and the Administrative Agent agrees to execute and deliver releases of Liens in
connection with such  dispositions),  (c)  dispositions by any Company of assets
used in  connection  with cardiac  rehabilitation  or  diagnostic  imaging,  (d)
dispositions of any tangible assets that are worn or obsolete, (e) contributions
of assets to Prime/BDEC Acquisition, L.L.C. as contemplated pursuant to the BDEC
Acquisition;  (f) the  sale by PMOI of its  ownership  interests  in  Prime/BDEC
Acquisition,  L.L.C. (or all of Prime/BDEC Acquisition,  L.L.C.'s assets) on the
dates  and  for the  purchase  price  required  by the  Contribution  Agreement,
provided that such tangible  assets are replaced by assets of similar  character
where  the  replacement  of such  asset  is  necessary  or  appropriate  for the
continued  conduct of such Company's  business as presently  conducted,  and (g)
transfers by Borrower or by any Subsidiary of interests in Partnerships, so long
as the aggregate  EBITDA  Transfer for all Restricted  Transfers does not exceed
the lesser of : (a) ten percent (10%) of Borrower's EBITDA for the most recently
ended four fiscal quarters,  and (b) $6,500,000 and included within such amount,
the aggregate EBITDA Transfer for all Restricted LASIK Transfers does not exceed
the  lesser  of:  (a) ten  percent  (10%) of the  EBITDA of Prime  RVC,  and (b)
$2,000,000.  "EBITDA Transfer" with respect to any Partnership  interests in any
Partnership  transferred  by Borrower or any  Subsidiary  shall equal the EBITDA
generated by such Partnership  interests for the last four fiscal quarters prior
to the date of such  transfer of each such  Partnership  interest.  A Restricted
Transfer  shall be any transfer or series of related  transfers  of  Partnership
interests in any one  Partnership  by Borrower or any  Subsidiary  in any 90 day
period,  in which the EBITDA Transfer equals or exceeds  $250,000.  A Restricted
LASIK  Transfer  shall  be any  transfer  or  series  of  related  transfers  of
Partnership  interests  by Prime  RVC or any of its  Subsidiaries  in which  the
EBITDA  Transfer  equals  or  exceeds  $250,000.  In the  case of any  transfers
pursuant to paragraph (g), after giving effect to such transfers, a Company must
Control such  Partnership.  Administrative  Agent is  authorized  to release any
liens on such Partnership interests transferred pursuant to this Section 9.8, as
further set forth in Section 5.3.

         Section  9.9 Sale and  Leaseback.  Borrower  will not enter  into,  nor
permit any of its Subsidiaries  (other than the Partnerships) to enter into, any
arrangement  with any Person (other than another  Company)  pursuant to which it
leases from such Person  equipment used in lithotripsy  operations that has been
or is to be sold or transferred,  directly or indirectly,  by it to such Person;
provided,  however,  that the Companies may enter into any arrangement  with any
Person  pursuant to which it leases  from such Person real or personal  property
not  used  in  lithotripsy  operations  that  has  been  or  is to  be  sold  or
transferred,  directly or  indirectly,  by it to such  Person,  in an  aggregate
amount of up to but not to exceed $500,000.00 during the term of this Agreement.

         Section 9.10 Prepayment of Debt.  Borrower will not prepay,  nor permit
any of its Subsidiaries to prepay,  any Debt except the  Obligations,  or redeem
the Senior Subordinated Notes other than a redemption of a portion of the Senior
Subordinated  Notes  pursuant  to  Section  3.07  of  the  Senior   Subordinated
Indenture,  so long as after  giving  effect  thereto,  no  Default  or Event of
Default would exist.

         Section 9.11 Nature of Business. Borrower will not, and will not permit
any of its Subsidiaries (other than the Partnerships) to, engage in any business
other  than the  businesses  in which  they are  engaged  on the date  hereof or
businesses  which  are  reasonably  related  thereto;  provided,  however,  that
Borrower  will not and will not permit any of its  Subsidiaries  (other than the
Partnerships)  not already in the business of providing  non-medical  management
services to cardiac  rehabilitation or diagnostic imaging operations,  to engage
in either such business.

         Section 9.12 Environmental Protection.  Borrower will not, and will not
permit any of its  Subsidiaries  to,  conduct  any  activity or use any of their
respective  properties or assets in any manner that could reasonably be expected
to violate any  Environmental  Law or create any  Environmental  Liabilities for
which Borrower or any of its Subsidiaries would be responsible.

         Section 9.13 Accounting.  Borrower will not, and will not permit any of
its  Subsidiaries  (other than the  Partnerships)  to, change its fiscal year or
make any change (a) in accounting  treatment or reporting  practices,  except as
permitted  by GAAP and  disclosed  to the  Administrative  Agent,  or (b) in tax
reporting treatment, except as permitted by law.

         Section  9.14  Amendment  of  Partnership  and  Management  Agreements.
Borrower  will not,  and will not permit any of its  Subsidiaries  to, amend any
partnership agreements,  regulations,  or articles of any of the Partnerships or
any management  agreements  between any Company and any of the Partnerships,  if
such amendment could reasonably be expected to have a material adverse effect on
the business,  condition (financial or otherwise),  operations, or properties of
the Companies taken as a whole, Borrower, or any Material Subsidiary.

         Section 9.15      Financial Hedges.

         (a) To the extent any Lender or its Affiliate  issues a Financial Hedge
to any  Company,  such Lender or its  Affiliate is afforded the benefits of (and
Borrower [or any Company by execution of Collateral Documents] hereby confirms a
grant  of)  Liens  in and to  the  Collateral  as  evidenced  by the  Collateral
Documents  to the  extent  of such  Lender's  (or  Affiliate  thereof's)  credit
exposure  under  such  Financial  Hedge;  such Lien is pari  passu  with that of
Administrative Agent on behalf of the Lenders.

<PAGE>

         (b)  Financial  Hedges  held  by any  Company  permitted  by  the  Loan
Documents,  shall be subject  to the  following:  (i) each such  Lender or other
institution  issuing a Financial  Hedge shall calculate its credit exposure in a
reasonable and customary manner; (ii) all documentation for such Financial Hedge
shall conform to ISDA standards and must be acceptable to  Administrative  Agent
with  respect  to  intercreditor  issues;  (iii) if issued by any  Lender or any
Affiliate  of a Lender to Borrower,  the credit  exposure  under such  Financial
Hedge shall be secured by Liens in and to the  Collateral  as  evidenced  by the
Collateral  Documents  on a pari passu  basis  with the Liens of  Administrative
Agent (held for the benefit of Lenders),  and such Lender or Affiliate issuing a
Financial  Hedge  shall,  by  acceptance  of the  benefits  of such Liens in the
Collateral  agree to the  provisions  of Section 12.6;  and (iv) such  Financial
Hedge shall be incurred in the ordinary  course of business and consistent  with
prior business practices of the Companies and not for speculative purposes.

         Section 9.16 Control of Prime Refractive, L.L.C. Borrower or one of its
Wholly-Owned  Subsidiaries must own at least 51% of the membership  interests in
and Control Prime Refractive, L.L.C.

                        ARTICLE X -- FINANCIAL COVENANTS

         Borrower  hereby  covenants and agrees that, as long as the Obligations
or any part thereof are outstanding or any Lender has any Commitment  hereunder,
Borrower will perform and observe the following financial covenants:

         Section 10.1 Total Net Funded Debt to EBITDA.  Borrower will not permit
the Total Net Funded Debt to EBITDA Ratio, determined as of the last day of each
fiscal  quarter of the Companies and for the four (4) fiscal quarter period then
ending, to exceed the ratio set forth opposite such period below:

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

                                  Period Ratio

------------------------------------------------- ------------------------------
------------------------------------------------- ------------------------------

January 1, 1998 through December 31, 2000                    3.50 to 1.0
------------------------------------------------- ------------------------------
------------------------------------------------- ------------------------------

------------------------------------------------- ------------------------------
------------------------------------------------- ------------------------------

January 1, 2002 and thereafter                               3.00 to 1.0
================================================= ==============================

         Section 10.2 Senior Net Funded Debt To EBITDA Ratio.  Borrower will not
permit the Senior  Net  Funded  Debt to EBITDA  Ratio as of the last day of each
fiscal  quarter of  Borrower to exceed the ratio set forth  opposite  such dates
below:

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

                                  Period Ratio

------------------------------------------------- ------------------------------
------------------------------------------------- ------------------------------

January 1, 1998 through December 31, 2000                     2.50 to 1.0
------------------------------------------------- ------------------------------
------------------------------------------------- ------------------------------

------------------------------------------------- ------------------------------
------------------------------------------------- ------------------------------

January 1, 2002 and thereafter                                2.00 to 1.0
================================================= ==============================

         Section 10.3 Debt Service Coverage Ratio.  Borrower will not permit the
Debt  Service  Coverage  Ratio  as of the  last day of each  fiscal  quarter  of
Borrower to be less than the ratio set forth opposite such dates below:

<PAGE>

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

                                  Period Ratio

------------------------------------------------- ------------------------------
------------------------------------------------- ------------------------------

January 1, 1998 through December 31, 2000                       1.50 to 1.0
------------------------------------------------- ------------------------------
------------------------------------------------- ------------------------------

------------------------------------------------- ------------------------------
------------------------------------------------- ------------------------------

January 1, 2002 and thereafter                                  1.75 to 1.0
================================================= ==============================

         Section 10.4  Consolidated Net Worth.  Borrower shall not permit, as of
the last day of each fiscal quarter of Borrower,  its  Consolidated Net Worth to
be less than $86,005,000,  such amount to be increased beginning with the fiscal
quarter ending December 31, 1999, and on the last day of each successive  fiscal
quarter of Borrower  by an amount  equal to one  hundred  percent  (100%) of the
increase in net worth arising from any  Acquisition  or equity  issuance  during
such fiscal  quarter,  (b) increased on December 31, 1999 and on the last day of
each successive  fiscal quarter of Borrower,  by an amount equal to seventy-five
percent (75%) of positive  Consolidated Net Income for such fiscal quarter;  and
(c)  decreased  on any date after  September  30,  1999 by the amount of capital
stock of Borrower  repurchased  or retired by Borrower  or any  Subsidiary,  not
exceeding $11,993,000 in the aggregate.

                              ARTICLE XI -- DEFAULT

     Section 11.1 Events of Default.  Each of the  following  shall be deemed an
"Event  of  Default":

     (a) Borrower  shall fail to pay when due any amount of principal  under any
Note.

         (b)  Borrower  shall  fail to pay to the  Administrative  Agent  or any
Lender (through the  Administrative  Agent),  any interest on the Advances,  any
fees due  hereunder or under any other Loan  Document,  or any other part of the
Obligations  which  does not  constitute  principal  under the  Notes,  and such
failure  shall  continue for three (3) Business  Days after such payment  became
due.

         (c) Any  representation  or warranty made or deemed made by Borrower or
any Obligated Party (or any of their  respective  officers) in any Loan Document
or in any certificate,  report,  notice, or financial statement furnished at any
time in connection with this Agreement shall be false, misleading,  or erroneous
in any  material  respect  when made or deemed to have been made and the  effect
thereof  shall not have been cured  within ten (10)  Business  Days after notice
thereof to  Borrower  by the  Administrative  Agent or any Lender  (through  the
Administrative Agent).

         (d)  Borrower  shall  fail to  perform,  observe,  or  comply  with any
covenant,  agreement,  or  term  contained  in  Article  X; or  Borrower  or any
Obligated  Party shall fail to perform,  observe,  or comply with any  covenant,
agreement or term  contained in Section 8.1 (a),  (b), (c) or (d), or Article IX
and such failure  shall  continue for a period of three (3) Business  Days after
notice thereof to Borrower by the  Administrative  Agent or any Lender  (through
the  Administrative  Agent);  or Borrower or any  Obligated  Party shall fail to
perform, observe br comply with any other covenant, agreement, or term contained
in this  Agreement or any other Loan Document  (other than  covenants to pay the
Obligations)  and such failure shall  continue for a period of ten (10) Business
Days after notice thereof to Borrower by the Administrative  Agent or any Lender
(through the Administrative Agent).

<PAGE>

         (e)  Any  Company  shall  commence  a  voluntary   proceeding   seeking
liquidation, reorganization, or other relief with respect to itself or its debts
under any  bankruptcy,  insolvency,  or other  similar law now or  hereafter  in
effect or seeking the appointment of a trustee, receiver, liquidator, custodian,
or other similar  official of it or a substantial  part of its property or shall
consent to any such relief or to the appointment of or taking  possession by any
such official in an involuntary case or other proceeding commenced against it or
shall make a general  assignment for the benefit of creditors or shall generally
fail to pay its debts as they become due or shall take any  corporate  action to
authorize any of the foregoing.

         (f) An involuntary  proceeding  shall be commenced  against any Company
seeking liquidation,  reorganization,  or other relief with respect to it or its
debts under any bankruptcy, insolvency, or other similar law now or hereafter in
effect or seeking the appointment of a trustee, receiver, liquidator,  custodian
or other  similar  official for it or a substantial  part of its  property,  and
either such involuntary  proceeding shall remain  undismissed and unstayed for a
period of forty-five (45) days or an order for relief is entered.

         (g) Any Company  shall fail to discharge  within a period of forty-five
(45) days after the  commencement  thereof  any  attachment,  sequestration,  or
similar  proceeding or proceedings,  including  without  limitation any order of
forfeiture,  seizure or divestiture  (whether under RICO or otherwise) involving
an  aggregate  amount in excess of Five  Hundred  Thousand  and  00/100  Dollars
($500,000.00) against any of its assets or properties.

         (h) A final judgment or judgments for the payment of money in excess of
Five Hundred Thousand and 00/100 Dollars ($500,000.00) in the aggregate shall be
rendered  by a court or courts  against  any  Company  and the same shall not be
discharged  (or provision  shall not be made for such  discharge),  or a stay of
execution  thereof shall not be procured,  within  forty-five (45) days from the
date of entry  thereof  and such  Company  shall  not,  within  said  period  of
forty-five  (45) days, or such longer period during which  execution of the same
shall have been stayed,  appeal therefrom and cause the execution  thereof to be
stayed during such appeal.

         (i) Any Company shall fail to pay when due any principal of or interest
on the  Senior  Subordinated  Notes or on any  other  Debt  (including,  without
limitation,  the Advancing  Term Facility) in an aggregate  principal  amount of
Five Hundred  Thousand and 00/100 Dollars  ($500,000.00) or more (other than the
Obligations),  or the maturity of the Senior Subordinated Notes or any such Debt
shall  have been  accelerated,  or the  Senior  Subordinated  Notes  (except  in
connection  with the exchange  thereof for the Exchange  Notes) or any such Debt
shall have been required to be prepaid prior to the stated maturity thereof,  or
any event shall have occurred that permits (or, with the giving of notice or the
lapse of time or both,  would  permit)  any  holder  or  holders  of the  Senior
Subordinated Notes or such Debt or any Person acting on behalf of such holder or
holders to accelerate the maturity thereof or require any such prepayment.

         (j) This Agreement or any other Loan Document shall cease to be in full
force  and  effect  or  shall be  declared  null  and  void or the  validity  or
enforceability  thereof  shall be  contested  or  challenged  by  Borrower,  any
Subsidiary  of  Borrower,  any  Obligated  Party  or  any  of  their  respective
shareholders,  or  Borrower  or any  Obligated  Party shall deny that it has any
further liability or obligation under any of the Loan Documents,  or any Lien or
security interest created by the Loan Documents shall for any reason cease to be
a valid,  first priority perfected security interest in and Lien upon any of the
Collateral purported to be covered thereby.

<PAGE>

         (k) Any of the  following  events  shall occur or exist with respect to
Borrower or any ERISA Affiliate:  (i) any Prohibited  Transaction  involving any
Plan; (ii) any Reportable Event with respect to any Plan; (iii) the filing under
Section  4041 of  ERISA of a  notice  of  intent  to  terminate  any Plan or the
termination of any Plan;  (iv) any event or circumstance  that might  constitute
grounds entitling the PBGC to institute  proceedings under Section 4042 of ERISA
for the termination  of, or for the appointment of a trustee to administer,  any
Plan, or the institution by the PBGC of any such proceedings; or (v) complete or
partial  withdrawal  under  Section 4201 or 4204 of ERISA from a  Multi-employer
Plan or the  reorganization,  insolvency,  or termination of any  Multi-employer
Plan; and in each case above,  such event or condition,  together with all other
events or conditions,  if any, have subjected or could in the reasonable opinion
of the Required Lenders subject  Borrower,  or any of its  Subsidiaries,  to any
tax, penalty, or other liability to a Plan, a Multi-employer  Plan, the PBGC, or
otherwise (or any  combination  thereof) which in the aggregate  exceed or could
reasonably  be expected  to exceed  Five  Hundred  Thousand  and 00/100  Dollars
($500,000.00).

         (l)      Any Change in Control shall occur.

         Section  11.2  Remedies.  If any Event of  Default  shall  occur and be
continuing,  the  Administrative  Agent  may (and if  directed  by the  Required
Lenders, shall) do any one or more of the following:

                  (a)  Acceleration.  Declare all  outstanding  principal of and
         accrued and unpaid  interest on the Notes and all other  obligations of
         Borrower under the Loan Documents  immediately due and payable, and the
         same  shall  thereupon  become  immediately  due and  payable,  without
         notice,   demand,   presentment,   notice   of   dishonor,   notice  of
         acceleration,  notice  of  intent  to  accelerate,  protest,  or  other
         formalities  of any kind, all of which are hereby  expressly  waived by
         Borrower;

               (b) Termination of Commitments. Terminate the Commitments without
          notice to Borrower;

               (c) Judgment. Reduce any claim to judgment;

               (d) Foreclosure.  Foreclose or otherwise enforce any Lien granted
          to the Administrative  Agent for the benefit of itself and the Lenders
          to secure  payment and  performance  of the  Obligations in accordance
          with the terms of the Loan Documents; and

               (e) Rights.  Exercise any and all rights and remedies afforded by
          the laws of the  State of Texas or any other  jurisdiction,  by any of
          the Loan Documents, by equity, or otherwise;

provided,  however,  that  upon the  occurrence  of an Event  of  Default  under
subsection  (e) or (f) of Section 11.1,  the  Commitments  of all of the Lenders
shall automatically  terminate, and the outstanding principal of and accrued and
unpaid  interest on the Notes and all other  obligations  of Borrower  under the
Loan  Documents  shall  thereupon  become  immediately  due and payable  without
notice, demand, presentment, notice of dishonor, notice of acceleration,  notice
of intent to accelerate, protest, or other formalities of any kind, all of which
are hereby expressly waived by Borrower.

         Section 11.3 Performance by the Administrative Agent. If Borrower shall
fail to perform any covenant or agreement  in  accordance  with the terms of the
Loan Documents,  the Administrative  Agent may, at the direction of the Required
Lenders,  perform or attempt to perform such  covenant or agreement on behalf of
Borrower.  In such event,  Borrower shall, at the request of the  Administrative
Agent,  promptly  pay any amount  expended  by the  Administrative  Agent or the
Lenders in connection  with such  performance  or attempted  performance  to the
Administrative Agent at the Principal Office,  together with interest thereon at
the  Default  Rate  from  and  including  the  date of such  expenditure  to but
excluding  the  date  such  expenditure  is paid in  full.  Notwithstanding  the
foregoing,  it is expressly agreed that neither the Administrative Agent nor any
Lender shall have any liability or  responsibility  for the  performance  of any
obligation of Borrower under this Agreement or any of the other Loan Documents.

<PAGE>

                     ARTICLE XII -- THE ADMINISTRATIVE AGENT

         Section 12.1 Appointment,  Powers and Immunities.  In order to expedite
the various  transactions  contemplated  by this  agreement,  the Lenders hereby
irrevocably appoint and authorize Bank of America to act as their Administrative
Agent  hereunder  and under  each of the other Loan  Documents.  Bank of America
consents  to  such   appointment  and  agrees  to  perform  the  duties  of  the
Administrative  Agent as specified herein.  The Lenders authorize and direct the
Administrative Agent to take such action in their name and on their behalf under
the terms and  provisions of the Loan  Documents and to exercise such rights and
powers  thereunder  as  are  specifically   delegated  to  or  required  of  the
Administrative  Agent for the Lenders,  together  with such rights and powers as
are reasonably  incidental thereto. The Administrative Agent is hereby expressly
authorized to act as the Administrative  Agent on behalf of itself and the other
Lenders:

                  (a) To receive on behalf of each of the Lenders any payment of
         principal,  interest,  fees or  other  amounts  paid  pursuant  to this
         Agreement  and the Notes and to  distribute to each Lender its pro rata
         share of all payments so received as provided in this Agreement;

               (b) To receive all documents and items to be furnished  under the
          Loan Documents;

               (c) To act as  nominee  for and on behalf of the  Lenders  in and
          under the Loan Documents;

               (d) To arrange for the means whereby the funds of the Lenders are
          to be made available to Borrower;

                  (e)  To  distribute  to  the  Lenders  information,  requests,
         notices, payments, prepayments, documents and other items received from
         Borrower, the other Obligated Parties, and other Persons;

                  (f) To execute and deliver to  Borrower,  the other  Obligated
         Parties, and other Persons, all requests, demands, approvals,  notices,
         and consents received from the Lenders;

               (g) To the extent permitted by the Loan Documents, to exercise on
          behalf of each Lender all rights and  remedies of the Lenders upon the
          occurrence of any Event of Default;

                  (h) To accept,  execute,  and  deliver the  Borrower  Security
         Agreement,  the Guarantor Security  Agreements,  the Pledge Agreements,
         and any other security documents as the secured party; and

               (i) To  take  such  other  actions  as may  be  requested  by the
          Required Lenders.

<PAGE>

         Neither the Administrative  Agent nor any of its Affiliates,  officers,
directors, employees, attorneys, or agents shall be liable to any Lender for any
action  taken or omitted to be taken by any of them  hereunder  or  otherwise in
connection with this Agreement or any of the other Loan Documents (INCLUDING ANY
ACTION TAKEN OR OMITTED TO BE TAKEN BY SUCH PARTIES NEGLIGENTLY),  but excluding
such actions or omissions  arising from such  parties' own gross  negligence  or
willful  misconduct.  Without limiting the generality of the preceding sentence,
the  Administrative  Agent:  (i) may treat  the payee of any Note as the  holder
thereof until the Administrative Agent receives written notice of the assignment
or  transfer  thereof  signed  by such  payee  and in form  satisfactory  to the
Administrative Agent; (ii) shall have no duties or responsibilities except those
expressly set forth in this  Agreement and the other Loan  Documents,  and shall
not by reason of this  Agreement  or any other  Loan  Document  be a trustee  or
fiduciary for any Lender; (iii) shall not be required to initiate any litigation
or collection  proceedings  hereunder or under any other Loan Document except to
the extent requested by the Required  Lenders;  (iv) shall not be responsible to
the  Lenders  for  any  recitals,  statements,   representations  or  warranties
contained in this  Agreement or any other Loan Document,  or any  certificate or
other document referred to or provided for in, or received by any of them under,
this  Agreement  or any  other  Loan  Document,  or  for  the  value,  validity,
effectiveness,  enforceability,  or  sufficiency  of this Agreement or any other
Loan  Document  or any other  document  referred  to or  provided  for herein or
therein  or for any  failure by any  Person to  perform  any of its  obligations
hereunder or thereunder;  (v) may consult with legal counsel  (including counsel
for Borrower),  independent public accountants, and other experts selected by it
and shall not be liable  for any  action  taken or  omitted  to be taken in good
faith by it in  accordance  with the  advice of such  counsel,  accountants,  or
experts;  and (vi)  shall  incur no  liability  under or in  respect of any Loan
Document by acting upon any notice, consent, certificate, or other instrument or
writing  believed by it to be genuine and signed or sent by the proper  party or
parties.  As to any matters not expressly  provided for by this  Agreement,  the
Administrative  Agent  shall in all cases be fully  protected  in acting,  or in
refraining from acting, here under in accordance with instructions signed by the
Required  Lenders,  and such instructions of the Required Lenders and any action
taken or failure to act pursuant thereto shall be binding on all of the Lenders;
provided,  however,  that the Administrative Agent shall not be required to take
any action which exposes the Administrative Agent to personal liability or which
is contrary to this Agreement or any other Loan Document or applicable law.

         Section 12.2 Rights of Administrative  Agent as a Lender.  With respect
to its  Commitment,  the Advances  made by it and the Note issued to it, Bank of
America in its  capacity  as a Lender  hereunder  shall have the same rights and
powers hereunder as any other Lender and may exercise the same as though it were
not acting as the  Administrative  Agent,  and the term  "Lender"  or  "Lenders"
shall, unless the context otherwise indicates,  include the Administrative Agent
in its  individual  capacity.  The  Administrative  Agent and its Affiliates may
(without  having to account  therefor to any Lender) accept  deposits from, lend
money to, act as trustee under  indentures of, provide merchant banking services
to, and generally  engage in any kind of business with Borrower,  any Subsidiary
of Borrower, any other Obligated Party, and any other Person who may do business
with or own securities of Borrower or any other  Obligated  Party,  all as if it
were not  acting as the  Administrative  Agent and  without  any duty to account
therefor to the Lenders.

         Section 12.3  Sharing of Payments,  Etc. If any Lender shall obtain any
payment of any  principal  of or interest  on any Advance  made by it under this
Agreement or payment of any other  obligation under the Loan Documents then owed
by Borrower or any other  Obligated  Party to such  Lender,  whether  voluntary,
involuntary,  through  the  exercise  of any  right of  setoff,  lender's  lien,
counterclaim  or similar right,  or otherwise,  in excess of its pro rata share,
such Lender shall promptly purchase from the other Lenders participations in the
Advances held by them hereunder in such amounts, and make such other adjustments
from time to time as shall be necessary to cause such purchasing Lender to share
the excess payment ratably with each of the other Lenders in accordance with its
pro rata portion thereof. To such end, all of the Lenders shall make appropriate
adjustments among themselves (by the resale of participations sold or otherwise)
if all or any portion of such excess  payment is  thereafter  rescinded  or must
otherwise be restored. Borrower agrees, to the fullest extent it may effectively
do so under applicable law, that any Lender so purchasing a participation in the
Advances made by the other  Lenders may exercise all rights of setoff,  lender's
lien,  counterclaim,  or similar  rights with respect to such  participation  as
fully as if such  Lender  were a direct  holder of  Advances  to Borrower in the
amount of such participation.  Nothing contained herein shall require any Lender
to exercise  any such right or shall affect the right of any Lender to exercise,
and retain the benefits of exercising,  any such right with respect to any other
indebtedness or obligation of Borrower.

<PAGE>

         Section 12.4 Indemnification. THE LENDERS HEREBY AGREE TO INDEMNIFY THE
AGENTS FROM AND HOLD THE AGENTS  HARMLESS  AGAINST (TO THE EXTENT NOT REIMBURSED
UNDER SECTIONS 13.1 AND 13.2, BUT WITHOUT  LIMITING THE  OBLIGATIONS OF BORROWER
UNDER  SECTIONS  13.1 AND 13.2),  RATABLY IN  ACCORDANCE  WITH THEIR  RESPECTIVE
COMMITMENTS, ANY AND ALL LIABILITIES,  OBLIGATIONS,  LOSSES, DAMAGES, PENALTIES,
ACTIONS, JUDGMENTS,  DEFICIENCIES,  SUITS, COSTS, EXPENSES (INCLUDING ATTORNEYS'
FEES), AND  DISBURSEMENTS OF ANY KIND OR NATURE  WHATSOEVER WHICH MAY BE IMPOSED
ON, INCURRED BY, OR ASSERTED AGAINST ANY AGENT IN ANY WAY RELATING TO OR ARISING
OUT OF ANY OF THE LOAN  DOCUMENTS  OR ANY ACTION TAKEN OR OMITTED TO BE TAKEN BY
ANY AGENT UNDER OR IN RESPECT OF ANY OF THE LOAN DOCUMENTS INCLUDING ANY PORTION
OF THE  FOREGOING TO THE EXTENT  CAUSED BY THE ANY AGENT'S SOLE OR  CONTRIBUTORY
NEGLIGENCE; PROVIDED, FURTHER, THAT NO LENDER SHALL BE LIABLE FOR ANY PORTION OF
THE FOREGOING TO THE EXTENT  CAUSED BY ANY AGENT'S  GROSS  NEGLIGENCE OR WILLFUL
MISCONDUCT.  WITHOUT LIMITATION OF THE FOREGOING, IT IS THE EXPRESS INTENTION OF
THE  LENDERS  THAT THE  AGENTS  SHALL  BE  INDEMNIFIED  HEREUNDER  FROM AND HELD
HARMLESS  AGAINST  ALL  OF  SUCH  LIABILITIES,   OBLIGATIONS,  LOSSES,  DAMAGES,
PENALTIES, ACTIONS, JUDGMENTS,  DEFICIENCIES,  SUITS, COSTS, EXPENSES (INCLUDING
ATTORNEYS' FEES), AND DISBURSEMENTS OF ANY KIND OR NATURE DIRECTLY OR INDIRECTLY
ARISING OUT OF OR  RESULTING  FROM THE SOLE OR  CONTRIBUTORY  NEGLIGENCE  OF THE
AGENTS. WITHOUT LIMITING ANY OTHER PROVISION OF THIS SECTION, EACH LENDER AGREES
TO REIMBURSE EACH AGENT PROMPTLY UPON DEMAND FOR ITS PRO RATA SHARE  (CALCULATED
ON THE  BASIS  OF  THE  COMMITMENTS)  OF  ANY  AND  ALL  OUT-OF-POCKET  EXPENSES
(INCLUDING  ATTORNEYS'  FEES)  INCURRED  BY THE  AGENTS IN  CONNECTION  WITH THE
PREPARATION,  EXECUTION, DELIVERY,  ADMINISTRATION,  MODIFICATION,  AMENDMENT OR
ENFORCEMENT (WHETHER THROUGH NEGOTIATIONS,  LEGAL PROCEEDINGS, OR OTHERWISE) OF,
OR LEGAL  ADVICE  IN  RESPECT  OF  RIGHTS OR  RESPONSIBILITIES  UNDER,  THE LOAN
DOCUMENTS,  TO THE EXTENT THAT SUCH AGENT IS NOT REIMBURSED FOR SUCH EXPENSES BY
BORROWER.

         Section 12.5 Independent  Credit Decisions.  Each Lender agrees that it
has  independently  and without  reliance on any Agent or any other Lender,  and
based on such documents and information as it has deemed  appropriate,  made its
own credit  analysis of Borrower and decision to enter into this  Agreement  and
that it will,  independently  and without  reliance  upon any Agent or any other
Lender,  and  based  upon  such  documents  and  information  as it  shall  deem
appropriate  at the time,  continue to make its own  analysis  and  decisions in
taking or not  taking  action  under  this  Agreement  or any of the other  Loan
Documents.  The  Administrative  Agent  shall  not be  required  to keep  itself
informed as to the  performance or observance by Borrower or any Obligated Party
of this  Agreement or any other Loan  Document or to inspect the  properties  or
books of Borrower or any Obligated Party. Except for notices,  reports and other
documents and information  expressly  required to be furnished to the Lenders by
the  Administrative  Agent  hereunder  or under the other  Loan  Documents,  the
Administrative  Agent shall not have any duty or  responsibility  to provide any
Lender with any credit or other  financial  information  concerning the affairs,
financial  condition or business of Borrower or any  Obligated  Party (or any of
their Affiliates) which may come into the possession of the Administrative Agent
or any of its Affiliates.

<PAGE>

         Section 12.6 Several Commitments. The Commitments and other obligations
of the Lenders under this  Agreement  are several.  The default by any Lender in
making an Advance in accordance with its Commitment  shall not relieve the other
Lenders of their obligations  under this Agreement.  In the event of any default
by any  Lender  in  making  any  Advance,  each  nondefaulting  Lender  shall be
obligated  to make its Advance but shall not be  obligated to advance the amount
which the defaulting Lender was required to advance hereunder. In no event shall
any  Lender be  required  to advance  an amount or  amounts  which  shall in the
aggregate  exceed such Lender's  Commitment.  No Lender shall be responsible for
any act or omission of any other Lender.

         Section 12.7 Successor Administrative Agent. Subject to the appointment
and  acceptance  of a  successor  Administrative  Agent as provided  below,  the
Administrative  Agent may  resign at any time by giving  notice  thereof  to the
Lenders and  Borrower  and the  Administrative  Agent may be removed at any time
with or without  cause by the Required  Lenders.  Upon any such  resignation  or
removal,  the  Required  Lenders  will  have the right to  appoint  a  successor
Administrative   Agent  from  among  the  remaining  Lenders.  If  no  successor
Administrative  Agent shall have been so appointed  by the Required  Lenders and
shall have accepted such appointment  within thirty (30) days after the retiring
Administrative  Agent's giving of notice of resignation or the Required Lenders'
removal of the retiring  Administrative Agent, then the retiring  Administrative
Agent may, on behalf of the Lenders,  appoint a successor  Administrative Agent,
which shall be a commercial  bank organized  under the laws of the United States
of America or any State  thereof and having  combined  capital and surplus of at
least  One  Billion  Dollars  ($1,000,000,000).   Upon  the  acceptance  of  its
appointment as successor  Administrative  Agent,  such successor  Administrative
Agent shall  thereupon  succeed to and become  vested  with all rights,  powers,
privileges,  immunities,  and duties of the resigning or removed  Administrative
Agent,  and the  resigning or removed  Administrative  Agent shall be discharged
from its  duties  and  obligations  under  this  Agreement  and the  other  Loan
Documents.   After  any  Administrative   Agent's   resignation  or  removal  as
Administrative  Agent,  the  provisions  of this  Article XII shall  continue in
effect for its benefit in respect of any actions taken or omitted to be taken by
it while it was the Administrative Agent.

         Section 12.8      Independent Contractor.

         (a) The relationship between each Agent and each of the Lenders is that
of an  independent  contractor.  The use of the term "Agent" is for  convenience
only  and  is  used  to  describe,  as a form  of  convention,  the  independent
contractual  relationship  between each Agent and each of the  Lenders.  Nothing
contained in this  Agreement or the other Loan  Documents  shall be construed to
create an agency,  trust or other fiduciary  relationship  between any Agent and
any of the Lenders.

         (b) As an independent  contractor  empowered by the Lenders to exercise
certain  rights and perform  certain duties and  responsibilities  hereunder and
under the other Loan  Documents,  the  Administrative  Agent is  nevertheless  a
"representative"  of the  Lenders,  as that term is  defined in Article 1 of the
Uniform  Commercial Code, for purposes of actions for the benefit of the Lenders
and the  Administrative  Agent  with  respect  to all  collateral  security  and
guaranties  contemplated  by  the  Loan  Documents.  Such  actions  include  the
designation of the Administration  Agent as "secured party,"  "mortgagee" or the
like on all financing  statements and other documents and  instruments,  whether
recorded or  otherwise,  relating  to the  attachment,  perfection,  priority or
enforcement of any security interests, mortgages or deeds of trust in collateral
security   intended  to  secure  the  payment  or  performance  of  any  of  the
Obligations, all for the benefit of the Lenders and the Administrative Agent.

<PAGE>

                          ARTICLE XIII -- MISCELLANEOUS

         Section 13.1 Expenses. Borrower hereby agrees to pay on demand: (a) all
reasonable  costs and expenses of the Agents in connection with the preparation,
negotiation,  syndication,  execution,  and delivery of this  Agreement  and the
other  Loan  Documents  including,   without  limitation,  the  legal  fees  and
reasonable  expenses of legal counsel for the Agents;  (b) all reasonable  costs
and  expenses  of  the  Agents  in  connection  with  any  and  all  amendments,
modifications,   renewals,  extensions  and  supplements  of  any  of  the  Loan
Documents;  (c) all reasonable  costs and expenses of the Agents and the Lenders
in connection with any Default, including any work-outs,  amendments to any Loan
Documents,  or  negotiations  related  thereto,  and  the  enforcement  of  this
Agreement or any other Loan Document,  including,  without limitation,  the fees
and expenses of legal counsel and  professional  advisors for the Agents and the
Lenders;  (d)  all  transfer,  stamp,  documentary,   or  other  similar  taxes,
assessments,  or charges levied by any Governmental Authority in respect of this
Agreement  or any  of  the  other  Loan  Documents;  (e)  all  costs,  expenses,
assessments,   and  other  charges  incurred  in  connection  with  any  filing,
registration,  recording,  or  perfection  of  any  security  interest  or  Lien
contemplated  by this  Agreement or any other Loan  Document;  and (f) all other
reasonable  costs and expenses  incurred by the Agents in  connection  with this
Agreement or any other Loan Document,  including, without limitation, all costs,
expenses,  and other charges incurred in connection with obtaining any mortgagee
title insurance policy,  survey, audit,  appraisal in respect of the Collateral,
and other out-of-pocket costs and expenses.

         Section 13.2  Indemnification.  BORROWER SHALL INDEMNIFY THE AGENTS AND
EACH LENDER AND EACH AFFILIATE THEREOF AND THEIR RESPECTIVE OFFICERS, DIRECTORS,
EMPLOYEES,  ATTORNEYS,  AND AGENTS FROM, AND HOLD EACH OF THEM HARMLESS AGAINST,
ANY  AND  ALL  LOSSES,  LIABILITIES,   CLAIMS,  DAMAGES,  PENALTIES,  JUDGMENTS,
DISBURSEMENTS,  COSTS, AND EXPENSES  (INCLUDING  REASONABLE  ATTORNEYS' FEES) TO
WHICH ANY OF THEM MAY BECOME SUBJECT WHICH DIRECTLY OR INDIRECTLY  ARISE FROM OR
RELATE TO (A) THE NEGOTIATION, EXECUTION, DELIVERY, PERFORMANCE, ADMINISTRATION,
OR  ENFORCEMENT  OF ANY OF  THE  LOAN  DOCUMENTS,  (B)  ANY OF THE  TRANSACTIONS
CONTEMPLATED  BY  THE  LOAN  DOCUMENTS,  (C)  ANY  BREACH  BY  BORROWER  OF  ANY
REPRESENTATION,  WARRANTY,  COVENANT, OR OTHER AGREEMENT CONTAINED IN ANY OF THE
LOAN  DOCUMENTS,  (D)  THE  PRESENCE,  RELEASE,  THREATENED  RELEASE,  DISPOSAL,
REMOVAL,  OR CLEANUP OF ANY HAZARDOUS  MATERIAL  LOCATED ON, ABOUT,  WITHIN,  OR
AFFECTING  ANY OF THE  PROPERTIES  OR ASSETS OF  BORROWER OR ANY  SUBSIDIARY  OF
BORROWER, OR (E) ANY INVESTIGATION,  LITIGATION, OR OTHER PROCEEDING, INCLUDING,
WITHOUT  LIMITATION,   ANY  THREATENED   INVESTIGATION,   LITIGATION,  OR  OTHER
PROCEEDING  RELATING TO ANY OF THE  FOREGOING.  WITHOUT  LIMITING THE FOREGOING,
THIS INDEMNITY SHALL APPLY TO ANY LOSS, LIABILITY,  OBLIGATION, DAMAGE, PENALTY,
JUDGMENT,  CLAIM,  DEFICIENCY  OR EXPENSE  ARISING OUT OF THE SOLE OR CONCURRENT
NEGLIGENCE  OF ANY AGENT OR ANY  LENDER,  BUT AS TO ANY  AGENT OR  LENDER  SHALL
EXCLUDE ANY LOSS,  LIABILITY,  OBLIGATION,  DAMAGE,  PENALTY,  JUDGMENT,  CLAIM,
DEFICIENCY  OR  EXPENSE  ARISING  BY REASON OF THE GROSS  NEGLIGENCE  OR WILLFUL
MISCONDUCT OF SUCH AGENT OR LENDER.

<PAGE>

         Section 13.3 No Duty. All attorneys, accountants, appraisers, and other
professional  Persons  and  consultants  retained  by the Agents and the Lenders
shall have the right to act  exclusively  in the  interest of the Agents and the
Lenders and shall have no duty of disclosure,  duty of loyalty, duty of care, or
other duty or  obligation  of any type or nature  whatsoever  to  Borrower,  any
shareholder or Subsidiary of Borrower or any other Person.

         Section  13.4  No  Fiduciary  Relationship.  The  relationship  between
Borrower and each Lender is solely that of debtor and creditor,  and none of the
Agents nor any of the Lenders has any  fiduciary or other  special  relationship
with Borrower,  and no term or condition of any of the Loan  Documents  shall be
construed so as to deem the  relationship  between Borrower and any Lender to be
other than that of debtor and creditor.

         Section 13.5 No Waiver;  Cumulative Remedies. No failure on the part of
the Agents or any Lender to exercise and no delay in  exercising,  and no course
of dealing with respect to, any right,  power, or privilege under this Agreement
shall operate as a waiver thereof,  nor shall any single or partial  exercise of
any right,  power,  or  privilege  under this  Agreement  preclude  any other or
further  exercise  thereof  or  the  exercise  of any  other  right,  power,  or
privilege.  The rights and remedies provided for in this Agreement and the other
Loan  Documents  are  cumulative  and not  exclusive  of any rights and remedies
provided by law.

         Section 13.6      Successors and Assigns.

         (a) This  Agreement  shall be binding  upon and inure to the benefit of
the parties hereto and their respective successors and assigns. Borrower may not
assign or transfer any of its rights or obligations  hereunder without the prior
written consent of the Administrative  Agent and all of the Lenders.  Any Lender
may sell  participations to one or more banks or other institutions in or to all
or a portion of its rights and  obligations  under this  Agreement and the other
Loan  Documents  (including,  without  limitation,  all  or  a  portion  of  its
Commitments  and the Advances  owing to it);  provided,  however,  that (i) such
Lender's   obligations  under  this  Agreement  and  the  other  Loan  Documents
(including,  without limitation,  its Commitments) shall remain unchanged,  (ii)
such Lender shall remain solely  responsible to Borrower for the  performance of
such obligations, (iii) such Lender shall remain the holder of its Notes for all
purposes of this  Agreement,  (iv)  Borrower  shall  continue to deal solely and
directly  with  such  Lender  in  connection   with  such  Lender's  rights  and
obligations  under this  Agreement  and the other Loan  Documents,  and (v) such
Lender shall not sell a participation  that conveys to the participant the right
to vote or give or  withhold  consents  under this  Agreement  or any other Loan
Document,  other than the right to vote upon or consent to (A) any  increase  of
such Lender's  Commitments,  (B) any  reduction of the  principal  amount of, or
interest to be paid on, the  Advances of such Lender,  (C) any  reduction of any
commitment  fee or other amount  payable to such Lender under any Loan Document,
or (D) any  postponement  of any date for the  payment of any amount  payable in
respect of the Advances of such Lender.

<PAGE>

         (b)  Borrower  and  each of the  Lenders  agree  that  any  Lender  (an
"Assigning  Lender")  may at any time assign to one or more  Eligible  Assignees
all, or a portion of all, of its rights and obligations under this Agreement and
the other Loan  Documents  (including,  without  limitation,  its Commitment and
Advances) (each an "Assignee");  provided,  however, that (i) except in the case
of an  assignment  of  all of a  Lender's  rights  and  obligations  under  this
Agreement and the other Loan Documents,  or as otherwise  acceptable to Borrower
and the  Administrative  Agent the amount of the  Commitments  of the  assigning
Lender being assigned pursuant to each assignment  (determined as of the date of
the Assignment and Acceptance with respect to such assignment) shall in no event
be less than  $5,000,000.00,  and (ii) the parties to each such assignment shall
execute and deliver to the Administrative Agent for its acceptance and recording
in the Register (as defined below), an Assignment and Acceptance,  together with
the Note subject to such  assignment,  and a processing and  recordation  fee of
$3,500.00. Upon such execution,  delivery,  acceptance,  and recording, from and
after the effective date  specified in each  Assignment  and  Acceptance,  which
effective  date shall be at least  five (5)  Business  Days after the  execution
thereof,  or, if so specified in such  Assignment  and  Acceptance,  the date of
acceptance  thereof by the  Administrative  Agent,  (x) the assignee  thereunder
shall be a party  hereto as a  "Lender"  and,  to the  extent  that  rights  and
obligations  hereunder have been assigned to it pursuant to such  Assignment and
Acceptance,  have the rights and obligations of a Lender hereunder and under the
Loan Documents and (y) the Lender that is an assignor  thereunder  shall, to the
extent that rights and  obligations  hereunder have been assigned by it pursuant
to such  Assignment and  Acceptance,  relinquish its rights and be released from
its  obligations  under this Agreement and the other Loan Documents (and, in the
case of an Assignment and Acceptance  covering all or the remaining portion of a
Lender's  rights and  obligations  under the Loan  Documents,  such Lender shall
cease to be a party  thereto).  The  provisions  of Article IV and Section  13.2
shall continue with respect to such Assigning Lender.

         (c) By executing  and  delivering  an Assignment  and  Acceptance,  the
Assigning  Lender and its Assignee  confirm to and agree with each other and the
other parties hereto as follows:  (i) other than as provided in such  Assignment
and Acceptance,  such Assigning Lender makes no  representation  or warranty and
assumes  no  responsibility  with  respect  to any  statements,  warranties,  or
representations  made  in or in  connection  with  the  Loan  Documents  or  the
execution, legality, validity, and enforceability,  genuineness, sufficiency, or
value of the Loan  Documents  or any  other  instrument  or  document  furnished
pursuant thereto; (ii) such Assigning Lender makes no representation or warranty
and  assumes no  responsibility  with  respect  to the  financial  condition  of
Borrower or any Obligated  Party or the performance or observance by Borrower or
any  Obligated  Party of its  obligations  under the Loan  Documents;  (iii) the
Assignee  confirms that it has received copies of the Loan  Documents,  together
with  copies of the  financial  statements  referred  to in Section 7.2 and such
other  documents and  information  as it has deemed  appropriate to make its own
credit analysis and decision to enter into such Assignment and Acceptance;  (iv)
the Assignee will,  independently  and without reliance upon the  Administrative
Agent or such assignor and based on such  documents and  information as it shall
deem  appropriate  at the time,  continue  to make its own credit  decisions  in
taking or not taking action under this  Agreement and the other Loan  Documents;
(v) the Assignee  confirms  that it is an Eligible  Assignee;  (vi) the Assignee
appoints  and  authorizes  the  Administrative  Agent  to take  such  action  as
Administrative  Agent on its  behalf and  exercise  such  powers  under the Loan
Documents as are  delegated to the  Administrative  Agent by the terms  thereof,
together with such powers as are reasonably  incidental  thereto;  and (vii) the
Assignee  agrees that it will perform in accordance  with their terms all of the
obligations  which  by the  terms  of the  Loan  Documents  are  required  to be
performed by it as a Lender.

         (d) The  Administrative  Agent shall maintain at its Principal Office a
copy of each  Assignment  and  Acceptance  delivered to and accepted by it and a
register for the  recordation  of the names and addresses of the Lenders and the
Commitment  of, and principal  amount of the Advances owing to, each Lender from
time to time (the  "Register").  The entries in the Register shall be conclusive
and  binding  for  all  purposes,  absent  manifest  error,  and  Borrower,  the
Administrative  Agent,  and the  Lenders  may treat  each  Person  whose name is
recorded in the Register as a Lender  hereunder for all purposes  under the Loan
Documents.  The Register  shall be available  for  inspection by Borrower or any
Lender  at any  reasonable  time and from  time to time  upon  reasonable  prior
notice.

<PAGE>

         (e) Upon its receipt of an  Assignment  and  Acceptance  executed by an
assigning Lender and Assignee  representing  that it is an Eligible Assignee (or
other  assignee  permitted  hereunder),  together  with any Note subject to such
assignment,  the  Administrative  Agent shall, if such Assignment and Acceptance
has been  completed  and is in  substantially  the form of Exhibit B, (i) accept
such Assignment and Acceptance, (ii) record the information contained therein in
the Register,  and (iii) give prompt written notice thereof to Borrower.  Within
five (5)  Business  Days after its  receipt  of such  notice,  Borrower,  at its
expense,  shall execute and deliver to the Administrative  Agent in exchange for
the surrendered Note a new Note to the order of such Eligible Assignee (or other
assignee  permitted  hereunder)  in an  amount  equal  to  the  portion  of  the
Commitments assumed by it pursuant to such Assignment and Acceptance and, if the
Assigning  Lender has retained a portion of the  Commitments,  a new Note to the
order  of  the  Assigning  Lender  in an  amount  equal  to the  portion  of the
Commitments retained by it hereunder (each such promissory note shall constitute
a "Note" for  purposes  of the Loan  Documents).  Such new Notes  shall be in an
aggregate principal amount of the surrendered Note, shall be dated the effective
date of such Assignment and Acceptance,  and shall otherwise be in substantially
the form of Exhibit C.

         (f) Any Lender may, in connection with any assignment or  participation
or proposed  assignment or participation  pursuant to this Section,  disclose to
the Assignee or participant or proposed Assignee or participant, any information
relating to Borrower or any Subsidiary of Borrower  furnished to such, Lender by
or on behalf of Borrower or any of its Subsidiaries.

         (g)  Notwithstanding  any other term of this Agreement to the contrary,
any Lender may  (without  requesting  the  consent of either the  Administrative
Agent or  Borrower)  pledge  its Notes to a Federal  Reserve  Bank in support of
borrowings made by such Lender from such Federal Reserve Bank.

         (h)  Notwithstanding  any other term of this Agreement to the contrary,
any Lender may assign all,  or a portion of all,  of its rights and  obligations
under  this  Agreement  and  the  other  Loan  Documents   (including,   without
limitation,  its  Commitment and Advances) to an Affiliate of such Lender or any
other Lender provided that:

                  (i) such assignor  Lender has obtained the written  consent of
         the  Administrative  Agent  (which  consent  shall not be  unreasonably
         delayed or withheld)  if the effect of such  assignment  or  delegation
         shall entitle such Affiliate or other Lender to claim compensation from
         Borrower pursuant to Article IV; and

                  (ii) in every other case,  such assignor  Lender has furnished
         notice to, but not obtained the consent of, the Administrative Agent.

         Section 13.7 Survival.  All representations and warranties made in this
Agreement  or  any  other  Loan  Document  or in  any  document,  statement,  or
certificate  furnished  in  connection  with this  Agreement  shall  survive the
execution and delivery of this Agreement and the other Loan Documents  until the
Obligations  have been paid and performed in full, and no  investigation  by the
Administrative   Agent  or  any  Lender  or  any   closing   shall   affect  the
representations  and warranties or the right of the Administrative  Agent or any
Lender  to rely  upon  them.  Without  prejudice  to the  survival  of any other
obligation of Borrower  hereunder,  the obligations of Borrower under Article IV
and Sections 13.1 and 13.2 shall survive  repayment of the Notes and termination
of the Commitments.  The obligations of the Administrative Agent and the Lenders
under Section 13.18 shall survive  repayment of the Notes and termination of the
Commitments.

         Section 13.8 ENTIRE AGREEMENT. THIS AGREEMENT, THE NOTES, AND THE OTHER
LOAN DOCUMENTS  REFERRED TO HEREIN EMBODY THE FINAL,  ENTIRE AGREEMENT AMONG THE
PARTIES  HERETO  AND  SUPERSEDE  ANY  AND  ALL  PRIOR  COMMITMENTS,  AGREEMENTS,
REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER WRITTEN OR ORAL, RELATING TO THE
SUBJECT  MATTER  HEREOF AND MAY NOT BE  CONTRADICTED  OR VARIED BY  EVIDENCE  OF
PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT  ORAL  AGREEMENTS OR  DISCUSSIONS OF THE
PARTIES HERETO. THERE ARE NO ORAL AGREEMENTS AMONG THE PARTIES HERETO.

<PAGE>

         Section 13.9  Amendments,  Etc. No amendment or waiver of any provision
of this Agreement,  the Notes, or any other Loan Document to which Borrower is a
party,  nor any consent to any  departure  by Borrower  therefrom,  shall in any
event be  effective  unless  the same  shall be  agreed or  consented  to by the
Required  Lenders  and  Borrower,  and each  such  waiver  or  consent  shall be
effective only in the specific  instance and for the specific  purpose for which
given; provided, that no amendment,  waiver, or consent shall, unless in writing
and signed by all of the  Lenders and  Borrower,  do any of the  following:  (a)
increase  Commitments  of the Lenders or subject  the Lenders to any  additional
obligations;  (b) reduce the principal of, or interest on, the Notes or any fees
or other  amounts  payable to the Lenders,  (but not the  Administrative  Agent)
hereunder; (c) alter the allocation among Lenders of, or postpone any date fixed
for any payment or  prepayment  (whether or not  mandatory)  of principal of, or
interest  on,  the  Notes  or  any  fees  or  other   amounts   payable  to  the
Administrative Agent or the Lenders hereunder;  (d) change the percentage of the
Commitments  or of the  aggregate  unpaid  principal  amount of the Notes or the
number of Lenders which shall be required for the Lenders or any of them to take
any action  under this  Agreement;  (e) change any  provision  contained in this
Section 13.9; or (f) release any material  Guarantor or any material  portion of
the   Collateral,   except  in  accordance  with  the  relevant  Loan  Document.
Notwithstanding   anything  to  the  contrary  contained  in  this  Section,  no
amendment,  waiver, or consent shall be made with respect to Article XII without
the prior written consent of the Administrative Agent.

         Section  13.10  Maximum  Interest  Rate.  Regardless  of any  provision
contained  in any Loan  Document,  neither  Administrative  Agent nor any Lender
shall ever be entitled to contract  for,  charge,  take,  reserve,  receive,  or
apply, as interest on all or any part of the  Obligations,  any amount in excess
of the  Maximum  Rate,  and, if Lenders  ever do so,  then such excess  shall be
deemed a partial  prepayment of principal and treated  hereunder as such and any
remaining  excess shall be refunded to Borrower.  In determining if the interest
paid or payable  exceeds the Maximum Rate,  Borrower and Lenders  shall,  to the
maximum extent  permitted under  applicable Law, (a) treat all Advances as but a
single extension of credit (and Lenders and Borrower agree that such is the case
and that provision  herein for multiple  Advances is for convenience  only), (b)
characterize any nonprincipal payment as an expense, fee, or premium rather than
as interest,  (c) exclude voluntary prepayments and the effects thereof, and (d)
amortize,  prorate, allocate, and spread the total amount of interest throughout
the entire contemplated term of the Obligations. However, if the Obligations are
paid  and  performed  in full  prior to the end of the  full  contemplated  term
thereof, and if the interest received for the actual period of existence thereof
exceeds the Maximum  Amount,  Lenders  shall  refund such  excess,  and, in such
event,  Lenders  shall not,  to the extent  permitted  by Law, be subject to any
penalties provided by any laws for contracting for, charging, taking, reserving,
or receiving interest in excess of the Maximum Amount. The "Maximum Rate" or the
"Maximum  Amount,"  mean the "weekly  ceiling" from time to time in effect under
Texas Finance Code ss. 303.305, as amended.

         Section 13.11 Notices.  All notices and other  communications  provided
for in this  Agreement and the other Loan Documents to which Borrower is a party
shall be given or made by  telecopy  or in  writing  and  telecopied,  mailed by
certified mail return receipt requested,  or delivered to the intended recipient
at the "Address for Notices"  specified  below its name on the  signature  pages
hereof, or, as to any party at such other address as shall be designated by such
party in a notice to each other party  given in  accordance  with this  Section.
Except as otherwise provided in this Agreement, all such communications shall be
deemed to have  been  duly  given  when  transmitted  by  telecopy,  subject  to
telephone  confirmation of receipt, or when personally delivered or, in the case
of a mailed  notice,  when duly  deposited  in the mails,  in each case given or
addressed as aforesaid;  provided,  however, notices to the Administrative Agent
pursuant  to  Article  II  shall  not  be  effective   until   received  by  the
Administrative Agent.

<PAGE>

         Section 13.12  Governing Law. THIS  AGREEMENT  SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE
LAWS OF THE UNITED STATES OF AMERICA.

         Section 13.13  Counterparts.  This  Agreement may be executed in one or
more counterparts,  each of which shall be deemed an original,  but all of which
together shall constitute one and the same instrument.

         Section 13.14  Severability.  Any provision of this Agreement held by a
court of competent  jurisdiction to be invalid or unenforceable shall not impair
or invalidate  the remainder of this  Agreement and the effect  thereof shall be
confined to the provision held to be invalid or illegal.

     Section 13.15 Headings.  The headings,  captions,  and arrangements used in
this Agreement are for convenience only and shall not affect the  interpretation
of this Agreement.

         Section 13.16  Construction.  Borrower,  the Administrative  Agent, and
each Lender  acknowledges that each of them has had the benefit of legal counsel
of its own choice and has been afforded an  opportunity to review this Agreement
and the other Loan Documents with its legal counsel.

         Section 13.17 Independence of Covenants.  All covenants hereunder shall
be given  independent  effect so that if a particular action or condition is not
permitted  by any of such  covenants,  the fact that it would be permitted by an
exception to, or be otherwise  within the limitations of, another covenant shall
not avoid the  occurrence of a Default if such action is taken or such condition
exists.

         Section 13.18     Confidentiality.

         (a) The Agents and each Lender (each, a "Lending Party") agrees to keep
confidential  any Confidential  Information;  provided that nothing herein shall
prevent any Lending  Party from  disclosing  such  information  (a) to any other
Lending Party or any Affiliate of any Lending Party,  or any officer,  director,
employee, agent, or advisor of any Lending Party or any Affiliate of any Lending
Party, (b) to any other Person if reasonably incidental to the administration of
the credit  facility  provided  herein,  (c) as  required by any law,  rule,  or
regulation,  (d) upon the order of any court or administrative  agency, (e) upon
the request or demand of any regulatory  agency or authority,  (f) in connection
with any  litigation  to which  such  Lending  Party may be a party,  (g) to the
extent  necessary  in  connection  with the  exercise  of any remedy  under this
Agreement  or  any  other  Loan   Document,   and  (h)  subject  to   provisions
substantially  similar  to those  contained  in this  Section,  to any actual or
proposed   participant  or  Assignee.   Furthermore,   and  notwithstanding  the
foregoing,  no Lending Party shall provide any  Confidential  Information to any
officer,  director,  employee,  agent or advisor of any  Affiliate  of a Lending
Party if such officer, director,  employee, agent or advisor's position involves
the ability to transact  trades in, or solicit or accept orders for the purchase
or sale of, the common stock of Borrower.

         (b) The  Lending  Parties are aware that the United  States  securities
laws prohibit any Person who has received material,  non-public information such
as is the  subject of this  Section  13.18  from an issuer  from  purchasing  or
selling the securities of such issuer or from  communicating such information to
any other Person under circumstances in which it is reasonably  foreseeable that
such Person is likely to purchase or sell such securities.

<PAGE>

         (c) The Companies and the Lending  Parties agree that monetary  damages
would not be a  sufficient  remedy for any breach of this  Section  13.18 by the
Lending Parties and that, in addition to all other remedies, the Companies shall
be entitled to specific  performance and injunction or other equitable relief as
a remedy for any such breach.

         (d) The  restrictions  and  obligations  of this  Section  13.18  shall
survive the repayment of the  Obligations and shall continue to bind the Lending
Parties.

         Section 13.19  Restatement of Original  Credit  Agreement.  The parties
hereto agree that, after all conditions  precedent set forth in Section 6.1 have
been satisfied or waived:  (a) the Obligations  (as defined  herein)  represent,
among  other  things,  the  amendment,   extension,   and  modification  of  the
"Obligations" (as defined in the Original Credit Agreement);  (b) this Agreement
is intended to, and does hereby,  restate,  consolidate,  renew, extend,  amend,
modify,  supersede,  and replace the Original Credit  Agreement in its entirety;
(c) the Notes, if any, executed pursuant to this Agreement amend, renew, extend,
modify,  replace,  substitute  for, and supersede in their  entirety (but do not
extinguish,  the Debt arising under) the promissory notes issued pursuant to the
Original Credit Agreement,  which existing promissory notes shall be returned to
Administrative  Agent  promptly  after the Closing Date,  marked  "cancelled and
replaced," and, thereafter,  delivered by Administrative Agent to Borrower;  and
(d) the entering into and performance of their respective obligations under this
Agreement and the transactions evidenced hereby do not constitute a novation.

         Section 13.20  Assignments and Assumptions  Among Lenders.  The Lenders
hereby agree among  themselves  (and Borrower and  Guarantors  hereby consent to
such agreement) that,  concurrently  with the execution  hereof,  there shall be
deemed  to  have  occurred  assignments  and  assumptions  with  respect  to the
Obligations,  liens,  rights, and obligations under this Agreement and the other
Loan Documents (including, without limitation, the Commitments) such that, after
giving effect to such assignments and assumptions,  the Lender's Commitments are
as stated on  Schedule  1, and the  Lenders  hereby  make such  assignments  and
assumptions.

         Section 13.21 Waiver of Jury Trial. TO THE FULLEST EXTENT  PERMITTED BY
APPLICABLE LAW, BORROWER HEREBY  IRREVOCABLY AND EXPRESSLY WAIVES ALL RIGHT TO A
TRIAL BY JURY IN ANY ACTION,  PROCEEDING,  OR  COUNTERCLAIM  (WHETHER BASED UPON
CONTRACT,  TORT,  OR  OTHERWISE)  ARISING  OUT OF OR RELATING TO ANY OF THE LOAN
DOCUMENTS OR THE TRANSACTIONS  CONTEMPLATED  THEREBY OR THE ACTIONS OF ANY AGENT
OR ANY LENDER IN THE NEGOTIATION, ADMINISTRATION, OR ENFORCEMENT THEREOF.

<PAGE>

         Section  13.22  Choice of Forum;  Consent to  Service  of  Process  and
Jurisdiction.  Any suit,  action or proceeding  against Borrower with respect to
this Agreement or the Loan  Documents,  or any judgment  entered by any court in
respect  thereof,  may be brought  in the  courts of the State of Texas,  Travis
County,  or in the United  States courts  located in the State of Texas,  as the
Administrative  Agent shall,  at the direction of the Required  Lenders elect in
their sole discretion,  and Borrower  irrevocably  submits to the  non-exclusive
jurisdiction  of such courts for the purpose of any suit,  action or proceeding.
Borrower  irrevocably  consents to the service of process in any suit, action or
proceeding in said court by the mailing thereof by the  Administrative  Agent by
registered  or certified  mail,  postage  prepaid to  Borrower's  address  shown
opposite its name on the signature pages hereof. Nothing herein or in any of the
other Loan Documents shall affect the right of the Administrative Agent to serve
process in any other  manner  permitted  by law or shall  limit the right of the
Administrative  Agent to bring any action or proceeding against Borrower or with
respect  to any of its  property  in  courts  in other  jurisdictions.  Borrower
irrevocably  waives any objections  which it may now or hereafter have to laying
of venue of any suit,  action or  proceeding  arising out of or relating to this
Agreement or the other Loan Documents brought in the courts located in the State
of Texas,  Dallas County,  and hereby further  irrevocably waives any claim that
any such suit,  action or proceeding  brought in any such court has been brought
in any  inconvenient  forum.  Any action or proceeding  by Borrower  against the
Administrative  Agent or any Lender shall be brought only in a court  located in
Travis County, Texas.

         Section  13.23  Chapter 346.  Borrower  agrees that Chapter 346, of the
Texas Finance Code, as amended (which  regulates  certain  revolving credit loan
documents and revolving tri-party accounts) does not apply to the Obligations.

                     REMAINDER OF PAGE INTENTIONALLY BLANK.

                             SIGNATURE PAGES FOLLOW.

<PAGE>

                   Fourth Amended and Restated Loan Agreement

                                 Signature Page

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

                                    BORROWER:

                                                PRIME MEDICAL SERVICES, INC.

                                                By:/s/ Teena E. Belcik
                                                       Teena E. Belcik
                                                       Vice President-Treasurer

                                                   Address for Notices:

                                                   1301 Capital of Texas Highway

                                                   Suite C-300
                                                   Austin, Texas 78746
                                                   Attention: Treasurer

                                                   Fax No.: (512) 328-8510
                                                   Telephone No.: (512) 314-4554

<PAGE>

                                                     BANK OF AMERICA:

                                                     BANK OF AMERICA, N.A.

                                            as Administrative Agent and a Lender

                                                 By: /s/ Daniel H. Penkar
                                                          Daniel H. Penkar
                                                          Senior Vice President

                                         Address for Notices:
                                         515 Congress Avenue, 11th Floor
                                         Post Office Box 908
                                         Austin, Texas  78701-0908
                                         Attention: Wade Morgan

                                         Fax No.: (512) 397-2052
                                         Telephone No.: (512) 397-2241

                                         Lending Office for Base Rate Advances:
                                         515 Congress Avenue, 11th Floor
                                         Post Office Box 908
                                         Austin, TX  78701-0908

                                         Lending Office for Eurodollar Advances:
                                         515 Congress Avenue, 11th Floor
                                         Post Office Box 908
                                         Austin, TX  78701-0908

<PAGE>

                                   BANKBOSTON:

                                           BANKBOSTON, N.A.,

                                           as Documentation Agent, and  a Lender

                                           By: /s/ Walter J. Marullo
                                                Walter J. Marullo
                                                Vice President

                                    Address for Notices:

                                    100 Federal Street, MS 01-08-05
                                    P.O. Box 2016
                                    Boston, Massachusetts 02106
                                    Attention: Walter J. Marullo, Vice President

                                            Fax No.: (617)  434-2472
                                            Telephone No.: (617)  434-2308

                                          Lending Office for Base Rate Advances:
                                           100 Federal Street
                                           P. 0. Box 2016
                                           Boston, MA  02106

                                         Lending Office for Eurodollar Advances:
                                           100 Federal Street
                                           P.O. Box 2016
                                           Boston, MA  02106

<PAGE>

                                                     BANK ONE, TEXAS, N.A.,

                                                         as Lender

                                               By: Edward W. Lick, Jr.
                                               Edward W. Lick, Jr.
                                               Vice President

                                                  Address for Notices:
                                                  221 West 6th Street, Suite 200
                                                  Austin, Texas 78701
                                                  Attention: Ed Lick

                                                  Fax No.: (512) 479-5720
                                                  Telephone No.: (512) 479-5730

                                         Lending Office for Base Rate Advances:
                                          Bank One, Austin
                                          221 West 6th Street, Suite 200
                                          Austin, TX  78701

                                         Lending Office for Eurodollar Advances:
                                          Bank One, Austin
                                          221 West 6th Street, Suite 200
                                          Austin, TX  78701

<PAGE>

                                         CREDIT LYONNAIS NEW YORK BRANCH

                                              as Lender

                                                     By: /s/ John Oberle
                                                              John Oberle
                                                              Vice President

                                                 Address for Notices:
                                                 1301 Avenue of the Americas
                                                 New York, New York 10019-6022
                                                 Attention: John Oberle

                                                 Fax No.: (212) 261-3440
                                                 Telephone No.: (212) 261-7344

                                         Lending Office for Base Rate Advances:
                                         Credit Lyonnais New York Branch
                                         1301 Avenue of the Americas
                                         New York, NY  10019-6022

                                         Lending Office for Eurodollar Advances:
                                         Credit Lyonnais New York Branch
                                         1301 Avenue of the Americas
                                         New York, NY  10019-6022

<PAGE>

                                        FLEET NATIONAL BANK,

                                               as Lender

                                       By: /s/ Walter J. Marullo
                                                   Walter J. Marullo
                                                   Vice President

                                    Address for Notices:

                                    100 Federal Street, MS 01-08-05
                                    P.O. Box 2016
                                    Boston, Massachusetts 02106
                                    Attention: Walter J. Marullo, Vice President

                                          Fax No.: (617) 434-2472
                                          Telephone No.: (617) 434-2308

                                          Lending Office for Base Rate Advances:
                                                     Fleet National Bank
                                                     One Federal Street
                                                     Mail Stop: MA OF D07B
                                                     Boston, MA  02110

                                         Lending Office for Eurodollar Advances:
                                                     Fleet National Bank
                                                     One Federal Street
                                                     Mail Stop:  MA OF D07B
                                                     Boston, MA  02110

<PAGE>

                                 IMPERIAL BANK,

                                    as Lender

                                                     By: /s/ M. Metheany
                                                     Name: M. Metheany
                                                     Title: Vice President

                                                  Address for Notices:
                                                  226 Airport Parkway
                                                  San Jose, California  95110
                                                  Attention: Kelly Davis

                                                  Fax No.: (408) 451-8586
                                                  Telephone No.: (408) 451-8589

                            Lending Office for Base Rate Advances:
                                                     Imperial Bank
                                                     226 Airport Parkway
                                                     San Jose, CA  95110

                            Lending Office for Eurodollar Advances:
                                                     Imperial Bank
                                                     226 Airport Parkway
                                                     San Jose, CA  95110

<PAGE>

                              LASALLE BANK, NATIONAL ASSOCIATION

                                    as Lender

                                                     By: /s/ Dana Friedman
                                                     Name: Dana Friedman
                                                     Title: Lending Officer

                                            Address for Notices:
                                            135 South LaSalle Street
                                            Chicago, Illinois  60603
                                            Attention: Dana Friedman

                                            Fax No.: (312) 904-6457
                                            Telephone No.: (312) 904-6583

                                         Lending Office for Base Rate Advances:
                                         LaSalle Bank, National Association
                                         135 South LaSalle Street
                                         Chicago, IL  60603

                                         Lending Office for Eurodollar Advances:
                                         LaSalle Bank, National Association
                                         135 South LaSalle Street
                                         Chicago, IL  60603

<PAGE>

                                        COOPERATIEVE CENTRALE RAIFFEISEN -
                                        BOERENLEENBANK B.A., "RABOBANK
                                        NEDERLAND", NEW YORK BRANCH,  as Lender

                                                     By: /s/ J. David Thomas
                                                              J. David Thomas
                                                              Vice President

                                                     By: /s/ W. Pieter C. Kodde
                                                              W. Pieter C. Kodde
                                                              Vice President

                                        Address for Notices:
                                        245 Park Avenue
                                        New York, New York  10167
                                        Attention: Corporate Services Department

                                                  Fax. No.: (212) 818-0233
                                                  Telephone No.: (212) 916-7800

                                           cc:     1201 West Peachtree Street,
                                                   Suite 3450
                                                   Atlanta, Georgia 30309-3400
                                                   Attention: Terrell Boyle

                                                   Fax. No.: (404) 877-9150
                                                   Telephone No.: (404) 877-9106

                                      Lending Office for Base Rate Advances:
                                            Cooperatieve Centrale Raiffeisen -
                                            Boerenleenbank B.A., "Rabobank
                                            Nederland", New York Branch
                                            245 Park Avenue
                                            New York, NY  10167

                                        Lending Office for Eurodollar Advances:
                                           Cooperatieve Centrale Raiffeisen -
                                           Boerenleenbank B.A., "Rabobank
                                           Nederland", New York Branch
                                           245 Park Avenue
                                           New York, NY  10167

<PAGE>

GUARANTY FEDERAL BANK, F.S.B.

By: /s/ Chris Harkrider
       Chris Harkrider
       Vice President

Addresses for Notices:

301 Congress Avenue
Suite 300
Austin, TX  78701
Attention:  Chris Harkrider

Fax No.:     (512) 320-1041
Telephone No.:  (512) 320-1205

Lending Office for Base Rate Advances:

Guaranty Federal Bank, F.S.B.
8333 Douglas Avenue
Dallas, TX 75225

Lending Office for Eurodollar Advances:

Guaranty Federal Bank, F.S.B.
8333 Douglas Avenue
Dallas, TX 75225Pledge and Security Agreement

                          PLEDGE AND SECURITY AGREEMENT

         THIS  PLEDGE  AND  SECURITY  AGREEMENT  (the  "Agreement")  dated as of
January 31,  2000,  is by and between OHIO LITHO,  INC., a Delaware  corporation
("Pledgor"), whose street address is 1301 Capital of Texas Highway, Suite C-300,
Austin, Texas 78746-6550,  for the benefit of BANK OF AMERICA,  N.A., a national
banking association ("B of A"), whose street address is 901 Main Street, Dallas,
Texas 75202, not in its individual  capacity but solely as administrative  agent
for itself and each of the other banks or lending institutions (each, a "Lender"
and collectively, the "Lender") which is or may from time to time become a party
to the Loan Agreement (as hereinbelow defined) (in such capacity,  together with
its successors in such capacity, the "Administrative Agent").

                                R E C I T A L S:

     A. Prime Medical Services, Inc., a Delaware corporation  ("Borrower"),  has
entered into that certain Fourth Amended and Restated Loan Agreement dated as of
the date hereof with B of A as Administrative Agent and as a Lender, BankBoston,
N.A., as Documentation Agent and as a Lender, and the other Lenders from time to
time party thereto, as amended,  waived, restated, and supplemented from time to
time ("Loan Agreement").

         B. Pledgor and certain  other  guarantors  have  executed  that certain
Guaranty  Agreement  dated as of the date  hereof  (as the same may be  amended,
supplemented or modified from time to time, the  "Guaranty"),  pursuant to which
Pledgor has guaranteed to the Agents (as defined in the Loan  Agreement) and the
Lenders  the full and  complete  payment  and  performance  of the  liabilities,
obligations,  and  indebtedness  of the  Borrower  to the Agents and the Lenders
under the Loan Documents (as defined in the Loan Agreement).

     C. As a condition to entering into the Loan Agreement, Pledgor must execute
and deliver this Agreement.

         NOW  THEREFORE,  in  consideration  of the  premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, Pledgor agrees with the Administrative Agent as follows:

                                    ARTICLE I

                                   DEFINITIONS

         (a) Each term used herein and defined in the Loan Agreement  shall have
the  meaning  assigned to it in the Loan  Agreement,  unless  otherwise  defined
herein or the context otherwise requires.

         (b) In addition,  as used herein,  the  following  terms shall,  unless
otherwise indicated, have the following meanings:

         "Borrower" has the meaning set forth in the recitals.

         "Code" shall mean the Uniform Commercial Code as in effect in the State
of Texas.

<PAGE>

                                                   Pledge and Security Agreement

                                        3

         "Collateral"  shall mean the assets and interests of Pledgor identified
in Section 2.1 hereof.

         "Event of  Default"  shall have the  meaning  assigned  to such term in
Section 5.1.

         "Guaranty" shall mean that certain  Guaranty  Agreement dated as of the
date hereof, executed by Pledgor and certain other guarantors for the benefit of
the Agents and the Lenders, guaranteeing the full payment and performance of the
Obligations, as amended, modified, confirmed, and extended from time to time.

         "Partnerships"  shall mean (a) those partnerships and limited liability
companies  listed on  Exhibit  A  attached  hereto  and  incorporated  herein by
reference,  as such  partnerships  or limited  liability  companies exist or may
hereinafter be restated,  amended or restructured,  (b) any  partnership,  joint
venture,  or limited  liability  company in which  Pledgor  shall,  at any time,
become  a  limited  or  general  partner,   venturer,  or  member,  or  (c)  any
partnership, joint venture or corporation formed as a result of the restructure,
reorganization or amendment of the Partnerships.

         "Partnership  Agreements"  shall  mean (a) those  agreements  listed on
Exhibit B attached hereto and  incorporated  herein by reference  (together with
any  modifications,  amendments or  restatements  thereof),  and (b) partnership
agreements,  joint venture agreements,  or organizational  agreements for any of
the partnerships,  joint ventures,  or limited liability  companies described in
clause  (b) of  the  definition  of  "Partnerships"  above  (together  with  any
modifications,  amendments or restatements thereof), and "Partnership Agreement"
means any one of the Partnership Agreements.

         "Pledged Partnership Interests" shall mean all of Pledgor's partnership
interests,  whether general or limited, venture, or membership interests, in the
Partnerships,  including,  without limitation, all of Pledgor's right, title and
interest now or hereafter accruing under the Partnership Agreements with respect
to any  interest  now owned or  hereafter  acquired  or owned by  Pledgor in the
Partnerships,  and including all  distributions,  allocations,  proceeds,  fees,
preferences,  payments or other benefits,  which Pledgor now is or may hereafter
become  entitled to receive with respect to such  interests in the  Partnerships
and with respect to the repayment of all loans now or hereafter  made by Pledgor
to the Partnerships,  and Pledgor's undivided  percentage interest in the assets
of the Partnerships.

         "Secured  Indebtedness" shall have the meaning assigned to such term in
Section 2.1(c) hereof.

         "Security Interests" shall mean the pledge, collateral assignment,  and
security interests securing the Secured  Indebtedness,  including (i) the pledge
and  security  interest in the  Pledged  Partnership  Interests  granted in this
Agreement  and  (ii)  all  other  security  interests  created  or  assigned  as
additional security for the Secured  Indebtedness  pursuant to the provisions of
this Agreement.

         (c) Whenever the context so requires,  the neuter  gender  includes the
masculine and  feminine,  and the singular  number  includes the plural and vice
versa.

<PAGE>

                                   ARTICLE II

                            COLLATERAL AND OBLIGATION

         SECTION 2.1       Grant of Security Interest.
                           --------------------------

         (a) As collateral  security for Secured  Indebtedness,  Pledgor  hereby
pledges and grants to the Administrative  Agent, for the benefit of the Lenders,
a first  priority  lien on and  security  interest  in and to,  and  agrees  and
acknowledges  that the  Administrative  Agent has, and shall continue to have, a
security interest in and to, and assigns, transfers,  pledges and conveys to the
Administrative  Agent, all of Pledgor's right,  title and interest in and to the
following  described  collateral  (the  "Collateral")  now  owned  or  hereafter
acquired,  wherever  located,  howsoever  arising or  created,  and  whether now
existing or hereafter arising, existing or created:

                    (i)  the  Pledged  Partnership  Interests  and all rights of
                         Pledgor with respect  thereto and all proceeds,  income
                         and profits therefrom;

                  (ii)     all of Pledgor's  distribution rights, income rights,
                           liquidation  interest,   accounts,  contract  rights,
                           general intangibles,  notes, instruments,  drafts and
                           documents   relating  to  the   Pledged   Partnership
                           Interests;

                  (iii)    to the extent attributable to the Pledged Partnership
                           Interests,  all promissory  notes,  notes receivable,
                           accounts,  accounts  receivable and instruments owned
                           or held by Pledgor or, in which Pledgor owns or holds
                           an   interest,    evidencing   obligations   of   the
                           Partnerships;

                  (iv)     all liens, security interests,  collateral,  property
                           and  assets  securing  any of the  promissory  notes,
                           notes receivables,  instruments,  accounts receivable
                           and other  claims and  interest  described  in clause
                           (iii) above;

                    (v)  all books, files, computer records,  computer software,
                         electronic  information  and other  files,  records  or
                         information  relating  to any or all of the  foregoing;
                         and

                  (vi)     all substitutions,  replacements, products, proceeds,
                           income and profits arising from any of the foregoing;
                           including without limitation insurance proceeds.

         (b)  The  Security   Interests  are  granted  and  the   Collateral  is
collaterally  assigned as security only and shall not subject the Administrative
Agent or any holder of the  Secured  Indebtedness  to, or transfer or in any way
affect or modify,  any obligation or liability of Pledgor with respect to any of
the Collateral.

         (c)  The   Collateral   shall   secure   the   following   obligations,
indebtedness,  and liabilities  (whether at stated maturity,  by acceleration or
otherwise)  (all  such   obligations,   indebtedness,   and  liabilities   being
hereinafter sometimes called the "Secured Indebtedness"):

                    (i)  the  Obligations and the  obligations,  liabilities and
                         indebtedness  of Pledgor to the Agents and the  Lenders
                         under the Guaranty;

<PAGE>

                  (ii)     all reasonable costs and expenses, including, without
                           limitation,  all reasonable attorneys' fees and legal
                           expenses, incurred by any of the Agents or any Lender
                           to preserve and maintain the Collateral,  collect the
                           obligations   herein  described,   and  enforce  this
                           Agreement; and

          (iii)all  extensions,  renewals,  and  modifications  of  any  of  the
               foregoing.

     SECTION 2.2 Consent.  To the extent any Partnership  Agreement requires the
consent or agreement of Pledgor to the transfer,  conveyance,  or encumbrance as
security  for the  Secured  Indebtedness  of all or any  portion of the  Pledged
Partnership  Interests,  Pledgor hereby irrevocably consents to (a) the grant of
the security  interest  described in Section 2.1 of this Agreement,  and (b) any
transfer or  conveyance  of the Pledged  Partnership  Interests  pursuant to the
Administrative  Agent's exercise of its rights and remedies under Section 5.4 of
this Agreement or under any other Loan Document.

         SECTION 2.3 Pledgor  Remains  Liable.  Notwithstanding  anything to the
contrary contained herein, (a) Pledgor shall remain liable under the Partnership
Agreements  to the  extent set forth  therein  to perform  all of its duties and
obligations  thereunder  to the same  extent as if this  Agreement  had not been
executed  (b) the  exercise  by the  Administrative  Agent of any of its  rights
hereunder shall not release Pledgor from any of its duties or obligations  under
the contracts and  agreements  included in the  Collateral,  and (c) neither the
Administrative Agent nor any Lender shall have any obligation or liability under
the  Partnership  Agreements  by  reason  of  this  Agreement,   nor  shall  the
Administrative  Agent  or  any  Lender  be  obligated  to  perform  any  of  the
obligations or duties of Pledgor  thereunder or to take any action to collect or
enforce any claim for payment assigned hereunder.

                                   ARTICLE III

                         REPRESENTATIONS AND WARRANTIES

         Pledgor hereby represents and warrants to the  Administrative  Agent as
follows:

         (a) Pledgor has good and indefeasible title to the Pledged  Partnership
Interests  and  other  Collateral  free and  clear of any  Lien  except  for the
Security  Interests created by this Agreement and the security interests granted
in  favor  of  Bank of  America,  N.A.,  as  Administrative  Agent  ("Refractive
Administrative  Agent")  under the Loan  Agreement  dated the date  hereof  (the
"Refractive  Loan  Agreement")  among  Prime  Refractive   Management,   L.L.C.,
Refractive  Administrative Agent, BankBoston,  N.A., as documentation agent, and
the lenders from time to time party thereto ("Refractive Lenders"),  and has all
necessary  authority to pledge and collaterally  assign the Pledged  Partnership
Interests and other Collateral as security for the Secured  Obligations and such
assignment  and transfer is not contrary to or in conflict with the  Partnership
Agreements or any other agreement;

         (b) No  financing  statement  or other  instrument  similar  in  effect
covering all or any part of the  Collateral is on file in any recording  office,
except such as may have been filed in favor of the Administrative Agent relating
to this Agreement or those in favor of Refractive Administrative Agent;

     (c) This  Agreement  has been duly executed and delivered by Pledgor and is
the legal and binding  obligation of Pledgor  enforceable in accordance with its
terms;

<PAGE>

         (d) Upon  execution  of this  Agreement  and an  appropriate  financing
statement  by  Pledgor  and the  recording  of the  financing  statement  in the
appropriate office, the Administrative  Agent will have a valid, first and prior
perfected security interest in the Collateral;

         (e) Neither the  execution  and  delivery  of this  Agreement,  nor the
consummation of any of the transactions hereby contemplated, nor compliance with
the terms and provisions hereof, will contravene or materially conflict with (i)
any material  provision of law,  statute or  regulation  to which Pledgor or the
Partnerships  is  subject  or  (ii)  any  judgment,  license,  order  or  permit
applicable to Pledgor or the Partnerships.  No consent, approval,  authorization
or  order of any  court,  governmental  authority,  partner  or  third  party is
required that has not been received or taken (i) for the grant by Pledgor of the
Security  Interests,  (ii) for the  execution,  delivery or  performance of this
Agreement by Pledgor,  (iii) for the  perfection of the Security  Interests,  or
(iv) except for such notices as are required by the Code or the Loan  Agreement,
for  the  exercise  by the  Administrative  Agent  of its  rights  and  remedies
hereunder (provided,  however,  that the purchaser of the Collateral at any sale
thereof  pursuant to Section 5.4 hereof may be required to obtain the consent of
the partners in the  Partnerships  and/or satisfy other  conditions set forth in
the Partnership  Agreements prior to such purchaser's  admission as a partner in
the Partnership);

     (f) The chief  executive  office and principal place of business of Pledgor
is in Austin, Travis County, Texas; and

         (g) To the best  knowledge  and belief of  Pledgor,  Pledgor  has fully
performed each and every one of his obligations and duties under the Partnership
Agreements  on or prior to the date due;  Pledgor has not received any notice of
any  default  in  the  performance  of his  obligations  under  the  Partnership
Agreements or of any situation which could give rise to such an event of default
thereunder.

                                   ARTICLE IV

                               PLEDGOR'S COVENANTS

         Pledgor hereby covenants and agrees with the Administrative  Agent that
until the Secured Indebtedness is paid and performed in full:

     (a)  Pledgor  will  not  cause,  permit  or  consent  to any  amendment  or
modification  to the  Partnership  Agreements  in effect  as of the date  hereof
except as permitted in the Loan Agreement;

         (b)  Pledgor  will  pay and  discharge  promptly  when  due all  taxes,
assessments,  forced contributions,  governmental charges, fines, penalties, and
any other lawful claims, of every  description,  payable by Pledgor with respect
to (or  which,  if not paid  could  result  in an  encumbrance  upon) any of the
Collateral, except as otherwise permitted by the terms of the Loan Agreement. In
the  event  that  Pledgor  should,  for any  reason,  fail to pay and  discharge
promptly any taxes,  assessments,  forced  contributions,  governmental charges,
fines, or penalties when due (subject to the provisions of the Loan  Agreement),
then the Administrative  Agent shall be authorized,  but shall not be obligated,
to pay the same, with full  subrogation to all rights of any Person by reason of
such  payment,  and the  amounts  so paid,  together  with  interest  thereon as
provided herein, shall be secured by the Security Interests;

<PAGE>

         (c) Pledgor will not sell, transfer, mortgage or otherwise encumber any
Collateral  in any  manner,  except  for  the  security  interest  in  favor  of
Refractive  Administrative Agent, without first obtaining the written consent of
the  Administrative  Agent.  Any  written  consent to any such  sale,  mortgage,
transfer or encumbrance  shall not be construed to be a waiver of this provision
in respect of any subsequent proposed sale, mortgage, transfer or encumbrance;

         (d)  Pledgor  will,  at its  expense and in such manner and form as the
Administrative Agent may from time to time reasonably require, execute, deliver,
file  and  record  any  financing   statement,   specific  assignment  or  other
instruments,  certificates  or  papers  and take any  other  action  that may be
necessary or desirable,  or that the Administrative  Agent may from time to time
reasonably  request,  in order to  create,  preserve,  perfect or  validate  any
Security Interest or to enable the Administrative  Agent to exercise and enforce
its rights  hereunder with respect to any of the Collateral.  In the event,  for
any  reason,  that the law of any  jurisdiction  other  than the  State of Texas
becomes or is applicable to the Collateral,  or any part thereof, Pledgor agrees
to execute and deliver all such instruments and to do all such other things that
may be necessary or  appropriate  to preserve,  protect and enforce the Security
Interests of the Administrative  Agent under the law of such other jurisdiction,
to at least the same extent that the Security Interests would be protected under
the Code. To the extent permitted by applicable law,  Pledgor hereby  authorizes
the  Administrative  Agent  to  execute  and  file,  in the name of  Pledgor  or
otherwise,  Uniform Commercial Code financing statements that the Administrative
Agent in its sole  discretion  may deem  necessary  or  appropriate  to  further
perfect the Security Interests;

         (e) If Pledgor receives,  by virtue of being or having been an owner of
any of the Collateral, any notes, other instruments, options, cash distributions
or any other distribution,  resulting from a Capital Event (hereinafter defined)
Pledgor  shall  receive the same in trust for the benefit of the  Administrative
Agent,  shall immediately  notify the  Administrative  Agent of such receipt and
shall  immediately  take all such actions and execute all such  documents as the
Administrative  Agent deems  necessary or  appropriate  to continue or create as
first and prior perfected Liens, in favor of the  Administrative  Agent covering
such notes, other instruments,  options, cash distributions. As used herein, the
term  "Capital  Event" shall mean any event  generating or resulting in revenues
not attributable to the normal business operations of the Partnerships including
without   limitation,   any  mortgaging  of  assets,   refinancing  of  existing
indebtedness of any Partnership,  condemnation of any assets of any Partnership,
sale or transfer of any assets of any Partnership outside the ordinary course of
business,  or payment of insurance proceeds.  At all times other than during the
continuance  of an Event of Default,  Pledgor  shall be entitled to receive free
from the security  interest  hereof any note,  other  instrument,  option,  cash
distribution  or any other  distribution  resulting  from any event other than a
Capital Event;

         (f) Pledgor will notify the  Administrative  Agent in writing  prior to
the removal of Pledgor's chief  executive  office or principal place of business
from the State of Texas;

         (g) Pledgor shall cause to be obtained any and all waivers and consents
necessary to make  effective the grant  contained in and to perfect the security
interest  granted to the  Administrative  Agent  pursuant to Section 2.1 hereof,
including without limitation,  all necessary waivers and consents from the other
partners, if any, of each Partnership;

         (h) Pledgor shall perform fully all obligations  imposed upon it by any
agreements  or  instruments  concerning  all or  any  part  of  the  Collateral,
including  without  limitation the Partnership  Agreements and shall maintain in
full force and effect all such agreements and  instruments,  and shall not amend
or modify,  or consent to the amendment or  modification  of such  agreements or
instruments, without the prior written consent of the Administrative Agent; and

<PAGE>

         (i)  Pledgor  shall  promptly  notify the  Administrative  Agent of any
material adverse change in any material fact or material circumstance  warranted
or represented by Pledgor in this Agreement or in any other writing furnished by
Pledgor to the  Administrative  Agent in connection  with the  Collateral or the
Secured Indebtedness,  and shall promptly notify the Administrative Agent of any
claim,  action or  proceeding  affecting  title to the  Collateral,  or any part
thereof,  or  the  Security  Interests  herein,  and,  at  the  request  of  the
Administrative  Agent, shall appear and defend, at Pledgor's  expense,  any such
action or proceeding.

                                    ARTICLE V

                    GENERAL AUTHORITY AND POWERS AND REMEDIES

         SECTION 5.1       Events of Default.
                           -----------------

         Pledgor shall be in default under this  Agreement upon the happening of
any of the  following  events  or  conditions  (hereinafter  called an "Event of
Default"):

         (a)      An Event of Default under the Loan Agreement shall occur; or

     (b) The ownership of any of the  Collateral  becomes  vested in a person or
entity other than Pledgor, except as permitted hereunder; or

     (c) The Administrative Agent's Liens in any of the Collateral should become
unenforceable, or cease to be first priority Liens.

         SECTION 5.2 Right to Receive  Distributions.  The Administrative  Agent
shall  have the  right,  at any time  following  the  occurrence  and during the
continuation of an Event of Default,  to receive all payments and  distributions
made to Pledgor upon or with  respect to the  Collateral  and Pledgor  agrees to
take all such action as the  Administrative  Agent may reasonably deem necessary
or appropriate to give effect to such right.

         SECTION 5.3 General Authority.  Pledgor hereby irrevocably appoints the
Administrative  Agent,  and its  successors  and  assigns,  the true and  lawful
attorney-in-fact  of Pledgor,  with full power of  substitution,  in the name of
Pledgor,  for the sole  use and  benefit  of the  Administrative  Agent,  but at
Pledgor's expense,  to the extent permitted by law to exercise,  at any time and
from time to time  following the  occurrence  and during the  continuance  of an
Event of Default,  all or any of the following powers with respect to all or any
of the Collateral:

     (a) to ask,  demand,  sue for,  collect,  receive and give  acquittance and
receipts for any and all monies due or to become due upon or by virtue thereof;

     (b) to  receive,  endorse,  and  collect  any drafts or other  instruments,
documents and chattel paper,
in connection with clause (a) preceding;

     (c) to  settle,  compromise,  compound,  prosecute  or defend any action or
proceeding with respect thereto;

<PAGE>

         (d)  subject  to  Section  5.4  hereof,  to sell,  transfer,  assign or
otherwise  deal in or with  the  same  or the  proceeds  thereof  as  fully  and
effectually as if the Administrative Agent were the absolute owner thereof; and

     (e) to extend  the time of payment  of any or all  thereof  and to make any
allowance and other adjustments with reference thereto.

In addition,  the  Administrative  Agent, at any time, either before or after an
Event of Default, shall have the right, together with such accountants and other
agents or representatives as they may from time to time designate,  to visit and
inspect the Partnerships'  properties,  assets, books, records and documents and
to discuss the Partnerships'  affairs,  finances and accounts with Pledgor's and
the Partnerships'  representatives,  officers or directors,  during all business
hours as the  Administrative  Agent  may  designate,  and to make and take  away
copies of the  Partnerships'  records  at the  Administrative  Agent's  expense.
Pledgor  shall  furnish  to  Administrative  Agent  any  information  reasonably
requested by the Administrative Agent in connection with the Collateral. Pledgor
will maintain complete and accurate books and records regarding the Collateral.

         SECTION 5.4       Remedies Upon Default.
                           ---------------------

         (a) If any Event of Default shall have occurred and is continuing,  the
Administrative  Agent,  at its option,  without demand,  presentment,  notice of
acceleration,  intention to  accelerate or other notice (which are fully waived)
may:

                  (1) exercise all the rights of a secured  party under the Code
         (whether  or not the Code is in effect in the  jurisdiction  where such
         rights are exercise, unless prohibited by applicable law).

               (2) apply the cash, if any, then held by the Administrative Agent
          as Collateral as specified in Section 5.6.

                  (3) sell all of the  Collateral  or any part thereof at public
         or private sale or at any broker's board or on any securities exchange,
         for cash,  upon  credit or for  future  delivery,  and at such price or
         prices as the  Administrative  Agent may reasonably deem  satisfactory.
         Upon the  Administrative  Agent's  demand,  Pledgor will take all steps
         necessary to prepare the  Collateral  for and  otherwise  assist in any
         proposed  disposition  of the  Collateral.  Any  holder of the  Secured
         Indebtedness  may be the  purchaser of any or all of the  Collateral so
         sold at any public sale (or, if the Collateral is of a type customarily
         sold in a  recognized  market or is of a type  which is the  subject of
         widely distributed standard price quotations,  at any private sale) and
         thereafter  hold the same  absolutely,  free from any right or claim of
         whatsoever kind. Any holder of the Secured  Indebtedness shall have the
         right to offset  the amount of its bid  against an equal  amount of the
         Secured Indebtedness held by such holder.

<PAGE>

         Pledgor agrees that, because of the Securities Act of 1933, as amended,
         or any other laws or regulations,  and for other reasons,  there may be
         legal  and/or  practical  restrictions  or  limitations  affecting  the
         Administrative  Agent in any attempts to dispose of certain portions of
         the  Collateral  and for the  enforcement  of their  rights.  For these
         reasons,  the Administrative Agent is hereby authorized by Pledgor, but
         not obligated,  upon the occurrence and during the  continuation  of an
         Event of Default,  to sell all or any part of the Collateral at private
         sale,  subject to  investment  letter or in any other manner which will
         not require the  Collateral,  or any part thereof,  to be registered in
         accordance  with the Securities  Act of 1933, as amended,  or the rules
         and  regulations   promulgated   thereunder,   or  any  other  laws  or
         regulations,  at a  reasonable  price  at such  private  sale or  other
         distribution in the manner  mentioned above.  Pledgor  understands that
         the  Administrative  Agent  may in its  discretion  approach  a limited
         number of potential purchasers and that a sale under such circumstances
         may  yield a lower  price  for the  Collateral,  or any  part or  party
         thereof,  than would  otherwise be obtainable if such  collateral  were
         either  afforded  to  a  larger  number  or  potential  purchasers,  or
         registered or sold in the open market. Pledgor agrees that such private
         sale  shall be deemed to have  been made in a  commercially  reasonable
         manner,  and that the  Administrative  Agent has no obligation to delay
         sale of any  Collateral to permit the issuer thereof to register it for
         public sale under any applicable federal or state securities laws.

         The  Administrative  Agent is authorized,  in connection  with any such
         sale (i) to restrict the prospective bidders on or purchasers of any of
         the Collateral to a limited number of sophisticated  investors who will
         represent and agree that they are  purchasing for their own account for
         investment  and not with a view to the  distribution  or sale of any of
         such Collateral and (ii) to impose such other limitations or conditions
         in connection with any such sale as the Administrative Agent reasonably
         deems  necessary  in order  to  comply  with  applicable  law.  Pledgor
         covenants  and agrees that it will execute and deliver  such  documents
         and take such other action as the Administrative Agent reasonably deems
         necessary  in order that any such sale may be made in  compliance  with
         applicable law. Upon any such sale the Administrative  Agent shall have
         the right to deliver,  assign and transfer to the purchaser thereof the
         Collateral  so sold.  Each  purchaser  at any such sale  shall hold the
         Collateral so sold absolutely,  free from any claim or right of Pledgor
         of  whatsoever  kind,  including  any equity or right of  redemption of
         Pledgor.  Pledgor,  to the extent  permitted by applicable  law, hereby
         specifically  waives all rights of redemption,  stay or appraisal which
         it has or may have under any law now existing or hereafter enacted.

         Pledgor   agrees   that  five  (5)  days'   written   notice  from  the
         Administrative Agent to Pledgor of the Administrative Agent's intention
         to make any such public or private sale or sale at a broker's  board or
         on a securities  exchange shall  constitute  "reasonable  notification"
         within the meaning of Section  9-504(c) of the Code.  Such notice shall
         (1) in case of a public  sale,  state the time and place fixed for such
         sale,  (2) in  case  of sale at a  broker's  board  or on a  securities
         exchange,  state the board or  exchange  at which  such a sale is to be
         made and the day on which the  Collateral,  or the  portion  thereof so
         being sold, will first be offered to sale at such board or exchange and
         (3) in the case of a private sale,  state the day after which such sale
         may be consummated.  Any such public sale shall be held at such time or
         times within ordinary business hours and at such place or places as the
         Administrative  Agent may fix in the notice of such  sale.  At any such
         sale,  the  Collateral  may be  sold in one  lot as an  entirety  or in
         separate parcels, as the Administrative Agent may reasonably determine.
         The  Administrative  Agent shall not be obligated to make any such sale
         pursuant to any such  notice.  The  Administrative  Agent may,  without
         notice or publication,  adjourn any public or private sale or cause the
         same to be adjourned from time to time by  announcement at the time and
         place  fixed  for the  sale,  and such  sale may be made at any time or
         place to which the same may be so adjourned.

<PAGE>

         In case of any sale of all or any part of the  Collateral  on credit or
         for future  delivery,  the  Collateral  so sold may be  retained by the
         Administrative  Agent until the selling  price is paid by the purchaser
         thereof,  but the Administrative Agent shall not incur any liability in
         case  of the  failure  of  such  purchaser  to  take up and pay for the
         Collateral so sold and in case of any such failure, such Collateral may
         again be sold upon like notice.  The Administrative  Agent,  instead of
         exercising the power of sale herein conferred upon it, may proceed by a
         suit or suits at law or in equity to foreclose  the Security  Interests
         and sell the Collateral,  or any portion  thereof,  under a judgment or
         decree of a court or courts of competent jurisdiction.

         (b)  Without  the  limiting  the   foregoing,   or  imposing  upon  the
Administrative  Agent any  obligations or duties not required by applicable law,
Pledgor acknowledges and agrees that, in foreclosing upon any of the Collateral,
or exercising  any other rights or remedies  provided the  Administrative  Agent
hereunder or under applicable law, the  Administrative  Agent may, but shall not
be required to (1) qualify or restrict prospective  purchasers of the Collateral
by requiring evidence of sophistication and/or  creditworthiness,  and requiring
the execution and delivery of confidentiality  agreements or other documents and
agreements as a condition to such prospective purchasers' receipt of information
regarding the Collateral or participation  in any public or private  foreclosure
sale process; (2) provide to prospective  purchasers the Partnership  Agreements
and business and financial information  regarding the Partnerships  available in
the files of the Administrative  Agent at the time of commencing the foreclosure
process,  without the requirement that the Administrative  Agent obtain, or seek
to  obtain,  any  updated  business  or  financial  information  or  Partnership
Agreements, or verify, or certify to prospective purchasers, the accuracy of any
such business or financial  information or Partnership  Agreements;  (3) sell at
foreclosure  all, or a portion but not all, of the rights,  titles and interests
of  Pledgor  in a  particular  Partnership  or group of  Partnerships;  it being
further  specifically  acknowledged  by Pledgor  that  limitations  or potential
limitations  on  the  transfer  of  certain  Collateral  under  the  Partnership
Agreements or other  applicable  agreements or law may limit the  Administrative
Agent's right or ability to foreclose  upon or sell certain  rights,  titles and
interests  of  Pledgor  in the  Partnerships;  (4)  offer  for  sale,  and sell,
partnership  interests  either with, or without,  first  employing an appraiser,
investment  banker, or broker with respect to the evaluation of Collateral,  the
solicitation of purchasers for Collateral, or the manner of sale of Collateral.

         (c) The  Administrative  Agent  shall  have all  rights,  remedies  and
recourse  granted in the Loan Agreement and the other Loan Documents or existing
at common law or equity (including  specifically those granted by the Code), and
such rights and  remedies (1) shall be  cumulative  and  concurrent,  (2) may be
pursued separately,  successively or concurrently  against Pledgor and any party
obligated to pay or perform the Obligations, any of the Collateral, or any other
security  for  any  of  the   Obligations,   at  the  sole   discretion  of  the
Administrative  Agent,  and (3) may be exercised  as often as occasion  therefor
shall arise, it being agreed by Pledgor that the exercise or failure to exercise
any such  rights  or  remedies  shall in no event be  construed  as a waiver  or
release thereof or of any other right, remedy or recourse.

         (d)  Notwithstanding  a  foreclosure  upon  any  of the  Collateral  or
exercise of any other remedy by the  Administrative  Agent in connection with an
Event of Default,  Pledgor shall not be subrogated  thereby to any rights of the
Administrative Agent against the Collateral or any other security for any of the
Obligations.  Pledgor shall not be deemed to be the owner of any interest in any
of  the  Obligations  until  all  of  the  Obligations  have  been  paid  to the
Administrative Agent and are fully performed and discharged.

         (e)  All  recitals  in  any  instrument  of  assignment  or  any  other
instrument executed by the Administrative  Agent incident to the sale, transfer,
assignment or other  disposition  or  utilization  of the Collateral or any part
thereof  hereunder  shall be presumptive  evidence of the matters stated therein
and all  prerequisites  of such sale or other action  contained in such recitals
shall be presumed to have been performed or to have occurred.

<PAGE>

         SECTION  5.5  Waivers  by  Pledgor.  In case of any  Event of  Default,
neither Pledgor nor anyone claiming by, through or under Pledgor,  to the extent
Pledgor  may  lawfully  so  agree,  shall or will set up,  claim or seek to take
advantage of any appraisement,  valuation, stay, extension or redemption law now
or hereafter in force in any locality  where any of the  Collateral  is situated
for purposes of applicable law, in order to prevent or hinder the enforcement of
this  Agreement,  or the  absolute  sale of the  Collateral,  or the  final  and
absolute putting into possession  thereof,  immediately  after such sale, of the
purchaser thereof;  and Pledgor in Pledgor's own right and for all who may claim
under Pledgor, hereby waives, to the fullest extent that Pledgor may lawfully do
so, the benefit of any and all right to have the  Collateral  marshaled upon any
enforcement of the Security  Interests  herein granted,  and Pledgor agrees that
the  Administrative  Agent or any  court  having  jurisdiction  to  enforce  the
Security Interests may sell the Collateral in parts or as an entirety.

         SECTION 5.6  Application of Proceeds.  The  Administrative  Agent shall
apply  the  proceeds  of any  foreclosure  sale or  other  realization  upon the
Collateral  as follows  (as  modified,  if  necessary,  by the  requirements  of
applicable law):

         (a) First,  to the payment of all reasonable  costs and expenses of any
foreclosure   and  collection   hereunder  and  all  proceedings  in  connection
therewith, including reasonable compensation to Administrative Agent's counsel;

         (b) Then,  to the  reimbursement  of the  Administrative  Agent for all
disbursements made by the Administrative  Agent for taxes,  assessments or liens
superior to the Security Interests and which the Administrative Agent shall deem
expedient to pay;

     (c) Then, to the  reimbursement of the  Administrative  Agent for any other
disbursements  made by, or reasonable  expenses incurred by, the  Administrative
Agent in accordance with the terms hereof;

     (d) Then,  to the Secured  Indebtedness,  in any manner  determined  by the
Administrative Agent in its sole discretion;

     (e)  Then,  to  the  Refractive  Administrative  Agent  until  all  secured
obligations of Pledgor to it and Refractive Lenders have been paid; and

     (f)      The remainder of such proceeds, if any, shall be paid to Pledgor.

         The foregoing  application  provisions shall apply not only to proceeds
resulting from foreclosure but also to proceeds or distributions  resulting from
any other claim,  (including claims made in bankruptcy  proceedings),  action or
proceeding  to  enforce  or  protect  the  Administrative  Agent's  lien  in the
Collateral.

         SECTION  5.7  Enforcement  of  Secured  Indebtedness.  Nothing  in this
Agreement  shall affect or impair the  unconditional  and absolute  right of the
Administrative  Agent to enforce the Secured  Indebtedness  as and when the same
shall become due in accordance  with the terms of the Loan Documents  whether by
acceleration or otherwise.

<PAGE>

                                   ARTICLE VI

                                  MISCELLANEOUS

         SECTION 6.1 Terms Commercially Reasonable.  The terms of this Agreement
shall be deemed  commercially  reasonable  within  the  meaning  of the  Uniform
Commercial Code in effect and applicable hereto.

         SECTION 6.2 Headings.  The headings of articles and sections herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope or intent of any provision of this Agreement.

         SECTION   6.3   Amendments.   No   change,   amendment,   modification,
cancellation  or discharge of any  provision  of this  Agreement  shall be valid
unless consented to in writing by the Administrative  Agent and Pledgor (subject
to the terms of the Loan Agreement).

         SECTION  6.4  Assignment  of the  Administrative  Agent's  Rights.  The
Administrative  Agent  shall have the right to assign all or any  portion of its
rights  under  this  Agreement  to  any  subsequent  holder  or  holders  of the
Obligations.

         SECTION  6.5 Parties in  Interest.  As and when used  herein,  the term
"Pledgor"  shall mean and include  Pledgor  herein named and his  successors and
permitted assigns,  and the term  "Administrative  Agent" shall mean and include
the  Administrative  Agent herein named and his successors and assigns,  and all
covenants and  agreements  herein shall be binding upon and inure to the benefit
of Pledgor and the Administrative  Agent and their respective assigns,  provided
that  Pledgor  shall have no right to assign his rights  hereunder  to any other
Person  except  in  connection  with  a  transfer  of the  Collateral  permitted
hereunder.

         SECTION  6.6  APPLICABLE  LAWS.  THIS  AGREEMENT  SHALL  BE  CONSTRUED,
INTERPRETED  AND  ENFORCED  UNDER AND PURSUANT TO THE LAWS OF THE STATE OF TEXAS
AND  APPLICABLE  FEDERAL LAW. IF ANY  PROVISION OF THIS  AGREEMENT IS HELD TO BE
INVALID  OR  UNENFORCEABLE,   THE  VALIDITY  AND  ENFORCEABILITY  OF  THE  OTHER
PROVISIONS OF THIS AGREEMENT SHALL REMAIN UNAFFECTED.

         SECTION 6.7 Notices.  Any notices or other  communications  required or
permitted to be given by this Agreement or any other  documents and  instruments
referred  to herein  must be given in  accordance  with  Section  11 of the Loan
Agreement, to the address of such party as follows:

   If to the Administrative Agent:
                                  515 Congress Avenue, 11th Floor
                                  Austin, Texas 78701
                                  Attn: Wade Morgan

                    If to Pledgor:
                                  1301 Capital of Texas Highway
                                  Suite C-300
                                  Austin, Texas 78746-6550
                                  Attn: Treasurer

<PAGE>

         SECTION 6.8  Financing  Statement.  The  Administrative  Agent shall be
entitled  at any  time to file a  photographic  or  other  reproduction  of this
Agreement as a financing statement,  but the failure of the Administrative Agent
to do so shall not impair the validity or enforceability of this Agreement.

         SECTION  6.9  Obligations  Absolute.  All  rights and  remedies  of the
Administrative  Agent hereunder,  and all obligations of the Pledgor  hereunder,
shall be absolute and unconditional irrespective of:

          (a) any lack of validity or  enforceability  of the Loan  Agreement or
     any of the other  Loan  Documents  or any  other  agreement  or  instrument
     relating to any of the foregoing;

          (b) any change in the time,  manner, or place of payment of, or in any
     other term of, all or any of the  Obligations,  or any other  amendment  or
     waiver of or any consent to any departure from the Loan Agreement or any of
     the other Loan Documents;

          (c) any exchange,  release, or nonperfection of any Collateral, or any
     release or  amendment  or waiver of or consent  to any  departure  from any
     guarantee, for all or any of the Obligations; or

                  (d) any other circumstance  (other than payment in full of the
         Obligations) that might otherwise constitute a defense available to, or
         a discharge of, Pledgor.

         SECTION 6.10  Confirmation  of Liens.  Pledgor  acknowledges  that this
Agreement has been given in amendment, renewal, restatement, and confirmation of
Pledgor's  obligations,  covenants,  and agreements  contained in the Pledge and
Security  Agreements  previously  executed by Pledgor in favor of Administrative
Agent and the Lenders, including,  without limitation, that dated April 26, 1996
(the "Previous  Pledge").  Pledgor further  confirms and agrees that neither the
execution of the Loan Agreement or any other Loan Document,  or the consummation
of the transactions described therein, shall in any way affect the liens granted
under the  Previous  Pledge  or the  perfection  or  priority  thereof,  and the
obligations  evidenced by the Previous  Pledge shall  continue in full force and
effect as modified, amended and restated by the terms contained herein.

         SECTION 6.11  Counterparts.  This Agreement may be executed in multiple
counterparts,  each of which shall be deemed to be an original, but all of which
shall  constitute  one and the  same  instrument,  and in  making  proof of this
Agreement it shall not be necessary to produce or account for more than one such
counterpart.

<PAGE>

         SECTION  6.12 ENTIRE  AGREEMENT.  THIS  AGREEMENT  EMBODIES  THE FINAL,
ENTIRE  AGREEMENT  OF  PLEDGOR,  THE  AGENTS  AND THE  LENDERS  WITH  RESPECT TO
PLEDGOR'S PLEDGE OF THE PLEDGED  PARTNERSHIP  INTERESTS AND RESTATES ANY AND ALL
PRIOR COMMITMENTS,  AGREEMENTS,  REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER
WRITTEN OR ORAL,  RELATING TO THE  SUBJECT  MATTER  HEREOF.  THIS  AGREEMENT  IS
INTENDED  BY  PLEDGOR,  THE  AGENTS  AND THE  LENDERS  AS A FINAL  AND  COMPLETE
EXPRESSION  OF THE TERMS OF THIS  AGREEMENT,  AND NO COURSE OF  DEALING  BETWEEN
PLEDGOR,  THE  AGENTS  OR THE  LENDERS,  NO  COURSE  OF  PERFORMANCE,  NO  TRADE
PRACTICES,  AND  NO  EVIDENCE  OF  PRIOR,  CONTEMPORANEOUS  OR  SUBSEQUENT  ORAL
AGREEMENTS OR  DISCUSSIONS  OR OTHER  EXTRINSIC  EVIDENCE OF ANY NATURE SHALL BE
USED TO CONTRADICT, VARY, SUPPLEMENT OR MODIFY ANY TERM OF THIS AGREEMENT. THERE
ARE NO ORAL AGREEMENTS AMONG PLEDGOR, THE AGENTS AND THE LENDERS.

                     [REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGES FOLLOW.]

<PAGE>

                                                   Pledge and Security Agreement

         IN WITNESS  WHEREOF,  Pledgor has executed this Agreement as of the day
and year first above written.

                                    PLEDGOR:

                                                     OHIO LITHO, INC.,
                                                       a Delaware corporation

                                                     By: /s/ Teena E. Belcik
                                                              Teena E. Belcik
                                                              Treasurer

<PAGE>

                                                                       Exhibit A

                                    EXHIBIT A

                                  PARTNERSHIPS

Ohio Mobile Lithotripter, Ltd.

Ohio Mobile Lithotripter II, Ltd.

<PAGE>

                                                                       Exhibit B

                                    EXHIBIT B

                             PARTNERSHIP AGREEMENTS

First  Amended and  Restated  Agreement  of Limited  Partnership  of Ohio Mobile
Lithotripter,  Ltd. dated August 1, 1991, as amended by First Amendment to First
Amended and Restated  Agreement of Limited  Partnership dated as of December 31,
1992

Certificate of Limited Partnership of Ohio Mobile  Lithotripter,  Ltd. dated May
21, 1991

First  Amended and  Restated  Agreement  of Limited  Partnership  of Ohio Mobile
Lithotripter II, Ltd.

Certificate of Limited  Partnership of Ohio Mobile  Lithotripter  II, Ltd. dated
August 23, 1995

                          Pledge and Security Agreement

                          PLEDGE AND SECURITY AGREEMENT

         THIS  PLEDGE  AND  SECURITY  AGREEMENT  (the  "Agreement")  dated as of
January 31,  2000,  is by and between OHIO LITHO,  INC., a Delaware  corporation
("Pledgor"), whose street address is 1301 Capital of Texas Highway, Suite C-300,
Austin, Texas 78746-6550,  for the benefit of BANK OF AMERICA,  N.A., a national
banking association ("B of A"), whose street address is 901 Main Street, Dallas,
Texas 75202, not in its individual  capacity but solely as administrative  agent
for itself and each of the other banks or lending institutions (each, a "Lender"
and collectively, the "Lender") which is or may from time to time become a party
to the Loan Agreement (as hereinbelow defined) (in such capacity,  together with
its successors in such capacity, the "Administrative Agent").

                                R E C I T A L S:

     A.  Prime  Refractive  Management,  L.L.C.,  a Delaware  limited  liability
company  ("Borrower"),  has entered into that certain Loan Agreement dated as of
the date hereof with B of A as Administrative Agent and as a Lender, BankBoston,
N.A., as Documentation Agent and as a Lender, and the other Lenders from time to
time party thereto, as amended,  waived, restated, and supplemented from time to
time ("Loan Agreement").

         B. Pledgor and certain  other  guarantors  have  executed  that certain
Guaranty  Agreement  dated as of the date  hereof  (as the same may be  amended,
supplemented or modified from time to time, the  "Guaranty"),  pursuant to which
Pledgor has guaranteed to the Agents (as defined in the Loan  Agreement) and the
Lenders  the full and  complete  payment  and  performance  of the  liabilities,
obligations,  and  indebtedness  of the  Borrower  to the Agents and the Lenders
under the Loan Documents (as defined in the Loan Agreement).

     C. As a condition to entering into the Loan Agreement, Pledgor must execute
and deliver this Agreement.

         NOW  THEREFORE,  in  consideration  of the  premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, Pledgor agrees with the Administrative Agent as follows:

                                    ARTICLE I

                                   DEFINITIONS

         (a) Each term used herein and defined in the Loan Agreement  shall have
the  meaning  assigned to it in the Loan  Agreement,  unless  otherwise  defined
herein or the context otherwise requires.

         (b) In addition,  as used herein,  the  following  terms shall,  unless
otherwise indicated, have the following meanings:

         "Borrower" has the meaning set forth in the recitals.

         "Code" shall mean the Uniform Commercial Code as in effect in the State
of Texas.

         "Collateral"  shall mean the assets and interests of Pledgor identified
in Section 2.1 hereof.

<PAGE>

                          Pledge and Security Agreement

                                       12

         "Event of  Default"  shall have the  meaning  assigned  to such term in
Section 5.1.

         "Guaranty" shall mean that certain  Guaranty  Agreement dated as of the
date hereof, executed by Pledgor and certain other guarantors for the benefit of
the Agents and the Lenders, guaranteeing the full payment and performance of the
Obligations, as amended, modified, confirmed, and extended from time to time.

         "Partnerships"  shall mean (a) those partnerships and limited liability
companies  listed on  Exhibit  A  attached  hereto  and  incorporated  herein by
reference,  as such  partnerships  or limited  liability  companies exist or may
hereinafter be restated,  amended or restructured,  (b) any  partnership,  joint
venture,  or limited  liability  company in which  Pledgor  shall,  at any time,
become  a  limited  or  general  partner,   venturer,  or  member,  or  (c)  any
partnership, joint venture or corporation formed as a result of the restructure,
reorganization or amendment of the Partnerships.

         "Partnership  Agreements"  shall  mean (a) those  agreements  listed on
Exhibit B attached hereto and  incorporated  herein by reference  (together with
any  modifications,  amendments or  restatements  thereof),  and (b) partnership
agreements,  joint venture agreements,  or organizational  agreements for any of
the partnerships,  joint ventures,  or limited liability  companies described in
clause  (b) of  the  definition  of  "Partnerships"  above  (together  with  any
modifications,  amendments or restatements thereof), and "Partnership Agreement"
means any one of the Partnership Agreements.

         "Pledged Partnership Interests" shall mean all of Pledgor's partnership
interests,  whether general or limited, venture, or membership interests, in the
Partnerships,  including,  without limitation, all of Pledgor's right, title and
interest now or hereafter accruing under the Partnership Agreements with respect
to any  interest  now owned or  hereafter  acquired  or owned by  Pledgor in the
Partnerships,  and including all  distributions,  allocations,  proceeds,  fees,
preferences,  payments or other benefits,  which Pledgor now is or may hereafter
become  entitled to receive with respect to such  interests in the  Partnerships
and with respect to the repayment of all loans now or hereafter  made by Pledgor
to the Partnerships,  and Pledgor's undivided  percentage interest in the assets
of the Partnerships.

         "Secured  Indebtedness" shall have the meaning assigned to such term in
Section 2.1(c) hereof.

         "Security Interests" shall mean the pledge, collateral assignment,  and
security interests securing the Secured  Indebtedness,  including (i) the pledge
and  security  interest in the  Pledged  Partnership  Interests  granted in this
Agreement  and  (ii)  all  other  security  interests  created  or  assigned  as
additional security for the Secured  Indebtedness  pursuant to the provisions of
this Agreement.

         (c) Whenever the context so requires,  the neuter  gender  includes the
masculine and  feminine,  and the singular  number  includes the plural and vice
versa.

<PAGE>

                                   ARTICLE II

                            COLLATERAL AND OBLIGATION

         SECTION 2.1       Grant of Security Interest.
                           --------------------------

         (a) As collateral  security for Secured  Indebtedness,  Pledgor  hereby
pledges and grants to the Administrative  Agent, for the benefit of the Lenders,
a lien on and security  interest in and to, and agrees and acknowledges that the
Administrative Agent has, and shall continue to have, a security interest in and
to, and assigns, transfers, pledges and conveys to the Administrative Agent, all
of  Pledgor's  right,  title  and  interest  in and to the  following  described
collateral (the "Collateral") now owned or hereafter acquired, wherever located,
howsoever  arising or created,  and whether now existing or  hereafter  arising,
existing or created,  subject to a first lien in favor of Bank of America, N.A.,
as Administrative Agent ("Prime  Administrative Agent") under the Fourth Amended
and Restated Loan Agreement  dated the date hereof (the "Prime Loan  Agreement")
among Prime Medical  Services,  Inc., Prime  Administrative  Agent,  BankBoston,
N.A., as  documentation  agent,  and the lenders ("Prime  Lenders") from time to
time thereunder:

                    (i)  the  Pledged  Partnership  Interests  and all rights of
                         Pledgor with respect  thereto and all proceeds,  income
                         and profits therefrom;

                  (ii)     all of Pledgor's  distribution rights, income rights,
                           liquidation  interest,   accounts,  contract  rights,
                           general intangibles,  notes, instruments,  drafts and
                           documents   relating  to  the   Pledged   Partnership
                           Interests;

                  (iii)    to the extent attributable to the Pledged Partnership
                           Interests,  all promissory  notes,  notes receivable,
                           accounts,  accounts  receivable and instruments owned
                           or held by Pledgor or, in which Pledgor owns or holds
                           an   interest,    evidencing   obligations   of   the
                           Partnerships;

                  (iv)     all liens, security interests,  collateral,  property
                           and  assets  securing  any of the  promissory  notes,
                           notes receivables,  instruments,  accounts receivable
                           and other  claims and  interest  described  in clause
                           (iii) above;

                    (v)  all books, files, computer records,  computer software,
                         electronic  information  and other  files,  records  or
                         information  relating  to any or all of the  foregoing;
                         and

                  (vi)     all substitutions,  replacements, products, proceeds,
                           income and profits arising from any of the foregoing;
                           including without limitation insurance proceeds.

         (b)  The  Security   Interests  are  granted  and  the   Collateral  is
collaterally  assigned as security only and shall not subject the Administrative
Agent or any holder of the  Secured  Indebtedness  to, or transfer or in any way
affect or modify,  any obligation or liability of Pledgor with respect to any of
the Collateral.

         (c)  The   Collateral   shall   secure   the   following   obligations,
indebtedness,  and liabilities  (whether at stated maturity,  by acceleration or
otherwise)  (all  such   obligations,   indebtedness,   and  liabilities   being
hereinafter sometimes called the "Secured Indebtedness"):

<PAGE>

                    (i)  the  Obligations and the  obligations,  liabilities and
                         indebtedness  of Pledgor to the Agents and the  Lenders
                         under the Guaranty;

                  (ii)     all reasonable costs and expenses, including, without
                           limitation,  all reasonable attorneys' fees and legal
                           expenses, incurred by any of the Agents or any Lender
                           to preserve and maintain the Collateral,  collect the
                           obligations   herein  described,   and  enforce  this
                           Agreement; and

                    (iii)all extensions,  renewals,  and modifications of any of
                         the foregoing.

         SECTION 2.2 Consent.  To the extent any Partnership  Agreement requires
the consent or agreement of Pledgor to the transfer,  conveyance, or encumbrance
as security  for the Secured  Indebtedness  of all or any portion of the Pledged
Partnership  Interests,  Pledgor hereby irrevocably consents to (a) the grant of
the security  interest  described in Section 2.1 of this Agreement,  and (b) any
transfer or  conveyance  of the Pledged  Partnership  Interests  pursuant to the
Administrative  Agent's exercise of its rights and remedies under Section 5.4 of
this Agreement or under any other Loan Document.

         SECTION 2.3 Pledgor  Remains  Liable.  Notwithstanding  anything to the
contrary contained herein, (a) Pledgor shall remain liable under the Partnership
Agreements  to the  extent set forth  therein  to perform  all of its duties and
obligations  thereunder  to the same  extent as if this  Agreement  had not been
executed  (b) the  exercise  by the  Administrative  Agent of any of its  rights
hereunder shall not release Pledgor from any of its duties or obligations  under
the contracts and  agreements  included in the  Collateral,  and (c) neither the
Administrative Agent nor any Lender shall have any obligation or liability under
the  Partnership  Agreements  by  reason  of  this  Agreement,   nor  shall  the
Administrative  Agent  or  any  Lender  be  obligated  to  perform  any  of  the
obligations or duties of Pledgor  thereunder or to take any action to collect or
enforce any claim for payment assigned hereunder.

                                   ARTICLE III

                         REPRESENTATIONS AND WARRANTIES

         Pledgor hereby represents and warrants to the  Administrative  Agent as
follows:

         (a) Pledgor has good and indefeasible title to the Pledged  Partnership
Interests  and  other  Collateral  free and  clear of any  Lien  except  for the
Security  Interests created by this Agreement and the security interests granted
in favor of Prime  Administrative  Agent,  and has all  necessary  authority  to
pledge and  collaterally  assign the  Pledged  Partnership  Interests  and other
Collateral  as security  for the Secured  Obligations  and such  assignment  and
transfer is not contrary to or in conflict  with the  Partnership  Agreements or
any other agreement;

         (b) No  financing  statement  or other  instrument  similar  in  effect
covering all or any part of the  Collateral is on file in any recording  office,
except such as may have been filed in favor of the Administrative Agent relating
to this Agreement or those in favor of Prime Administrative Agent;

     (c) This  Agreement  has been duly executed and delivered by Pledgor and is
the legal and binding  obligation of Pledgor  enforceable in accordance with its
terms;

<PAGE>

         (d) Upon  execution  of this  Agreement  and an  appropriate  financing
statement  by  Pledgor  and the  recording  of the  financing  statement  in the
appropriate  office,  the  Administrative  Agent  will  have a valid,  perfected
security  interest in the  Collateral,  subject  only to the prior lien of Prime
Administrative Agent;

         (e) Neither the  execution  and  delivery  of this  Agreement,  nor the
consummation of any of the transactions hereby contemplated, nor compliance with
the terms and provisions hereof, will contravene or materially conflict with (i)
any material  provision of law,  statute or  regulation  to which Pledgor or the
Partnerships  is  subject  or  (ii)  any  judgment,  license,  order  or  permit
applicable to Pledgor or the Partnerships.  No consent, approval,  authorization
or  order of any  court,  governmental  authority,  partner  or  third  party is
required that has not been received or taken (i) for the grant by Pledgor of the
Security  Interests,  (ii) for the  execution,  delivery or  performance of this
Agreement by Pledgor,  (iii) for the  perfection of the Security  Interests,  or
(iv) except for such notices as are required by the Code or the Loan  Agreement,
for  the  exercise  by the  Administrative  Agent  of its  rights  and  remedies
hereunder (provided,  however,  that the purchaser of the Collateral at any sale
thereof  pursuant to Section 5.4 hereof may be required to obtain the consent of
the partners in the  Partnerships  and/or satisfy other  conditions set forth in
the Partnership  Agreements prior to such purchaser's  admission as a partner in
the Partnership);

     (f) The chief  executive  office and principal place of business of Pledgor
is in Austin, Travis County, Texas; and

         (g) To the best  knowledge  and belief of  Pledgor,  Pledgor  has fully
performed each and every one of his obligations and duties under the Partnership
Agreements  on or prior to the date due;  Pledgor has not received any notice of
any  default  in  the  performance  of his  obligations  under  the  Partnership
Agreements or of any situation which could give rise to such an event of default
thereunder.

                                   ARTICLE IV

                               PLEDGOR'S COVENANTS

         Pledgor hereby covenants and agrees with the Administrative  Agent that
until the Secured Indebtedness is paid and performed in full:

         (a)  Pledgor  will not cause,  permit or consent  to any  amendment  or
modification  to the  Partnership  Agreements  in effect  as of the date  hereof
except as permitted in the Prime Loan Agreement;

         (b)  Pledgor  will  pay and  discharge  promptly  when  due all  taxes,
assessments,  forced contributions,  governmental charges, fines, penalties, and
any other lawful claims, of every  description,  payable by Pledgor with respect
to (or  which,  if not paid  could  result  in an  encumbrance  upon) any of the
Collateral, except as otherwise permitted by the terms of the Loan Agreement. In
the  event  that  Pledgor  should,  for any  reason,  fail to pay and  discharge
promptly any taxes,  assessments,  forced  contributions,  governmental charges,
fines,  or  penalties  when due  (subject  to the  provisions  of the Prime Loan
Agreement),  then the Administrative Agent shall be authorized, but shall not be
obligated, to pay the same, with full subrogation to all rights of any Person by
reason of such payment,  and the amounts so paid, together with interest thereon
as provided herein, shall be secured by the Security Interests;

<PAGE>

         (c) Pledgor will not sell, transfer, mortgage or otherwise encumber any
Collateral  in any manner,  except for the  security  interest in favor of Prime
Administrative  Agent,  without  first  obtaining  the  written  consent  of the
Administrative  Agent. Any written consent to any such sale, mortgage,  transfer
or  encumbrance  shall  not be  construed  to be a waiver of this  provision  in
respect of any subsequent proposed sale, mortgage, transfer or encumbrance;

         (d)  Pledgor  will,  at its  expense and in such manner and form as the
Administrative Agent may from time to time reasonably require, execute, deliver,
file  and  record  any  financing   statement,   specific  assignment  or  other
instruments,  certificates  or  papers  and take any  other  action  that may be
necessary or desirable,  or that the Administrative  Agent may from time to time
reasonably  request,  in order to  create,  preserve,  perfect or  validate  any
Security Interest or to enable the Administrative  Agent to exercise and enforce
its rights  hereunder with respect to any of the Collateral.  In the event,  for
any  reason,  that the law of any  jurisdiction  other  than the  State of Texas
becomes or is applicable to the Collateral,  or any part thereof, Pledgor agrees
to execute and deliver all such instruments and to do all such other things that
may be necessary or  appropriate  to preserve,  protect and enforce the Security
Interests of the Administrative  Agent under the law of such other jurisdiction,
to at least the same extent that the Security Interests would be protected under
the Code. To the extent permitted by applicable law,  Pledgor hereby  authorizes
the  Administrative  Agent  to  execute  and  file,  in the name of  Pledgor  or
otherwise,  Uniform Commercial Code financing statements that the Administrative
Agent in its sole  discretion  may deem  necessary  or  appropriate  to  further
perfect the Security Interests;

         (e) If Pledgor receives,  by virtue of being or having been an owner of
any of the Collateral, any notes, other instruments, options, cash distributions
or any other distribution,  resulting from a Capital Event (hereinafter defined)
Pledgor  shall  receive the same in trust for the benefit of the  Administrative
Agent,  shall immediately  notify the  Administrative  Agent of such receipt and
shall  immediately  take all such actions and execute all such  documents as the
Administrative  Agent deems  necessary or  appropriate  to continue or create as
perfected Liens, in favor of the Administrative Agent covering such notes, other
instruments, options, cash distributions, subject ony to the prior lien in favor
of the Prime  Administrative  Agent.  As used herein,  the term "Capital  Event"
shall mean any event generating or resulting in revenues not attributable to the
normal business operations of the Partnerships including without limitation, any
mortgaging of assets,  refinancing of existing  indebtedness of any Partnership,
condemnation of any assets of any Partnership, sale or transfer of any assets of
any Partnership outside the ordinary course of business, or payment of insurance
proceeds. At all times other than during the continuance of an Event of Default,
Pledgor shall be entitled to receive free from the security  interest hereof any
note, other  instrument,  option,  cash  distribution or any other  distribution
resulting from any event other than a Capital Event;

         (f) Pledgor will notify the  Administrative  Agent in writing  prior to
the removal of Pledgor's chief  executive  office or principal place of business
from the State of Texas;

         (g) Pledgor shall cause to be obtained any and all waivers and consents
necessary to make  effective the grant  contained in and to perfect the security
interest  granted to the  Administrative  Agent  pursuant to Section 2.1 hereof,
including without limitation,  all necessary waivers and consents from the other
partners, if any, of each Partnership;

         (h) Pledgor shall perform fully all obligations  imposed upon it by any
agreements  or  instruments  concerning  all or  any  part  of  the  Collateral,
including  without  limitation the Partnership  Agreements and shall maintain in
full force and effect all such agreements and  instruments,  and shall not amend
or modify,  or consent to the amendment or  modification  of such  agreements or
instruments, without the prior written consent of the Administrative Agent; and

<PAGE>

         (i)  Pledgor  shall  promptly  notify the  Administrative  Agent of any
material adverse change in any material fact or material circumstance  warranted
or represented by Pledgor in this Agreement or in any other writing furnished by
Pledgor to the  Administrative  Agent in connection  with the  Collateral or the
Secured Indebtedness,  and shall promptly notify the Administrative Agent of any
claim,  action or  proceeding  affecting  title to the  Collateral,  or any part
thereof,  or  the  Security  Interests  herein,  and,  at  the  request  of  the
Administrative  Agent, shall appear and defend, at Pledgor's  expense,  any such
action or proceeding.

                                    ARTICLE V

                    GENERAL AUTHORITY AND POWERS AND REMEDIES

         SECTION 5.1       Events of Default.
                           -----------------

         Pledgor shall be in default under this  Agreement upon the happening of
any of the  following  events  or  conditions  (hereinafter  called an "Event of
Default"):

         (a)      An Event of Default under the Loan Agreement shall occur; or

     (b) The ownership of any of the  Collateral  becomes  vested in a person or
entity other than Pledgor, except as permitted hereunder; or

         (c) The  Administrative  Agent's Liens in any of the Collateral  should
become  unenforceable,  or cease to be first priority Liens, subject only to the
prior lien of Prime Administrative Agent.

         SECTION 5.2 Right to Receive  Distributions.  The Administrative  Agent
shall  have the  right,  at any time  following  the  occurrence  and during the
continuation of an Event of Default,  to receive all payments and  distributions
made to Pledgor upon or with  respect to the  Collateral  and Pledgor  agrees to
take all such action as the  Administrative  Agent may reasonably deem necessary
or appropriate to give effect to such right.

         SECTION 5.3 General Authority.  Pledgor hereby irrevocably appoints the
Administrative  Agent,  and its  successors  and  assigns,  the true and  lawful
attorney-in-fact  of Pledgor,  with full power of  substitution,  in the name of
Pledgor,  for the sole  use and  benefit  of the  Administrative  Agent,  but at
Pledgor's expense,  to the extent permitted by law to exercise,  at any time and
from time to time  following the  occurrence  and during the  continuance  of an
Event of Default,  all or any of the following powers with respect to all or any
of the Collateral:

     (a) to ask,  demand,  sue for,  collect,  receive and give  acquittance and
receipts for any and all monies due or to become due upon or by virtue thereof;

     (b) to  receive,  endorse,  and  collect  any drafts or other  instruments,
documents and chattel paper, in connection with clause (a) preceding;

     (c) to  settle,  compromise,  compound,  prosecute  or defend any action or
proceeding with respect thereto;

         (d)  subject  to  Section  5.4  hereof,  to sell,  transfer,  assign or
otherwise  deal in or with  the  same  or the  proceeds  thereof  as  fully  and
effectually as if the Administrative Agent were the absolute owner thereof; and

<PAGE>

     (e) to extend  the time of payment  of any or all  thereof  and to make any
allowance and other adjustments with reference thereto.

In addition,  the  Administrative  Agent, at any time, either before or after an
Event of Default, shall have the right, together with such accountants and other
agents or representatives as they may from time to time designate,  to visit and
inspect the Partnerships'  properties,  assets, books, records and documents and
to discuss the Partnerships'  affairs,  finances and accounts with Pledgor's and
the Partnerships'  representatives,  officers or directors,  during all business
hours as the  Administrative  Agent  may  designate,  and to make and take  away
copies of the  Partnerships'  records  at the  Administrative  Agent's  expense.
Pledgor  shall  furnish  to  Administrative  Agent  any  information  reasonably
requested by the Administrative Agent in connection with the Collateral. Pledgor
will maintain complete and accurate books and records regarding the Collateral.

         SECTION 5.4       Remedies Upon Default.
                           ---------------------

         (a) If any Event of Default shall have occurred and is continuing,  the
Administrative  Agent,  at its option,  without demand,  presentment,  notice of
acceleration,  intention to  accelerate or other notice (which are fully waived)
may:

                  (1) exercise all the rights of a secured  party under the Code
         (whether  or not the Code is in effect in the  jurisdiction  where such
         rights are exercise, unless prohibited by applicable law).

     (2) apply  the  cash,  if any,  then  held by the  Administrative  Agent as
Collateral as specified in Section 5.6.

                  (3) sell all of the  Collateral  or any part thereof at public
         or private sale or at any broker's board or on any securities exchange,
         for cash,  upon  credit or for  future  delivery,  and at such price or
         prices as the  Administrative  Agent may reasonably deem  satisfactory.
         Upon the  Administrative  Agent's  demand,  Pledgor will take all steps
         necessary to prepare the  Collateral  for and  otherwise  assist in any
         proposed  disposition  of the  Collateral.  Any  holder of the  Secured
         Indebtedness  may be the  purchaser of any or all of the  Collateral so
         sold at any public sale (or, if the Collateral is of a type customarily
         sold in a  recognized  market or is of a type  which is the  subject of
         widely distributed standard price quotations,  at any private sale) and
         thereafter  hold the same  absolutely,  free from any right or claim of
         whatsoever kind. Any holder of the Secured  Indebtedness shall have the
         right to offset  the amount of its bid  against an equal  amount of the
         Secured Indebtedness held by such holder.

<PAGE>

         Pledgor agrees that, because of the Securities Act of 1933, as amended,
         or any other laws or regulations,  and for other reasons,  there may be
         legal  and/or  practical  restrictions  or  limitations  affecting  the
         Administrative  Agent in any attempts to dispose of certain portions of
         the  Collateral  and for the  enforcement  of their  rights.  For these
         reasons,  the Administrative Agent is hereby authorized by Pledgor, but
         not obligated,  upon the occurrence and during the  continuation  of an
         Event of Default,  to sell all or any part of the Collateral at private
         sale,  subject to  investment  letter or in any other manner which will
         not require the  Collateral,  or any part thereof,  to be registered in
         accordance  with the Securities  Act of 1933, as amended,  or the rules
         and  regulations   promulgated   thereunder,   or  any  other  laws  or
         regulations,  at a  reasonable  price  at such  private  sale or  other
         distribution in the manner  mentioned above.  Pledgor  understands that
         the  Administrative  Agent  may in its  discretion  approach  a limited
         number of potential purchasers and that a sale under such circumstances
         may  yield a lower  price  for the  Collateral,  or any  part or  party
         thereof,  than would  otherwise be obtainable if such  collateral  were
         either  afforded  to  a  larger  number  or  potential  purchasers,  or
         registered or sold in the open market. Pledgor agrees that such private
         sale  shall be deemed to have  been made in a  commercially  reasonable
         manner,  and that the  Administrative  Agent has no obligation to delay
         sale of any  Collateral to permit the issuer thereof to register it for
         public sale under any applicable federal or state securities laws.

         The  Administrative  Agent is authorized,  in connection  with any such
         sale (i) to restrict the prospective bidders on or purchasers of any of
         the Collateral to a limited number of sophisticated  investors who will
         represent and agree that they are  purchasing for their own account for
         investment  and not with a view to the  distribution  or sale of any of
         such Collateral and (ii) to impose such other limitations or conditions
         in connection with any such sale as the Administrative Agent reasonably
         deems  necessary  in order  to  comply  with  applicable  law.  Pledgor
         covenants  and agrees that it will execute and deliver  such  documents
         and take such other action as the Administrative Agent reasonably deems
         necessary  in order that any such sale may be made in  compliance  with
         applicable law. Upon any such sale the Administrative  Agent shall have
         the right to deliver,  assign and transfer to the purchaser thereof the
         Collateral  so sold.  Each  purchaser  at any such sale  shall hold the
         Collateral so sold absolutely,  free from any claim or right of Pledgor
         of  whatsoever  kind,  including  any equity or right of  redemption of
         Pledgor.  Pledgor,  to the extent  permitted by applicable  law, hereby
         specifically  waives all rights of redemption,  stay or appraisal which
         it has or may have under any law now existing or hereafter enacted.

         Pledgor   agrees   that  five  (5)  days'   written   notice  from  the
         Administrative Agent to Pledgor of the Administrative Agent's intention
         to make any such public or private sale or sale at a broker's  board or
         on a securities  exchange shall  constitute  "reasonable  notification"
         within the meaning of Section  9-504(c) of the Code.  Such notice shall
         (1) in case of a public  sale,  state the time and place fixed for such
         sale,  (2) in  case  of sale at a  broker's  board  or on a  securities
         exchange,  state the board or  exchange  at which  such a sale is to be
         made and the day on which the  Collateral,  or the  portion  thereof so
         being sold, will first be offered to sale at such board or exchange and
         (3) in the case of a private sale,  state the day after which such sale
         may be consummated.  Any such public sale shall be held at such time or
         times within ordinary business hours and at such place or places as the
         Administrative  Agent may fix in the notice of such  sale.  At any such
         sale,  the  Collateral  may be  sold in one  lot as an  entirety  or in
         separate parcels, as the Administrative Agent may reasonably determine.
         The  Administrative  Agent shall not be obligated to make any such sale
         pursuant to any such  notice.  The  Administrative  Agent may,  without
         notice or publication,  adjourn any public or private sale or cause the
         same to be adjourned from time to time by  announcement at the time and
         place  fixed  for the  sale,  and such  sale may be made at any time or
         place to which the same may be so adjourned.

         In case of any sale of all or any part of the  Collateral  on credit or
         for future  delivery,  the  Collateral  so sold may be  retained by the
         Administrative  Agent until the selling  price is paid by the purchaser
         thereof,  but the Administrative Agent shall not incur any liability in
         case  of the  failure  of  such  purchaser  to  take up and pay for the
         Collateral so sold and in case of any such failure, such Collateral may
         again be sold upon like notice.  The Administrative  Agent,  instead of
         exercising the power of sale herein conferred upon it, may proceed by a
         suit or suits at law or in equity to foreclose  the Security  Interests
         and sell the Collateral,  or any portion  thereof,  under a judgment or
         decree of a court or courts of competent jurisdiction.

<PAGE>

         (b)  Without  the  limiting  the   foregoing,   or  imposing  upon  the
Administrative  Agent any  obligations or duties not required by applicable law,
Pledgor acknowledges and agrees that, in foreclosing upon any of the Collateral,
or exercising  any other rights or remedies  provided the  Administrative  Agent
hereunder or under applicable law, the  Administrative  Agent may, but shall not
be required to (1) qualify or restrict prospective  purchasers of the Collateral
by requiring evidence of sophistication and/or  creditworthiness,  and requiring
the execution and delivery of confidentiality  agreements or other documents and
agreements as a condition to such prospective purchasers' receipt of information
regarding the Collateral or participation  in any public or private  foreclosure
sale process; (2) provide to prospective  purchasers the Partnership  Agreements
and business and financial information  regarding the Partnerships  available in
the files of the Administrative  Agent at the time of commencing the foreclosure
process,  without the requirement that the Administrative  Agent obtain, or seek
to  obtain,  any  updated  business  or  financial  information  or  Partnership
Agreements, or verify, or certify to prospective purchasers, the accuracy of any
such business or financial  information or Partnership  Agreements;  (3) sell at
foreclosure  all, or a portion but not all, of the rights,  titles and interests
of  Pledgor  in a  particular  Partnership  or group of  Partnerships;  it being
further  specifically  acknowledged  by Pledgor  that  limitations  or potential
limitations  on  the  transfer  of  certain  Collateral  under  the  Partnership
Agreements or other  applicable  agreements or law may limit the  Administrative
Agent's right or ability to foreclose  upon or sell certain  rights,  titles and
interests  of  Pledgor  in the  Partnerships;  (4)  offer  for  sale,  and sell,
partnership  interests  either with, or without,  first  employing an appraiser,
investment  banker, or broker with respect to the evaluation of Collateral,  the
solicitation of purchasers for Collateral, or the manner of sale of Collateral.

         (c) The  Administrative  Agent  shall  have all  rights,  remedies  and
recourse  granted in the Loan Agreement and the other Loan Documents or existing
at common law or equity (including  specifically those granted by the Code), and
such rights and  remedies (1) shall be  cumulative  and  concurrent,  (2) may be
pursued separately,  successively or concurrently  against Pledgor and any party
obligated to pay or perform the Obligations, any of the Collateral, or any other
security  for  any  of  the   Obligations,   at  the  sole   discretion  of  the
Administrative  Agent,  and (3) may be exercised  as often as occasion  therefor
shall arise, it being agreed by Pledgor that the exercise or failure to exercise
any such  rights  or  remedies  shall in no event be  construed  as a waiver  or
release thereof or of any other right, remedy or recourse.

         (d)  Notwithstanding  a  foreclosure  upon  any  of the  Collateral  or
exercise of any other remedy by the  Administrative  Agent in connection with an
Event of Default,  Pledgor shall not be subrogated  thereby to any rights of the
Administrative Agent against the Collateral or any other security for any of the
Obligations.  Pledgor shall not be deemed to be the owner of any interest in any
of  the  Obligations  until  all  of  the  Obligations  have  been  paid  to the
Administrative Agent and are fully performed and discharged.

         (e)  All  recitals  in  any  instrument  of  assignment  or  any  other
instrument executed by the Administrative  Agent incident to the sale, transfer,
assignment or other  disposition  or  utilization  of the Collateral or any part
thereof  hereunder  shall be presumptive  evidence of the matters stated therein
and all  prerequisites  of such sale or other action  contained in such recitals
shall be presumed to have been performed or to have occurred.

<PAGE>

         SECTION  5.5  Waivers  by  Pledgor.  In case of any  Event of  Default,
neither Pledgor nor anyone claiming by, through or under Pledgor,  to the extent
Pledgor  may  lawfully  so  agree,  shall or will set up,  claim or seek to take
advantage of any appraisement,  valuation, stay, extension or redemption law now
or hereafter in force in any locality  where any of the  Collateral  is situated
for purposes of applicable law, in order to prevent or hinder the enforcement of
this  Agreement,  or the  absolute  sale of the  Collateral,  or the  final  and
absolute putting into possession  thereof,  immediately  after such sale, of the
purchaser thereof;  and Pledgor in Pledgor's own right and for all who may claim
under Pledgor, hereby waives, to the fullest extent that Pledgor may lawfully do
so, the benefit of any and all right to have the  Collateral  marshaled upon any
enforcement of the Security  Interests  herein granted,  and Pledgor agrees that
the  Administrative  Agent or any  court  having  jurisdiction  to  enforce  the
Security Interests may sell the Collateral in parts or as an entirety.

         SECTION 5.6  Application of Proceeds.  The  Administrative  Agent shall
apply  the  proceeds  of any  foreclosure  sale or  other  realization  upon the
Collateral  as follows  (as  modified,  if  necessary,  by the  requirements  of
applicable law):

         (a) First,  to the payment of all reasonable  costs and expenses of any
foreclosure   and  collection   hereunder  and  all  proceedings  in  connection
therewith, including reasonable compensation to Administrative Agent's counsel;

         (b) Then,  to the  reimbursement  of the  Administrative  Agent for all
disbursements made by the Administrative  Agent for taxes,  assessments or liens
superior to the Security Interests and which the Administrative Agent shall deem
expedient to pay;

     (c) Then, to the  reimbursement of the  Administrative  Agent for any other
disbursements  made by, or reasonable  expenses incurred by, the  Administrative
Agent in accordance with the terms hereof;

     (d) Then, to the Prime  Administrative  Agent until all secured obligations
of Pledgor to it and the Prime Lenders are paid;

     (e) Then,  to the Secured  Indebtedness,  in any manner  determined  by the
Administrative Agent in its sole discretion; and

     (f) The remainder of such proceeds, if any, shall be paid to Pledgor.

         The foregoing  application  provisions shall apply not only to proceeds
resulting from foreclosure but also to proceeds or distributions  resulting from
any other claim,  (including claims made in bankruptcy  proceedings),  action or
proceeding  to  enforce  or  protect  the  Administrative  Agent's  lien  in the
Collateral.

         SECTION  5.7  Enforcement  of  Secured  Indebtedness.  Nothing  in this
Agreement  shall affect or impair the  unconditional  and absolute  right of the
Administrative  Agent to enforce the Secured  Indebtedness  as and when the same
shall become due in accordance  with the terms of the Loan Documents  whether by
acceleration or otherwise.

                                   ARTICLE VI

                                  MISCELLANEOUS

         SECTION 6.1 Terms Commercially Reasonable.  The terms of this Agreement
shall be deemed  commercially  reasonable  within  the  meaning  of the  Uniform
Commercial Code in effect and applicable hereto.

         SECTION 6.2 Headings.  The headings of articles and sections herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope or intent of any provision of this Agreement.

<PAGE>

         SECTION   6.3   Amendments.   No   change,   amendment,   modification,
cancellation  or discharge of any  provision  of this  Agreement  shall be valid
unless consented to in writing by the Administrative  Agent and Pledgor (subject
to the terms of the Loan Agreement).

         SECTION  6.4  Assignment  of the  Administrative  Agent's  Rights.  The
Administrative  Agent  shall have the right to assign all or any  portion of its
rights  under  this  Agreement  to  any  subsequent  holder  or  holders  of the
Obligations.

         SECTION  6.5 Parties in  Interest.  As and when used  herein,  the term
"Pledgor"  shall mean and include  Pledgor  herein named and his  successors and
permitted assigns,  and the term  "Administrative  Agent" shall mean and include
the  Administrative  Agent herein named and his successors and assigns,  and all
covenants and  agreements  herein shall be binding upon and inure to the benefit
of Pledgor and the Administrative  Agent and their respective assigns,  provided
that  Pledgor  shall have no right to assign his rights  hereunder  to any other
Person  except  in  connection  with  a  transfer  of the  Collateral  permitted
hereunder.

         SECTION  6.6  APPLICABLE  LAWS.  THIS  AGREEMENT  SHALL  BE  CONSTRUED,
INTERPRETED  AND  ENFORCED  UNDER AND PURSUANT TO THE LAWS OF THE STATE OF TEXAS
AND  APPLICABLE  FEDERAL LAW. IF ANY  PROVISION OF THIS  AGREEMENT IS HELD TO BE
INVALID  OR  UNENFORCEABLE,   THE  VALIDITY  AND  ENFORCEABILITY  OF  THE  OTHER
PROVISIONS OF THIS AGREEMENT SHALL REMAIN UNAFFECTED.

         SECTION 6.7 Notices.  Any notices or other  communications  required or
permitted to be given by this Agreement or any other  documents and  instruments
referred  to herein  must be given in  accordance  with  Section  11 of the Loan
Agreement, to the address of such party as follows:

         If to the Administrative Agent:       515 Congress Avenue, 11th Floor

                                               Austin, Texas 78701

                                               Attn: Wade Morgan

         If to Pledgor:                        1301 Capital of Texas Highway

                                               Suite C-300

                                               Austin, Texas 78746-6550

                                               Attn: Treasurer

         SECTION 6.8  Financing  Statement.  The  Administrative  Agent shall be
entitled  at any  time to file a  photographic  or  other  reproduction  of this
Agreement as a financing statement,  but the failure of the Administrative Agent
to do so shall not impair the validity or enforceability of this Agreement.

         SECTION  6.9  Obligations  Absolute.  All  rights and  remedies  of the
Administrative  Agent hereunder,  and all obligations of the Pledgor  hereunder,
shall be absolute and unconditional irrespective of:

               (a) any lack of validity or  enforceability of the Loan Agreement
          or any  of  the  other  Loan  Documents  or  any  other  agreement  or
          instrument relating to any of the foregoing;

                  (b) any change in the time, manner, or place of payment of, or
         in any  other  term of,  all or any of the  Obligations,  or any  other
         amendment  or waiver of or any consent to any  departure  from the Loan
         Agreement or any of the other Loan Documents;

<PAGE>

               (c) any exchange, release, or nonperfection of any Collateral, or
          any release or amendment or waiver of or consent to any departure from
          any guarantee, for all or any of the Obligations; or

                  (d) any other circumstance  (other than payment in full of the
         Obligations) that might otherwise constitute a defense available to, or
         a discharge of, Pledgor.

         SECTION 6.10  Counterparts.  This Agreement may be executed in multiple
counterparts,  each of which shall be deemed to be an original, but all of which
shall  constitute  one and the  same  instrument,  and in  making  proof of this
Agreement it shall not be necessary to produce or account for more than one such
counterpart.

         SECTION  6.11 ENTIRE  AGREEMENT.  THIS  AGREEMENT  EMBODIES  THE FINAL,
ENTIRE  AGREEMENT  OF  PLEDGOR,  THE  AGENTS  AND THE  LENDERS  WITH  RESPECT TO
PLEDGOR'S PLEDGE OF THE PLEDGED  PARTNERSHIP  INTERESTS AND RESTATES ANY AND ALL
PRIOR COMMITMENTS,  AGREEMENTS,  REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER
WRITTEN OR ORAL,  RELATING TO THE  SUBJECT  MATTER  HEREOF.  THIS  AGREEMENT  IS
INTENDED  BY  PLEDGOR,  THE  AGENTS  AND THE  LENDERS  AS A FINAL  AND  COMPLETE
EXPRESSION  OF THE TERMS OF THIS  AGREEMENT,  AND NO COURSE OF  DEALING  BETWEEN
PLEDGOR,  THE  AGENTS  OR THE  LENDERS,  NO  COURSE  OF  PERFORMANCE,  NO  TRADE
PRACTICES,  AND  NO  EVIDENCE  OF  PRIOR,  CONTEMPORANEOUS  OR  SUBSEQUENT  ORAL
AGREEMENTS OR  DISCUSSIONS  OR OTHER  EXTRINSIC  EVIDENCE OF ANY NATURE SHALL BE
USED TO CONTRADICT, VARY, SUPPLEMENT OR MODIFY ANY TERM OF THIS AGREEMENT. THERE
ARE NO ORAL AGREEMENTS AMONG PLEDGOR, THE AGENTS AND THE LENDERS.

                     [REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGES FOLLOW.]

<PAGE>

                          Pledge and Security Agreement

         IN WITNESS  WHEREOF,  Pledgor has executed this Agreement as of the day
and year first above written.

                                    PLEDGOR:

                                                     OHIO LITHO, INC.,
                                                       a Delaware corporation

                                                     By: /s/ Teena E. Belcik
                                                              Teena E. Belcik
                                                              Treasurer

<PAGE>

                                                                       Exhibit A

                                    EXHIBIT A

                                  PARTNERSHIPS

Ohio Mobile Lithotripter, Ltd.

Ohio Mobile Lithotripter II, Ltd.

<PAGE>

                                                                       Exhibit B

                                    EXHIBIT B

                             PARTNERSHIP AGREEMENTS

First  Amended and  Restated  Agreement  of Limited  Partnership  of Ohio Mobile
Lithotripter,  Ltd. dated August 1, 1991, as amended by First Amendment to First
Amended and Restated  Agreement of Limited  Partnership dated as of December 31,
1992

Certificate of Limited Partnership of Ohio Mobile  Lithotripter,  Ltd. dated May
21, 1991

First  Amended and  Restated  Agreement  of Limited  Partnership  of Ohio Mobile
Lithotripter II, Ltd.

Certificate of Limited  Partnership of Ohio Mobile  Lithotripter  II, Ltd. dated
August 23, 1995

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00005-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00005-of-00352.parquet"}]]