Document:

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                                                                   EXHIBIT 10.12

                                PROMISSORY NOTE

U.S. $1,200,000.00                                             November 12, 1998

              FOR VALUE RECEIVED, the undersigned, KELLY D. CONWAY, of [Home
Address] ("Borrower"), hereby unconditionally promises to pay to the order of
TECHNOLOGY SOLUTIONS COMPANY, a Delaware Corporation ("Lender"), having its
principal office at 205 North Michigan Avenue, Chicago, Illinois 60601, in
lawful money of the United States of America and in immediately available funds,
the principal sum of ONE MILLION TWO HUNDRED THOUSAND DOLLARS AND NO CENTS
($1,200,000.00), together with interest on the principal and accrued interest
balance from time to time outstanding at the rate of FOUR AND FIFTY-ONE
HUNDREDTHS percent (4.51%) per annum from the date hereof until payment in full
on November 12, 2003 (the "Payment Date") in accordance with this Promissory
Note; provided, however, that:

              (i) if Borrower has been employed by Lender, or any parent or
subsidiary company of Lender, from the date hereof through and including
November 12, 1999 (the "First Anniversary Date"), then the amount of three
hundred thousand dollars ($300,000.00) of outstanding principal indebtedness,
plus interest accrued on such amount, shall be discharged and forgiven by Lender
and shall no longer be due and, accordingly, Borrower shall have no further
obligation to Lender hereunder; and

              (ii) if Borrower has been employed by Lender, or any parent or
subsidiary company of Lender, from the date hereof through and including the
twelfth day of each calendar month following the First Anniversary Date, then on
each such twelfth day of each calendar month following the First Anniversary
Date, up to November 12, 2000 (the "Second Anniversary Date"), the amount of
twenty five thousand dollars ($25,000.00) of outstanding principal indebtedness,
plus interest accrued on such amount, shall be discharged and forgiven by Lender
and shall no longer be due and, accordingly, Borrower shall have no further
obligation to Lender hereunder; and

              (iii) if Borrower has been employed by Lender, or any parent or
subsidiary company of Lender, from the date hereof through and including the
twelfth day of each calendar month following the Second Anniversary Date, then
on each such twelfth day of each calendar month following the Second Anniversary
Date, up to November 12, 2001 (the "Third Anniversary Date"), the amount of
twenty thousand dollars ($20,000.00) of outstanding principal indebtedness, plus
interest accrued on such amount, shall be discharged and forgiven by Lender and
shall no longer be due and, accordingly, Borrower shall have no further
obligation to Lender hereunder; and

              (iv) if Borrower has been employed by Lender, or any parent or
subsidiary company of Lender, from the date hereof through and including the
twelfth day of each calendar month following the Third Anniversary Date, then on
each such twelfth day of

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each calendar month following the Third Anniversary Date, up to November 12,
2002 (the "Fourth Anniversary Date"), the amount of twenty thousand dollars
($20,000.00) of outstanding principal indebtedness, plus interest accrued on
such amount, shall be discharged and forgiven by Lender and shall no longer be
due and, accordingly, Borrower shall have no further obligation to Lender
hereunder; and

              (v) if Borrower has been employed by Lender, or any parent or
subsidiary company of Lender, from the date hereof through and including the
twelfth day of each calendar month following the Fourth Anniversary Date, then
on each such twelfth day of each calendar month following the Fourth Anniversary
Date, up to the Payment Date, the amount of ten thousand dollars ($10,000.00) of
outstanding principal indebtedness, plus interest accrued on such amount, shall
be discharged and forgiven by Lender and shall no longer be due and,
accordingly, Borrower shall have no further obligation to Lender hereunder.

              (vi) if Borrower has been employed by Lender, or any parent or
subsidiary company of Lender, from the date hereof through and including the
Payment Date, then any and all amounts of remaining outstanding interest accrued
hereunder shall be discharged and forgiven by Lender and shall no longer be due
and, accordingly, Borrower shall have no further obligation to Lender hereunder.

              Borrower, however, shall be responsible for income tax on the
principal plus interest, if and when they are recognized as income, which shall
be withheld by Lender from any amounts owed by Lender to Borrower, including
payroll.

              Borrower reserves the right to prepay this Note, in whole or in
part, at any time without penalty. In the event of such prepayment, the amount
so prepaid will be applied to principal due and interest will be adjusted
accordingly.

              All payments of principal and interest under this Note shall be
made by Borrower to Lender, at Lender's principal place of business as set forth
above, or at such other place as Lender may from time to time designate in
writing.

              The occurrence or existence of one or more of the following events
shall constitute an event of default ("Default") under this Note: (i) the
failure of Borrower to pay when due any principal or interest due hereunder; or
(ii) (a) Borrower shall become generally unable to pay his debts as they become
due, or (b) Borrower shall make an assignment for the benefit of creditors, or
(c) Borrower shall call a meeting of creditors for the composition of debts, or
(d) a proceeding under any bankruptcy, reorganization, arrangement of debt,
insolvency, readjustment of debt or receivership law or statute is filed by or
against Borrower, or a custodian, receiver or agent is appointed or authorized
to take charge of any of Borrower's properties, or Borrower takes any action to
authorize any of the foregoing; or (iii) Borrower shall no longer remain, for
any reason, an employee of Lender, or a parent or subsidiary company of Lender,
or (v) there shall be entered against Borrower any judgment or judgments in an
aggregate amount in excess of

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$100,000, unless the amounts of such judgment or judgments are covered by
insurance and liability under such insurance has been admitted by the issuer
thereof.

              In an event of Default, Lender may, by notice to Borrower, declare
all the indebtedness evidenced by this Note to be, and thereupon such
indebtedness shall become, immediately due and payable, without presentment,
demand, protest or further notice of any kind, all of which are hereby expressly
waived by Borrower; provided, however, that if the Default specified in clause
(ii) (d) in the paragraph two paragraphs above occurs, the indebtedness
evidenced by this Note shall automatically become due and payable, without
presentment, demand, protest or any notice of any kind, all of which are hereby
expressly waived by Borrower.

              If payment hereunder becomes due and payable on a day which is not
a "Business Day" (as defined below), the due date thereof shall be extended to
the next succeeding Business Day, and interest shall be payable thereon during
such extension at the rate specified above. "Business Day" shall mean a day on
which banks in Chicago, Illinois are open for the transaction of banking
business. In no case or event whatsoever shall interest charged hereunder,
however such interest may be characterized or computed, exceed the highest rate
permissible under any law which a court of competent jurisdiction shall, in a
final determination, deem applicable hereto. In the event that such a court
determines that Lender has received interest hereunder in excess of the highest
rate applicable hereto, Lender shall (i) apply such excess to any unpaid
principal balance due and payable by Borrower hereunder to Lender; and (ii) if
the amount of such excess exceeds the unpaid principal and other liabilities due
and payable by Borrower hereunder, Lender shall remit such excess to Borrower.

              Any notice hereunder shall be sufficiently given if in writing and
delivered in person or mailed by first class mail addressed as follows:

              IF TO BORROWER:

              Kelly D. Conway
              [Home Address]

              IF TO LENDER:

              Technology Solutions Company
              205 North Michigan Avenue, Suite 1500
              Chicago, Illinois  60601
              Attention:  Senior Vice President and Chief Financial Officer

              Borrower and Lender may each designate additional or different
addresses by notice to the other party as provided herein.

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              Lender shall be under no obligation to marshal any assets in favor
of Borrower in payment of any or all of Borrower's liabilities hereunder. To the
extent that Borrower makes a payment or payments to Lender, and such payment or
payments or any part thereof are subsequently invalidated, declared to be
fraudulent or preferential, set aside or required to be repaid to a trustee,
receiver or any other party under any bankruptcy law, provincial, state or
federal law, common law or equitable cause, then to the extent of such recovery,
the obligation or part hereof originally intended to be satisfied shall be
revived and continued in full force and effect as if such payment had not been
made or such enforcement or setoff had not occurred.

              Any dispute between Lender and Borrower arising out of, connected
with, related to, or incidental to the relationship established between them in
connection with this Note, and whether arising in contract, tort, equity, or
otherwise, shall be resolved in accordance with the internal laws and not the
conflicts of law provisions of the State of Illinois.

              Except as provided in the immediately succeeding paragraph, Lender
and Borrower each agree that all disputes between them arising out of, connected
with, related to, or incidental to the relationship established between them in
connection with this Note and whether arising in contract, tort, equity, or
otherwise, shall be resolved only by state or federal courts located in Cook
County, Illinois, but Lender and Borrower acknowledge that any appeals from
those courts may have to be heard by a court located outside of Cook County,
Illinois. Borrower waives any and all objections that he may have to the
location of the court considering the dispute.

              Borrower agrees that Lender shall have the right to proceed
against Borrower or his property in a court in any location to enable Lender to
enforce a judgment or other court order entered in favor of Lender. Borrower
agrees that he will not assert any permissive counterclaims in any proceeding
brought by Lender to enforce a judgment or other court order in favor of Lender.
Borrower waives any objection that he may have to the location of the court in
which Lender has commenced a proceeding described in this paragraph.

              Borrower waives personal service of any process upon him and
consents that all such service of process be made by registered mail directed to
Borrower at the address stated herein.

              Borrower waives the posting of any bond otherwise required of
Lender to enforce any judgment or other court order entered in favor of Lender,
or to enforce this note by specific performance, temporary restraining order,
preliminary or permanent injunction.

              Whenever possible, each provision of this Note shall be
interpreted in such manner as to be effective and valid under applicable law,
but if any provision of this Note shall be prohibited by or invalid under
applicable law, such provision shall be ineffective to the extent of such
prohibition or invalidity, without invalidating the remainder of such

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provision or the remaining provisions of this Note. Whenever in this Note
reference is made to Lender or Borrower, such reference shall be deemed to
include, as applicable, a reference to their respective successors and assigns,
and the provisions of this Note shall be binding upon and shall inure to the
benefit of said successors and assigns. Borrower's successors and assigns shall
include, without limitation, a receiver, receiver and manager, trustee or
debtor-in-possession of or for Borrower.

                                            By: /s/ KELLY D. CONWAY
                                               --------------------------------
                                                    Kelly D. Conway
                                                    Borrower

                                      -5-<PAGE>   1
                                                                   Exhibit 4.23

                               December 29, 1999

Vision Twenty-One, Inc.
7360 Bryan Dairy Road, Suite 200
Largo, FL 33777

Attention: Theodore Gillette, Chief Executive Officer

Gentlemen:

         We refer to the Amended and Restated Credit Agreement dated as of July
1, 1998, as amended, between you and us (the "Credit Agreement"). All
capitalized terms used herein without definition shall have the same meaning
herein as such terms are defined in the Credit Agreement.

         The Borrower is in the process of soliciting offers from one or more
investors to sell all or substantial portions of the assets of, or equity
interests in, the Borrower and its Subsidiaries, including without limitation
their managed care business and their refractive surgery business (collectively
being referred to herein as the "V21 Business"). The Borrower expects one or
more letters of intent to acquire the V21 Business being entered into by the
Borrower and such investor(s) with a view to repaying the Obligations owing to
the Banks in full upon consummation of the sale of the V21 Business pursuant to
the terms thereof. Pending the sale of the V21 Business, the Borrower intends
to sell a substantial number of the physician practice management groups
operated by the Borrower and its Subsidiaries (collectively being referred to
herein as the "PPM Businesses"). The Borrower intends to use a portion of the
proceeds from the sale of the PPM Businesses to meet its reasonable and
necessary operating expenses until the sale of the V21 Business is consummated.

         To afford the Borrower an opportunity to consummate the sale of the
V21 Business, the Borrower has requested that the Banks extend the temporary
waiver period provided for in Sections 2.1 and 2.2 of that certain Seventh
Amendment and Waiver to Credit Agreement dated as of December 10, 1999, among
the Borrower, the Banks, and the Agent (the "Seventh Amendment") from December
31, 1999, to February 29, 2000, and postpone the due date for the payment of
principal and interest otherwise due on December 31, 1999, and of interest
otherwise due on January 31, 2000, to February 29, 2000. By signing below, the
Banks hereby agree to extend the waiver period provided in Sections 2.1 and 2.2
of the Seventh Amendment from December 31, 1999, to February 29, 2000, and
agree to postpone the due date for the payment of principal and interest
otherwise due on December 31, 1999, and of interest otherwise due on January
31, 2000, to February 29, 2000, provided that:

                (a) the Borrower agrees that it shall use its best efforts to
         sell the Vision 21 Business or significant parts thereof with a view
         to repaying the Obligations owing to the Banks and to promptly advise
         the Banks of its receipt of any written letters of intent to acquire
         the Vision 21 Business or any significant part thereof (with copies
         thereof to be promptly furnished to the Banks), in each case subject
         to its directors' fiduciary duties;

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Vision Twenty-One, Inc.
December 29, 1999
Page 2

                (b) until the Obligations are paid in full, the Borrower shall
         provide to the Banks a weekly Budget pursuant to Section 1.14(f) of
         the Credit Agreement and such Budget shall be subject to the Approved
         Budget procedures set forth therein, regardless of whether or not then
         being accompanied by a request for a Borrowing of Bridge Loans;

                (c) at all times on and after the date hereof (i) all proceeds
         from the sale of any assets of the Borrower and its Subsidiaries
         (including, without limitation, proceeds from the sale of V21
         Business, the PPM Businesses, or any part thereof), and (ii) cash
         receipts arising from the operation of the business of the Borrower
         and its Subsidiaries not applied pursuant to an Approved Budget, shall
         in each case be remitted promptly upon receipt to the Agent; and

                (d) except to the extent applied to payments pursuant to an
         Approved Budget or applied to the Obligations owing to the Banks,
         proceeds received pursuant to clause (c) above shall be held by the
         Agent as collateral for the remaining Obligations owing to the Banks
         (the Agent hereby being granted a Lien on and right of set-off for the
         benefit of the Banks against all such amounts so held).

The Borrower hereby acknowledges and agrees to the foregoing conditions, and
also hereby acknowledges and agrees that any sale of its or its Subsidiaries'
assets or businesses (whether a sale of the V21 Business or the portions
thereof described herein as the PPM Businesses, or otherwise) shall be subject
to the prior written consent of the Banks, and all proceeds from any such sale
represent proceeds of the Banks' Collateral, to be held by the Agent or applied
to the Obligations pursuant to the terms of the Credit Agreement as modified
hereby.

         Except as specifically modified hereby, all of the terms and
conditions of the Credit Agreement and the other Loan Documents shall stand and
remain unchanged and in full force and effect. This waiver shall become
effective upon the execution and delivery hereof by each of the Banks and the
Borrower as set forth below. This waiver may be executed in counterparts and by
different parties on separate counterpart signature pages, each of which shall
be an original and all of which taken together shall constitute one and the
same instrument. This waiver shall be governed by, and construed in accordance
with, the laws of the State of Illinois.

                          [SIGNATURE PAGES TO FOLLOW]

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Vision Twenty-One, Inc.
December 29, 1999
Page 3

         This waiver letter is entered into by and among the parties hereto as
of the date first above written.

BANK OF MONTREAL, in its individual capacity as BANK ONE TEXAS, N.A. a Bank and
as Agent

By /s/ Jack J. Viang                       By /s/ Ronnie Kaplan
   -----------------------------              -------------------------------
   Name Jack J. Viang                         Name Ronnie Kaplan
   Title Director                             Title Vice President

PACIFICA PARTNERS I, L.P.                  PILGRIM PRIME RATE TRUST

By: Imperial Credit Asset Management,      By: Pilgrim Investments, Inc., as its
    as its Investment Manager                  Investment Manager

By /s/ Dean K. Kawai                       By /s/ Charles E. LeMieux
   -----------------------------              -------------------------------
   Name Dean K. Kawai                         Name Charles E. LeMieux
   Title Vice President                       Title Assistant Vice President

PILGRIM AMERICA HIGH INCOME                MERRILL LYNCH BUSINESS FINANCIAL
INVESTMENTS LTD.                           SERVICES, INC.

By /s/ Charles E. LeMieux                  By /s/ Jeremy M. Dhein
   -----------------------------              -------------------------------
   Name Charles E. LeMieux, CFA               Name Jeremy M. Dhein
   Title Assistant Vice President             Title Assistant Vice President

         Acknowledged and agreed to as of the date first above written.

                                           VISION TWENTY-ONE, INC.

                                           By /s/ Bruce Maller
                                              -------------------------------
                                              Name Bruce Maller
                                              Title Board Chairman

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