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                                                                   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