Exhibit 4.1

                                 THIRD AMENDMENT
                                     to the
                                RIGHTS AGREEMENT
                                     between
                               VISX, INCORPORATED
                                       and
                          EQUISERVE TRUST COMPANY, N.A.

      This Third Amendment (the "Amendment") to the Rights Agreement dated as of
August 3, 2000 and amended on April 25, 2001 and May 15, 2003 (the "Rights
Agreement"), is made and entered into as of November 9, 2004 between VISX,
INCORPORATED, a Delaware corporation (the "Company"), and EQUISERVE TRUST
COMPANY, N.A. (the "Rights Agent").

      WHEREAS, the Company and the Rights Agent entered into the Rights
Agreement specifying the terms of the Rights (as defined therein);

      WHEREAS, pursuant to Section 26 of the Rights Agreement, the Company
desires to amend the Rights Agreement as set forth below; and

      WHEREAS, on November 9, 2004, the Board of Directors of the Company has
approved and adopted this Amendment at a meeting of directors duly called and
held.

      NOW, THEREFORE, for good and valuable consideration, the receipt and
adequacy of which are hereby acknowledged, the parties hereto agree as follows:

      1. Capitalized Terms. All capitalized, undefined terms used in this
Amendment shall have the meanings assigned thereto in the Rights Agreement.

      2. Supplement to Definitions. The definitions contained in Section 1 of
the Rights Agreement shall be supplemented by adding the following:

            "`Merger Agreement' shall mean the Agreement and Plan of Merger by
and among Advanced Medical Optics, Inc., Vault Merger Corporation and VISX,
Incorporated dated as of November 9, 2004."

      3. Addition of New Section 34. The Rights Agreement is hereby amended by
adding a new Section 34 thereof which shall read as follows:

            "Notwithstanding anything in this Agreement to the contrary, neither
a Distribution Date nor a Stock Acquisition Date shall be deemed to have
occurred, and neither Parent nor Merger Sub (each as defined in the Merger
Agreement) shall be deemed to have become an Acquiring Person, and no holder of
any Rights shall be entitled to exercise such Rights under, or be entitled to
any rights pursuant to this Agreement, in any such case solely by virtue of (a)
the approval, execution or delivery of the Merger Agreement (or any amendment
thereto approved in advance by the Board of Directors of the Company), or (b)
the consummation of the transactions contemplated by the Merger Agreement."



      4. Amendment of Section 7(a). Section 7(a) of the Rights Agreement is
amended by deleting the word "or" immediately preceding clause (ii) thereof and
adding the following new phrase immediately following clause (ii) thereof: "or
(iii) immediately prior to the Effective Time of the Merger (each as defined in
the Merger Agreement)," and also by deleting the parenthetical on the last line
of Section 7(a) and replacing it with the following parenthetical: "(the earlier
of (i), (ii) and (iii) being herein referred to as the "Expiration Date")."

      5. Effectiveness. This Amendment shall be deemed effective as of November
9, 2004, as if executed by both parties hereto on such date, and except as
expressly provided herein, the Rights Agreement shall be and remain in full
force and effect.

      6. Governing Law. This Amendment shall be governed by and construed in
accordance with the laws of the State of Delaware applicable to contracts made
and to be performed entirely within such state.

      7. Counterparts. This Amendment may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which taken
together constitute one and the same instrument.

      8. Severability. If any term, provision, covenant or restriction of this
Amendment is held by a court of competent jurisdiction or other authority to be
invalid, void or unenforceable, the remainder of the terms, provisions,
covenants and restrictions of this Amendment shall remain in full force and
shall in no way be affected, impaired or invalidated.


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         IN WITNESS WHEREOF, the Company and the Rights Agent have caused this
Amendment to be duly executed as of the date first above written.

Attest:                                    VISX, INCORPORATED


By:     /S/ SCOTT MEGGS                    By:     /S/ JOHN F. RUNKEL, JR.
      --------------------------------           -------------------------------
Name:   Scott Meggs                        Name:   John F. Runkel, Jr.
      --------------------------------           -------------------------------
Title:  Corporate Counsel                  Title:  General Counsel
      --------------------------------           -------------------------------


Attest:                                    FLEET NATIONAL BANK
                                           as Rights Agent

By:     /S/ DEBRA SPEARIN                  By:     /S/ MICHAEL J. CONNOR
      --------------------------------           -------------------------------
Name:   Debra Spearin                      Name:   Michael J. Connor
      --------------------------------           -------------------------------
Title:  Account Manager                    Title:  Managing Director
      --------------------------------           -------------------------------


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