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                                                                   EXHIBIT 10.10

                               FOURTH AMENDMENT TO

                                 ALLERGAN, INC.

                                  PENSION PLAN
                                 (RESTATED 1996)

       The ALLERGAN, INC. PENSION PLAN (the "Plan") is hereby amended, effective
January 1, 2000, to read as follows:

1.     Section 9.3(b) of the Plan is hereby amended and restated in its entirety
       to read as follows:

              "(b) In the event of a Change in Control (as herein defined), all
       Participants who were Participants on the date of such Change in Control
       shall become 100% vested in their Accrued Benefits on the date of such
       Change in Control and in any benefit accruals subsequent to the date of
       the Change in Control. Notwithstanding the foregoing, the Board of
       Directors may, at its discretion, amend or delete this Paragraph (b) in
       its entirety prior to the occurrence of any such Change in Control. For
       the purpose of this Paragraph (b), "Change in Control" shall mean the
       following and shall be deemed to occur if any of the following events
       occur:

                     (i) Any "person," as such term is used in Sections 13(d)
              and 14(d) of the Securities Exchange Act of 1934, as amended (the
              "Exchange Act") (a "Person"), is or becomes the "beneficial
              owner," as defined in Rule 13d-3 under the Exchange Act (a
              "Beneficial Owner"), directly or indirectly, of securities of
              Allergan representing (i) 20% or more of the combined voting power
              of Allergan's then outstanding voting securities, which
              acquisition is not approved in advance of the acquisition or
              within 30 days after the acquisition by a majority of the
              Incumbent Board (as hereinafter defined) or (ii) 33% or more of
              the combined voting power of Allergan's then outstanding voting
              securities, without regard to whether such acquisition is approved
              by the Incumbent Board;

                     (ii) Individuals who, as of the date hereof, constitute the
              Board of Directors (the "Incumbent Board"), cease for any reason
              to constitute at least a majority of the Board of Directors,
              provided that any person becoming a director subsequent to the
              date hereof whose election, or nomination for election by
              Allergan's stockholders, is approved by a vote of at least a
              majority of the directors then comprising the Incumbent Board
              (other than an

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              election or nomination of an individual whose initial assumption
              of office is in connection with an actual or threatened election
              contest relating to the election of the directors of Allergan, as
              such terms are used in Rule 14a-11 of Regulation 14A promulgated
              under the Exchange Act) shall, for the purposes of this Plan, be
              considered as though such person were a member of the Incumbent
              Board of Allergan;

                     (iii) The consummation of a merger, consolidation or
              reorganization involving Allergan, other than one which satisfies
              both of the following conditions:

                            (A) a merger, consolidation or reorganization which
                     would result in the voting securities of Allergan
                     outstanding immediately prior thereto continuing to
                     represent (either by remaining outstanding or by being
                     converted into voting securities of another entity) at
                     least 55% of the combined voting power of the voting
                     securities of Allergan or such other entity resulting from
                     the merger, consolidation or reorganization (the "Surviving
                     Corporation") outstanding immediately after such merger,
                     consolidation or reorganization and being held in
                     substantially the same proportion as the ownership in
                     Allergan's voting securities immediately before such
                     merger, consolidation or reorganization, and

                            (B) a merger, consolidation or reorganization in
                     which no Person is or becomes the Beneficial Owner,
                     directly or indirectly, of securities of Allergan
                     representing 20% or more of the combined voting power of
                     Allergan's then outstanding voting securities; or

                     (iv) The stockholders of Allergan approve a plan of
              complete liquidation of Allergan or an agreement for the sale or
              other disposition by Allergan of all or substantially all of
              Allergan's assets.

Notwithstanding the preceding provisions of this Paragraph (b), a Change in
Control shall not be deemed to have occurred if the Person described in the
preceding provisions of this Paragraph (b) is (1) an underwriter or underwriting
syndicate that has acquired any of Allergan's then outstanding voting securities
solely in connection with a public offering of Allergan's securities, (2)
Allergan or any subsidiary of Allergan or (3) an employee stock ownership plan
or other employee benefit plan maintained by the Company that is qualified under
the provisions of the Internal Revenue Code of 1986, as amended. In addition,
notwithstanding the preceding provisions of this Paragraph (b), a Change in
Control shall not be deemed to have occurred if the Person described in the
preceding

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provisions of this Paragraph (b) becomes a Beneficial Owner of more than the
permitted amount of outstanding securities as a result of the acquisition of
voting securities by Allergan which, by reducing the number of voting securities
outstanding, increases the proportional number of shares beneficially owned by
such Person, provided, that if a Change in Control would occur but for the
operation of this sentence and such Person becomes the Beneficial Owner of any
additional voting securities (other than through the exercise of options granted
under any stock option plan of Allergan or through a stock dividend or stock
split), then a Change in Control shall occur."

       IN WITNESS WHEREOF, Allergan, Inc. hereby executes this Fourth Amendment
on the 30th day of December, 1999.

ALLERGAN, INC.


BY: /s/ Francis R. Tunney, Jr.
    --------------------------------
    Francis R. Tunney, Jr.,
    Corporate Vice President--Administration,
    General Counsel and Secretary