=============================================================================
                                 UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C.  20549
                                 SCHEDULE 13D
                Under the Securities and Exchange Act of 1934

                               (Amendment No. 8)*

                              Mentor Corporation
               ------------------------------------------------
                               (Name of Issuer)

                    Common Stock, Par Value $0.10 per share
                ------------------------------------------------
                        (Title of Class of Securities)

                                 587188103
                ------------------------------------------------
                               (CUSIP Number)

                           Allison Bennington, Esq.
                              ValueAct Capital
                       435 Pacific Avenue, Fourth Floor
                          San Francisco, CA  94133
                               (415) 362-3700
                ------------------------------------------------
                 (Name, address and telephone number of Person
                 Authorized to Receive Notices and Communications)

                         Christopher G. Karras, Esq.
                                 Dechert LLP
                                  Cira Centre
                                2929 Arch Street
                          Philadelphia, PA 19104-2808
                                (215) 994-4000

                                 June 5, 2006
                ------------------------------------------------
             (Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the
following box [ ].

Note:  Schedules filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 240.13d-7 for other
parties to whom copies are to be sent.

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities,
and for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

This information required on the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("Act") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other provisions of the Act (however, see
the Notes).
=============================================================================


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 587188103                                              Page 2 of 14
-----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   ValueAct Capital Master Fund, L.P.
-----------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS (See Instructions)*                                   WC*

-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                         [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION                British Virgin Islands

-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         2,022,133**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        2,022,133**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

    2,022,133**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

   4.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    PN
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 587188103                                              Page 3 of 14
----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   VA Partners, L.L.C.
-----------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                         [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   Delaware
-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         2,022,133**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        2,022,133**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

    2,022,133**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    4.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    00 (LLC)
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 587188103                                              Page 4 of 14
----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   ValueAct Capital Management, L.P.
-----------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                         [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   Delaware
-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         2,022,133**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        2,022,133**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

    2,022,133**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    4.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    PN
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 587188103                                              Page 5 of 14
----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   ValueAct Capital Management, LLC
-----------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                         [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   Delaware
-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         2,022,133**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        2,022,133**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

    2,022,133**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    4.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    00 (LLC)
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 587188103                                             Page 6 of 14
-----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   Jeffrey W. Ubben
---------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

---------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                         [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   United States
-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         2,022,133**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        2,022,133**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

    2,022,133**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    4.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    IN
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 587188103                                              Page 7 of 14
-----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   George F. Hamel, Jr.
---------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                        [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   United States
-----------------------------------------------------------------------------
                   7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES          8.  SHARED VOTING POWER
   BENEFICIALLY         2,022,133**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH     9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        2,022,133**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

    2,022,133**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    4.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    IN
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 587188103                                             Page 8 of 14
-----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   Peter H. Kamin
-----------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
---------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                        [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   United States
-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         2,022,133**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        2,022,133**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

    2,022,133**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    4.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    IN
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5



THE PURPOSE OF THIS AMENDMENT NO. 8 TO SCHEDULE 13D IS TO AMEND THE
OWNERSHIP REPORTS OF THE REPORTING PERSONS.  THE INFORMATION BELOW
SUPPLEMENTS THE INFORMATION PREVIOUSLY PROVIDED.

Item 1.     Security and Issuer

     This Schedule 13D relates to shares of Common Stock, par value
$0.10 par value per share (the "Common Stock"), of Mentor
Corporation, a Minnesota corporation (the "Issuer").  The address of
the principal executive offices of the Issuer is 201 Mentor Drive,
Santa Barbara, California, 93111.

Item 2.     Identity and Background

      This statement is filed jointly by (a) ValueAct Capital Master Fund,
L.P. ("ValueAct Master Fund"), (b) VA Partners, L.L.C. ("VA Partners"), (c)
ValueAct Capital Management, L.P. ("ValueAct Management L.P. "), (d)
ValueAct Capital Management, LLC ("ValueAct Management LLC"), (e) Jeffrey
W. Ubben, (f) George F. Hamel, Jr. and (g) Peter H. Kamin (collectively,
the "Reporting Persons").

       ValueAct Master Fund is a limited partnership organized under the
laws of the British Virgin Islands. ValueAct Master Fund has a principal
business address of 435 Pacific Avenue, Fourth Floor, San Francisco, CA
94133.

      VA Partners is a Delaware limited liability company, the principal
business of which is to serve as the General Partner to ValueAct Master
Fund. VA Partners has a principal business address of 435 Pacific Avenue,
Fourth Floor, San Francisco, CA 94133.

      ValueAct Management L.P. is a Delaware limited partnership which
renders management services to ValueAct Master Fund.  ValueAct Management
LLC is a Delaware limited liability company, the principal business of
which is to serve as the General Partner to ValueAct Management L.P.  Each
has a principal business address of 435 Pacific Avenue, Fourth Floor, San
Francisco, CA 94133.

     (a), (b) and (c). Messrs. Ubben, Hamel and Kamin are each managing
members, principal owners and controlling persons of VA Partners and
ValueAct Management LLC, and such activities constitute their principal
occupations.  Such individuals are sometimes collectively referred to
herein as the  "Managing Members" or individually as a "Managing Member".
Each Managing Member is a United States citizen and has a principal
business address of 435 Pacific Avenue, Fourth Floor, San Francisco, CA
94133.

     (d) and (e). None of the entities or persons identified in this Item 2
has during the past five years been convicted of any criminal proceeding
(excluding traffic violations or similar misdemeanors), nor been a party to
a civil proceeding of a judicial or administrative body of competent
judgment, decree or final order enjoining future violations of, or
prohibiting or mandating activities subject to, federal or state securities
laws or finding any violation with respect to such laws.

                              Page 9 of 14





ITEM 3.  SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

       Not applicable in that transaction involved the sale of and
not the acquisition of securities.

Item 5.     Interest in Securities of the Issuer

(a) and (b).  Set forth below is the beneficial ownership of shares
of Common Stock of the Issuer for each person named in Item 2.  Shares
reported as beneficially owned by ValueAct Master Fund are also reported as
beneficially owned by (i) VA Partners, as General Partner of each such
investment partnership,(ii) ValueAct Management L.P. as the manager of each
such investment partnership, (iii) ValueAct Management LLC, as General
Partner of ValueAct Management L.P. and (iv) the Managing Members as
controlling persons of VA Partners and ValueAct Management LLC.  VA
Partners, ValueAct Management LLC and the Managing Members also, directly
or indirectly, may own interests in one or more than one of the
partnerships from time to time.  Unless otherwise indicated below, by
reason of such relationships ValueAct Master Fund is reported as having
shared power to vote or to direct the vote, and shared power to dispose or
direct the disposition of, such shares of Common Stock, with VA Partners,
ValueAct Management L.P., ValueAct Management LLC and the Managing Members.

     As of the date hereof, ValueAct Master Fund is the beneficial owner of
2,022,133 shares of Common Stock, representing approximately 4.9% of the
Issuer's outstanding Common Stock.  VA Partners, ValueAct Management L.P.,
ValueAct Management LLC and the Managing Members may each be deemed the
beneficial owner of an aggregate of 2,022,133 shares of Common Stock,
representing approximately 4.9% of the Issuer's outstanding Common Stock.
All percentages set forth in this Schedule 13D are based upon the Issuer's
reported 41,319,261 outstanding shares of Common Stock.

 (c) During the sixty (60) days preceding the date of this report, the
Reporting Persons sold the following shares of Common Stock:


Reporting Person          Trade Date     Shares    Price/Share
----------   	        ---------      -------     -----------
ValueAct Master Fund      06/05/2006     61,200        $42.58
                          06/05/2006     2,000,000*    $42.00

*Shares sold by the Reporting Persons in a private sale to the Issuer.

(d) Not applicable.

(e) As of June 5, 2006 the Reporting Persons ceased to be the
beneficial owners, in the aggregate, of more than five percent of
Issuer Common Stock, and accordingly, their obligation to file a
Schedule 13D has been terminated.



                              Page 10 of 14


Item 6.     Contracts, Arrangements, Understandings or Relationships with
Respect to Securities of the Issuer

       Other than as described elsewhere in this Report and as previously
reported, the Reporting Persons have no understandings, arrangements,
relationships or contracts relating to the Issuer's Common Stock which are
required to be described hereunder.

Item 7.		Material to Be Filed as Exhibits

(1)    Joint Filing Agreement.


                              Page 11 of 14


                                  SIGNATURE
              After reasonable inquiry and to the best of his knowledge and
belief, the undersigned certifies that the information set forth in this
statement is true, complete and correct.

                               POWER OF ATTORNEY
KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears
below on this Schedule 13D hereby constitutes and appoints Jeffrey W. Ubben,
George F. Hamel, Jr. and Peter H. Kamin, and each of them, with full power to
act without the other, his or its true and lawful attorney-in-fact and agent,
with full power of substitution and resubstitution, for him or it and in his
or its name, place and stead, in any and all capacities (until revoked in
writing) to sign any and all amendments to this Schedule 13D, and to file the
same, with all exhibits thereto and other documents in connection therewith,
with the Securities and Exchange Commission, granting unto said attorneys-in
fact and agents, and each of them, full power and authority to do and perform
each and every act and thing requisite and necessary fully to all intents and
purposes as he or it might or could do in person, thereby ratifying and
confirming all that said attorneys-in-fact and agents or any of them, or
their or his substitute or substitutes, may lawfully do or cause to be done
by virtue hereof.

                              ValueAct Capital Master Fund L.P., by
                              VA Partners, L.L.C., its General Partner

                              By:     /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  June 7, 2006            George F. Hamel, Jr., Managing Member

                              VA Partners, L.L.C.

                              By:    /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  June 7, 2006            George F. Hamel, Jr., Managing Member


                               ValueAct Capital Management, L.P., by
                               ValueAct Capital Management, LLC its
                               General Partner

                              By:    /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  June 7, 2006            George F. Hamel, Jr., Managing Member


                               ValueAct Capital Management, LLC

                              By:    /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  June 7, 2006            George F. Hamel, Jr., Managing Member


                              Page 12 of 14





                              By:    /s/  Jeffrey W. Ubben
                                --------------------------------------
Dated:  June 7, 2006            Jeffrey W. Ubben, Managing Member


                              By:    /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  June 7, 2006            George F. Hamel, Jr., Managing Member


                              By:    /s/  Peter H. Kamin
                                --------------------------------------
Dated:  June 7, 2006            Peter H. Kamin, Managing Member


                              Page 13 of 14

  
                                 Exhibit 1
JOINT FILING UNDERTAKING
The undersigned parties hereby agree that the Schedule 13D filed herewith
(and any amendments thereto) relating to the Common Stock of Mentor
Corporation is being filed jointly on behalf of each of them with the
Securities and Exchange Commission pursuant to Section 13(d) of the
Securities Exchange Act of 1934, as amended.


                           ValueAct Capital Master Fund L.P., by
                              VA Partners, L.L.C., its General Partner

                              By:     /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  June 7, 2006            George F. Hamel, Jr., Managing Member

                              VA Partners, L.L.C.

                              By:    /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  June 7, 2006            George F. Hamel, Jr., Managing Member


                               ValueAct Capital Management, L.P.,
                               by, ValueAct Capital Management, LLC
                               its General Partner

                              By:    /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  June 7, 2006            George F. Hamel, Jr., Managing Member


                               ValueAct Capital Management, LLC

                              By:    /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  June 7, 2006            George F. Hamel, Jr., Managing Member


                              By:    /s/  Jeffrey W. Ubben
                                --------------------------------------
Dated:  June 7, 2006            Jeffrey W. Ubben, Managing Member


                              By:    /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  June 7, 2006            George F. Hamel, Jr., Managing Member


                              By:    /s/  Peter H. Kamin
                                --------------------------------------
Dated:  June 7, 2006            Peter H. Kamin, Managing Member

                              Page 14 of 14