EXHIBIT 32.1

CERTIFICATION PURSUANT TO SECTION 906
OF THE SARBANES-OXLEY ACT OF 2002

CERTIFICATION OF CHIEF EXECUTIVE OFFICER AND CHIEF FINANCIAL OFFICER
PURSUANT TO
18 UNITED STATESC. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

I, Elizabeth H. Dávila, certify, pursuant to 18 UNITED STATESC. Section 1350, as adopted pursuant to Section 906 of Sarbanes-Oxley Act of 2002, that the Annual Report of VISX, Incorporated on Form 10-K for the period ended December 31, 2004 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Annual Report on Form 10-K fairly presents, in all material respects, the financial condition and results of operations of VISX, Incorporated.

/s/Elizabeth H. Dávila  

Elizabeth H. Davila 

Chief Executive Officer 
March 9, 2005

I, Derek A. Bertocci, certify, pursuant to 18 UNITED STATESC. Section 1350, as adopted pursuant to Section 906 of Sarbanes-Oxley Act of 2002, that the Annual Report of VISX, Incorporated on Form 10-K for the period ended December 31, 2004 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Annual Report on Form 10-K fairly presents, in all material respects, the financial condition and results of operations of VISX, Incorporated.

/s/Derek A. Bertocci  

Derek A. Bertocci 

Chief Financial Officer 
March 9, 2005