• The primary outcome of this comparative study is the best corrected mesopic log contrast sensitivity function of eyes implanted with Z9000 and MA60 lenses at 6 cycles/degree, 90-120 days postoperatively.
  

• The best corrected mesopic log contrast sensitivity function of eyes implanted with Z9000 and MA60 lenses at 1.5, 3, 12, and 18 cycles/degree, 90-120 days postoperatively
  
• The change in best corrected mesopic log contrast sensitivity function after cataract surgery (postoperatively minus preoperatively) at 1.5, 3, 6, 12, and 18 cycles/degree
  
• The residual spherical aberrations of the postoperative eye using wavefront analysis
  
• Logarithm of the minimum angle of resolution (LogMAR) visual acuity
  
• Postoperative ocular complications/adverse events
  

Today, intraocular lenses (IOLs) are routinely implanted after cataract extraction. Cataract surgical techniques are constantly developing due to innovations in surgical implantation and IOL manufacturing processes. Although material development and surgical implantation have advanced extensively during the past several years, there has been little attention paid to the improvement of the optical quality of IOLs. It has been documented that the vision of an IOL patient is no better than that of a person with healthy eyes of a similar age, i.e., when a 65-year-old patient with cataracts has them removed and implanted with an IOL, the resulting visual outcome is no better than the visual quality of a 65-year-old without cataracts. The fact that the visual quality of the IOL patients is no better than that of their same-age counterparts is surprising because an IOL is optically superior to the natural crystalline lens. This fact may be explained by aberrations. Aberrations cause incoming light that would otherwise be focused to a point to be blurred, which in turn causes a reduction in visual quality. This reduction in quality is more severe under low luminance conditions because ocular aberrations increase when the pupil size gets larger. The Z9000 is an IOL that is designed to counteract the spherical aberration of the cornea and thus improve the resulting visual quality of IOL patients.

Different materials and lens designs result in different visual quality. The handling of the lens, proper centration in the eye, the postoperative course, and the optical image may vary depending on the design of the lens. Two lenses will be compared: AMO Tecnis Z9000 three-piece silicone lens and Alcon Laboratories MA60 three-piece acrylic lens.

This will be a randomized, evaluator-masked study in bilateral cataract surgery patients. Each patient will be assigned to a AMO Tecnis Z9000 lens in one eye and an Alcon Laboratories MA60 lens in the other eye. All first surgeries will be on the right eye. A randomization list will be used to decide lens allocation.

A total of 80 patients (men and women) from the Singapore National Eye Centre will be enrolled in the study. All patients will undergo wavefront analysis 90-120 days postoperatively. The two lens models look different, even in the eye, after implantation. It is not possible to mask the individual investigator at the time of surgery or personnel responsible for conducting the clinical ocular examinations (e.g., evaluation of complications, posterior capsule, IOP, pupil size) and optic evaluations (e.g., evaluation of the IOL).