Cataract is prevalent throughout the world and IOLs are routinely implanted after the extraction of the cataractous lens. It is the most frequently performed surgery in the United States with an estimated 2-3 million procedures performed annually. With the aging population on the rise, as well as the increasing popularity of refractive intraocular lenses, the number of intraocular surgeries continues to rise. Over the years, the surgical technique has evolved from intracapsular extraction to modern phacoemulsification. This development has helped with the evolution of IOLs as well. The IOLs have advanced extensively: different materials and designs are available, permitting implantation through smaller, sutureless incisions. Traditional IOLs are of monofocal design providing vision at one distance, typically far. Patients implanted with traditional monofocal IOLs usually require glasses for near distance tasks such as reading. The new multifocal IOLs offer the possibility of seeing well at more than one distance, without glasses or contacts.

The AcrySof ReSTOR (Alcon Laboratories) uses apodized diffractive technology — a design that responds to how wide or small the eye's pupil might be — to provide near, intermediate, and distance vision. Clinical studies used to support the March 2005 FDA approval showed that 80% of people who received the lens did not use glasses for any activities after their cataract surgery; 84% who received the lens in both eyes had distance vision of 20/25 or better, with near vision of 20/32 or better.

ReZoom (Advanced Medical Optics) is a multifocal refractive zonal IOL that distributes light over five optical zones to provide near, intermediate, and distance vision. The ReZoom is a second-generation multifocal and was FDA-approved in March 2005. In a European study of 215 patients, 93% of ReZoom recipients reported never or only occasionally needing glasses. The combined use of multifocal intraocular lenses is often a solution to best meet the patients' refractive needs. There has been speculation that the implantation of ReSTOR in one eye and ReZoom lens in the fellow eye can provide patients a larger range of useful vision in the near range.

The purpose of this study is to evaluate visual outcome and patient satisfaction after implantation of a diffractive multifocal IOL (ReSTOR) in one eye and a refractive multifocal IOL (ReZoom) in the fellow eye after routine phacoemulsification and compare it to a control group of patients implanted bilaterally with ReSTOR with both eyes targeted for 0 to ±0.25 D, and to a group of patients implanted bilaterally with ReSTOR with the non-dominant eye targeted for +1.00 D and the dominant eye targeted for 0 to +0.25 D.