Wavefront technology in cataract surgery

Abstract

As advances in technology allow cataract surgeons to address higher order optical aberrations, the measurement of functional vision becomes increasingly critical. Contrast sensitivity testing is assuming a prominent place in our evaluation of surgical modalities because it reflects functional vision and correlates with visual performance. The Tecnis Z9000 intraocular lens (IOL) (Pfizer, New York) is the first foldable IOL designed to correct higher order optical aberrations and represents a first step toward the integration of wavefront technology and cataract surgery. Contrast sensitivity declines with age, even in the absence of ocular pathology. Wavefront science demonstrates that the youthful crystalline lens compensates for aberrations in the cornea. The aging lens loses its balance with the cornea, as both the magnitude and the sign of its spherical aberration change. Older pseudophakic patients have generally the same contrast sensitivity as their age-matched counterparts without cataract. The Tecnis Z9000 IOL (Pfizer, New York) has been designed with a modified prolate anterior surface to compensate for the spherical aberration of the cornea, thus eliminating total ocular spherical aberration. Clinical data demonstrate that this modified prolate IOL provides superior functional vision, similar to that of younger people, and hence improves visual performance when compared with conventional spherical IOLs. It appears likely that the decline in functional vision with age involves changes in the spherical aberration of the crystalline lens. The integration of wave-front technology and lens-based surgery represents a step toward improving functional vision and quality of life for cataract patients.