Recent developments in aspheric intraocular lenses

Abstract

Aspheric intraocular lenses (IOLs) were designed to improve functional vision on the assumption that reducing ocular spherical aberration would lead to improvements in contrast sensitivity. Although this has largely been confirmed by many studies, several recent studies have reported no difference in contrast sensitivity or in patient preference. The purpose of this article is to review recent findings and offer explanations for these apparently contradictory results. Studies report excellent and reliable visual acuity with aspheric IOLs. Compared with spherical IOLs, spherical aberration is either lower, or entirely eliminated, depending on the IOL implanted, and most earlier studies report a corresponding improvement in contrast sensitivity and various aspects of functional vision. Articles appearing in the past 12-18 months vary, with some reporting marked improvements in contrast sensitivity and patient preference, and others finding no difference either in functional vision or subjective evaluation. Possible reasons include suboptimal targeting of residual spherical aberration, insufficient follow-up for differences to become apparent and physiological limitations on perceived visual quality. Aspheric IOLs offer improved functional vision to patients but may need to be better targeted. As a growing number of younger patients undergo clear lens extraction, differences in visual quality may become better appreciated.