Intraindividual Comparison of Functional Vision and Higher Order Aberrations After Implantation of Aspheric and Spherical Intraocular Lenses

Abstract

To compare the intraindividual effects of an aspheric intraocular lens (IOL) (Tecnis Z9000, Advanced Medical Optics Inc [AMO]) with a conventional spherical IOL (AcrySof single-piece SA60AT, Alcon Laboratories Inc) on functional vision and higher order aberration. In this prospective study, 40 eyes of 20 patients presenting for cataract surgery were randomly assigned to receive a spherical IOL (AcrySof one-piece) in one eye and an aspheric IOL (Tecnis) in the contralateral eye. Patients were followed for 3 months postoperatively. The results of sine-wave grating contrast sensitivity, contrast acuity under mesopic and photopic conditions, and higher order aberrations (3rd, 4th, and 5th order, primary spherical and total) root-mean-square (RMS) were compared intraindividually. The postoperative corneal higher order aberrations were not significantly different between the two IOL groups. Total higher order aberrations, total 4th order, and primary spherical aberrations were significantly lower in the Tecnis group at pupil size > 5 mm. Contrast acuity was not significantly different between the two IOL groups under mesopic and photopic conditions. Mean pupil size under mesopic conditions was 4.20 mm and 4.08 mm in the AcrySof and Tecnis groups, respectively. Sine-wave contrast sensitivity test results were slightly better in the Tecnis group at spatial frequencies of 1.5, 3, 6, and 12 cycles per degree, but these differences did not reach statistical significance. Compared to conventional spherical IOL, the Tecnis aspheric IOL significantly reduced total ocular and spherical aberration but did not result in better functional vision under mesopic or photopic conditions. Small pupil size may be a factor, which limits the beneficial effect of aspheric IOLs on visual performance.