Effect of illumination on visual function after monofocal and multifocal intraocular lens implantation

Abstract

To compare best-corrected visual acuity (BCVA) and contrast sensitivity (CS) under different levels of illumination in patients who had monofocal and multifocal intraocular lenses (IOLs) and to establish the effect of different lighting conditions on vision in the two groups of patients. We retrospectively reviewed 27 patients who underwent phacoemulsification for age-related cataract and IOL implantation of either monofocal (SI30NB; n=10, 37%) or multifocal (SA40N; n=17, 63%) IOLs. Binocular distance and near BCVA and CS were tested using logMAR and Pelli-Robson charts that were externally illuminated with 20, 200, 400, and 1600 lux, and were compared using repeated-measures analysis of variance. A questionnaire was administered to establish the lighting preference in the two groups and the effect of lighting conditions on their vision. Binocular distance and near BCVA and CS significantly increased with increasing illumination from 20 to 200 lux in the monofocal (mean=0.04 vs -0.07; P=0.006; 0.37 vs 0.26, P=0.002 and 1.47 vs 1.60, P=0.01) as well as in the multifocal group (mean=0.03 vs -0.12, P<0.001; 0.38 vs 0.23, P<0.001 and 1.47 vs 1.61, P=0.002). No significant difference in BCVA or CS was found between the two groups at any of the four illumination levels. Both groups had similar lighting preference, but 43.8% of patients in the multifocal group experienced subjective worsening of their vision in bright outdoor lights. Distance and near BCVA and CS improve with increasing illumination in patients with monofocal and multifocal IOLs, but remain comparable in the two groups under common levels of indoor illumination. Patients with multifocal IOLs may experience worsening of their vision in bright outdoor lights.