THEORETICAL AND PRACTICAL PERFORMANCE OF A CONCENTRIC BIFOCAL INTRAOCULAR IMPLANT LENS

Some results from a survey of 43 patients who had a monofocal intra-oc ular-lens (TOL) in one eye and a concentric bifocal intra-ocular-lens in the fellow eye are reported. Twenty patients with 6/9 or better pos t-operative visual acuity in both eyes, participated in the main part of the study. Optical transfer functions for the bifocal lens showed t hat, compared to an optimal single-vision correction, there is a 50% c ontrast degradation of the distance retinal image across all spatial f requencies above around 3 c/deg. For the patients in the main study, t here was a close correspondence between practical measurement of contr ast sensitivity and the theoretical predictions of the modulation tran sfer functions. Measuring contrast sensitivity proved an effective mea ns of assessing misalignment of the bifocal IOLs. (C) 1998 Elsevier Sc ience Ltd. All rights reserved.