Abstract
Abstract: :
Purpose: To objectively evaluate and compare optical and visual performances of three intraocular lenses (IOLs) using an opto–mechanical eye model. Methods:Three monofocal IOLs of the same power (+23D) were tested: Tecnis Z9000 (silicone, prolate surface, square edge, equiconvex); Acrysof MA60BM (PMMA, a 6 mm optic, equiconvex), Acrysof Natural SN60AT (PMMA, a 6 mm optic biconvex). The IOLs were placed in an experimental eye model filled with water reproducing the optical and mechanical properties of the Gullstrand theoretical model, featuring a PMMA prolate cornea, a variable iris, and a CCD retina reproducing the spatial resolution of the human fovea. The pseudophakic eye model was optically evaluated through aberrometry (LADARWave, Alcon), and its visual acuity (VA) was quantified by projecting optotype charts of variable contrast on it and having a masked reader to interpret the CCD output signal displayed on a monitor. Results: Aberrometry revealed a positive value of Spherical Aberration for both Acrysof IOLs, and a negative one for the Z9000 (consistently with its optical design). VA at 3 mm pupil size was better for the Z9000 at all contrast values (2 to 100%) by an amount of 0.5 to 2 VA lines (peak VA=0.14 logMAR). VA measured at 5 mm pupil was lower than at 3 mm, and resulted within 1 VA line difference for Z9000 and MA60BM, being definitely lower for SN60AT. Conclusions:This study confirms the effectiveness of the Z9000 optical design in reducing the overall spherical aberration of the eye, providing better VA at all contrast values and pupil sizes. The inclusion of photopigment for retinal protection (Acrysof SN60AT) slightly worsens the visual performance. The optomechanical eye model proved to be a valid bench test for optical and visual evaluation of IOLs
Keywords: cataract • crystallins • quality of life