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Direct visualization of negative dysphotopsia in a physical model of the pseudophakic eye


Purpose : Negative dysphotopsia (ND) is a photic phenomenon affecting pseudophakic eyes where a dark crescent or shadow is perceived in the peripheral temporal visual field. Although is it understood that the edge of the intraocular lens (IOL) and the space between the IOL’s optic and the posterior iris are involved, the exact etiology remains unclear especially with respect to its clinical manifestation. The purpose of the study was to develop a physical model of the pseudophakic eye and to record ND at the retinal plane in a variety of conditions.

Methods : The eye model had realistic dimensions with a cornea made of PMMA (R=7.73mm, Q= -0.24) an iris at a depth of 3.55mm and an IOL holder with variable distance (0.5 to 1.5mm) from the pupil, simulating a pseudophakic anterior chamber depth (pACD) ranging from 4.05 to 5.05 mm. The eye was filled with distilled water. A board level camera (DFM 72BUC02-ML, Imaging Source, Germany) in a water-tight container with a 200μm glass window was used to record the retinal images. Negative dysphotopsia was investigated for two different types of IOLs (Acrysof SA60AT, Alcon, TX USA and ArtIOL, Art55, Voptica SL, Murcia, Spain), for two different pACD values (4.05 and 5.05 mm) and for two different pupil diameters (3 and 6 mm).

Results : A characteristic crescent appeared on the retina when a point source was positioned at an angle of 75 degrees with respect to the optical axis of the eye. The phenomenon was prominent for a pupil diameter of 6 mm and pACD of 5.05 mm. For 3 mm pupil diameter and for shallower pACD (4.05 mm) the phenomenon was not observed. When imaging an extended uniform field, a dark band having a width of approximately 4 degrees and brightness reduced at 74% of the field brightness appeared at the vicinity of 75 degrees. The crescent was less prominent for the meniscus lens (ArtIOL), presumably due to the smaller gap between the IOL edge and the posterior iris.

Conclusions : A peripheral crescent, corresponding to light that misses the IOL’s optic results to the formation of a darker zone, between the light that is focused by the IOL and light that is missing the IOL. ND appeared only for large pupils and deep chambers and was reduced for inverted meniscus IOLs. However in clinical practice where IOL tilt and decentration can occur, ND could be manifested for smaller pupil diameters and pACD.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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