Double image in far peripheral vision of pseudophakic eye as source of negative dysphotopsia.

Abstract

Some intraocular lens (IOL) patients report seeing "dark shadows" at visual angles that are larger than 60°-70°. Raytrace models of the pseudophakic eye show that light starts to miss the IOL at large visual angles because the implant diameter of about 6mm is much smaller than the natural crystalline lens diameter of 9.5mm. This light forms a second displaced image on the peripheral retina. To evaluate the appearance of the image, raytrace software was used to image an illuminated window onto the highly curved retina, and a method was developed to project the image back to object space for evaluation on a flat surface. Only a single schematic eye was evaluated monochromatically and the low resolution of the peripheral retina was not modeled, but the simulated images depict a shadow-like phenomenon at similar visual angles to reports of "negative dysphotopsia."