Vignetting and peripheral double images with intraocular lenses.

Abstract

Intraocular lenses (IOLs) are widely used, yet raytrace evaluations show that vignetting at very large angles limits the visual field of the focused image, though this is not specifically noticed by patients. A rare patient observation of peripheral double images in both eyes was modeled to demonstrate that a second image can be formed more peripherally by light missing the IOL, with simulated images illustrating the effect. Bothersome "dark shadows" that are reported by a small percentage of IOL patients, called negative dysphotopsia, have a similar cause, but are never reported as double images. The eyes had average dimensions, but the iris was thinner on the temporal side, with a nasally decentered pupil, and a distinct gap between the iris and the IOL, which all permit additional light to miss the IOL to create the second image.