Analysis of edge glare phenomena in intraocular lens edge designs.

PURPOSE To determine the image and relative intensity of reflected glare images from 4 commonly used intraocular lens (IOL) edge designs to assess the potential for noticeable postoperative edge glare. SETTING University of Texas Medical School, Houston, Texas, USA. METHODS The interaction of light rays from 4 common IOL edge designs were examined in an eye model using the OptiCAD 3-D radiometric ray-tracing program (Opticad Corp.). Comparison of the potential of the 4 edge designs to produce visual sensations was derived from plots of the spatial location and energy distribution of rays forming the retinal image. RESULTS Edge designs with no anterior and posterior dioptric powers at the lens periphery (lenticular) and rounded corners distributed the edge glare rays over a large retinal area. Edge designs with sharp edges formed by "cropping" the anterior and posterior optic zones focused edge glare rays into distinct arc-shaped images. The peak intensity of the arc-shaped image was 8 to 10 times stronger than the peak intensity of the diffuse image formed by lenses with rounded edges. CONCLUSIONS Rounded IOL edges distribute reflected glare image over a significantly greater area than sharp edges. Rounded edges reduce the potential for edge glare phenomena that appear to the patient as a thin crescent or partial ring.