OPTICAL ZONE DIAMETERS FOR PHOTOREFRACTIVE CORNEAL SURGERY

Purpose. To examine the physiological optics of photorefractive cornea l surgery and to study the effect on glare production of the optical z one diameter. Methods. An optical analysis computer program was used t o generate rays that define the edge of the optical zone for any given pupil size and glare-free field. Results. The optical zone diameter m ust be based on the postoperative corneal curvature because that deter mines magnification of the pupil. The minimal optical zone diameter of uniform optical power was determined both for myopic and hyperopic su rgery and for two values of anterior chamber depth. Conclusions. Optic al zone diameters must be at least as large as the entrance pupil diam eter to preclude glare at the fovea, and larger than the entrance pupi l to preclude parafoveal glare.