Homozygous albino breeding pairs of P23H rats, lines 2 and 3, and S334ter rats, lines 4 and 9, were generously provided by Matthew M. LaVail (University of California, San Francisco, CA). These animals were maintained and bred in barrier cages and fed a fatty-acid–rich diet (Teklad #7904; Harlan-Teklad, Inc., Indianapolis, IN). Heterozygous litters were obtained from crossing homozygous transgenic male offspring with female Sprague-Dawley rats, obtained from Harlan-Teklad, Inc. These animals were fed standard rat chow (#8640; Harlan-Teklad, Inc.). On weaning, heterozygous rats were segregated by sex and moved to a room with dim cyclic light, consisting of 12 hours white light per day (20–30 lux); lights on 8 AM off at 8 PM, or a dark room environment. They, along with weanling male Sprague-Dawley rats, were maintained in their respective rearing environments for 6 weeks. At approximately P60, experimental animals were dark adapted for 16 hours and then treated with intense visible light. After the treatment, the animals were either killed immediately or placed in a dark environment for as long as 14 days before death. All rats were killed in a CO2-saturated chamber. The use of rats in this study conformed to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.