Sodium iodate (Sigma-Aldrich Corp., St. Louis, MO) was dissolved in sterile normal saline as a 4% stock solution (wt/vol). The rats were anesthetized by intraperitoneal injection of ketamine (35 mg/kg, Ketaset; Fort Dodge Animal Health, Fort Dodge, IA) and xylazine (5 mg/kg, TranquiVed; Vedco, Inc., St. Joseph, MO). A single intravenous or intraperitoneal injection of sodium iodate was given. For intravenous injection, the rats were divided into four groups; each received a single injection of 25, 40, 50, or 75 mg/kg sodium iodate. The control animals were injected with the same volume of normal saline or 75 mg/kg sodium iodide; the latter was administered at an ionic strength comparable to that of the highest dose of sodium iodate used in this study. For intraperitoneal injection, only two doses were tested (50 and 75 mg/kg) in order to compare the effect on retina with that in rats injected intravenously. After the injection, the rats were returned to the colony and kept under standard conditions.