Time Course of Cold Cataract Development in Anesthetized Mice

Methods: We anesthetized five groups of 10 mice (12 weeks old) with 400 mg/Kg intraperitoneal injections of chloral hydrate and exposed them to 0, 7, 15, 23, and 37 degrees A degrees C for 1 hr. Cataract development was assessed and graded as no cataract, mild, medium, or severe at 10, 20, 30, 45, and 60 min after the exposure started. For quantification purposes, a value from 0 to 3 was assigned to each cataract grade, and the median value was calculated for each group and time point (cataract index, CI). Results: The CI for each temperature fitted a negative exponential equation. We found that four mice of the 37 degrees A degrees C group, nine of the 23 degrees A degrees C group, and all animals of the 15, 7, and 0 degrees A degrees C groups developed cataract. The cataract started at 10 min after exposure to 0 degrees A degrees C and at 20 min when exposed to 7, 15, and 23 degrees A degrees C. The speed of development and CI significantly increased with lower temperatures. Similar results were observed when the procedure was repeated 48 hr later in the 15, 23, and 37 degrees A degrees C groups. In all instances the cataract was reversible. Conclusion: Our findings show that cold cataract development is temperature dependent and that cataract formation starts between 10 and 20 min after exposure to low temperature. This finding is relevant for those experimental settings in which clear ocular media are required.