Effects of transcorneal freezing on protein content of aqueous humor and intraocular temperature in rabbit and cat.

The effects of transcorneal freezing on protein content of aqueous humor and intraocular temperature at the posterior surface of the cornea, the angle, the iris, and the ciliary processes were determined in rabbits and cats. Normal aqueous protein concentration was 40 +/- 2 mg/dl in rabbits and 43 +/- 4 mg/dl in cats. In rabbits, total aqueous protein content reached its highest level (2790 +/- 302 mg/dl) for 3 hr after transcorneal freezing, decreased by 50% after 4 hr, and was not significantly different than normal at 7 days. In cats, total aqueous protein content also reached its highest level (1610 +/- 290 mg/dl) 3 hr after corneal freezing. Fluctuations occurred thereafter, but protein content was not significantly different from normal after 7 days. The temperature at the corneal endothelium always decreased to below 0 degrees C with a 10 to 25 sec application of the cryoprobe to the cornea in rabbit and cat. Intraocular temperature did not decrease below 24 degrees C at the angle or ciliary processes during application of the cryoprobe for up to 25 sec, whereas the temperature at the pupillary margin of the iris sometimes decreased to near 0 degrees C with a 15 to 25 sec application.