Effects of intracameral hydrogen peroxide in the rabbit anterior chamber.

The effects of intracameral injection of hydrogen peroxide were examined using different techniques in young (4 to 6 weeks of age, approximately equal to 500 g) and adult (3 to 6 months of age, 2.5 to 3.5 kg) rabbits. A response occurred that included changes in intraocular pressure, increased permeability of the iris vasculature, and swelling of the ciliary processes. The initial fall in intraocular pressure was the same in young and adult rabbits and the time to recovery of normal intraocular pressure was statistically the same in young rabbits as in adults. The loss of iris vascular integrity was more pronounced in adult animals, as judged by the appearance of fluorescein in the iris and anterior chamber. Microscopy revealed that the ciliary processes of young rabbits were unaffected by hydrogen peroxide, whereas in adult animals considerable swelling of the ciliary processes occurred. No polymorphonuclear leucocytes were observed in micrographs, ruling out their involvement in the response. The rate of loss of injected hydrogen peroxide from the anterior chamber was significantly longer in adult relative to young animals. Young animals had statistically higher catalase activity (U/mg wet weight) in iris and corneal endothelium than older animals. Differences exist in both the anterior segment response to, and the rate of clearance of, intracameral hydrogen peroxide injection in rabbits of at least two different ages that may reflect the differences found in tissue catalase concentrations.