Dexamethasone and indomethacin attenuate cryopexy. Induced breakdown of the blood-retinal barrier

Pigmented rabbits were pretreated for 3 days with dexamethasone (0.4 mg/kg) or indomethacin (6 mg/kg tid) and then, along with control rabbits, treated with cryopexy administered to the peripheral retina. Drug treatment was continued for the duration of the study. Vitreous fluorophotometry (VFP) was performed prior to cryopexy and on postcryopexy days 3 and 7. Breakdown of the blood-retinal barrier occurred in all three groups but was significantly greater in the control group. Differences were most marked on postcryopexy day 7 when intravitreous fluorescein leakage was decreased to 36% of control in dexamethasone-treated rabbits and 42% of the control group in indomethacin-treated rabbits. Some rabbits, after dexamethasone or indomethacin treatment for 3 days, were given a single posterior cryoapplication just inferior to the optic nerve. On postcryopexy days 1, 3, 7, and 10, VFP was performed by scanning over the treated area. In control rabbits, fluorescein leakage increased over 3 days, while in dexamethasone- and indomethacin-treated rabbits, this increase was significantly blunted. These data demonstrate the beneficial effects of dexamethasone and indomethacin on cryopexy-induced breakdown of the blood-retinal barrier and also suggest a possible mechanism for how such a breakdown occurs.