Aqueous humor dynamics in experimental iridocyclitis

Abstract

Ocular inflammation was induced by intravitreal bovine serum albumin (BSA) injection in one eye of each of six cynomolgus monkeys. The fellow eyes were injected with sterile saline alone. The intraocular pressure decreased by 12.2 +/- 1.3 mmHg (mean +/- SE) 2 days after BSA injection and 4.0 +/- 1.1 mmHg after saline injection. Aqueous flow and uveoscleral outflow were determined with fluorescein isothiocyanate (FITC) dextran 70. Aqueous flow in inflamed eyes averaged 0.32 +/- 0.04 ul/min, less than half the rate of control eyes (0.77 +/- 0.08 ul/min, P = 0.01). The facility of uveoscleral outflow in inflamed eyes was four times that of control eyes (0.2 +/- 0.03 vs 0.05 +/- 0.01 ul/min/mmHg, respectively, P = 0.009). Fluorescence microscopic examination revealed intense fluorescence of the edematous ciliary body muscle and of the suprachoroidal space extending to the posterior pole. These findings indicate that BSA-induced ocular inflammation causes a simultaneous reduction in aqueous humor flow and an increase in uveoscleral outflow, resulting in ocular hypotony.