ε-Aminocaproic acid does not inhibit outflow resistance washout in monkeys

Purpose. To determine whether the anti-fibrinolytic agent ε-aminocaproic acid (EACA) inhibits the washout of resistance to aqueous humor outflow during anterior chamber perfusion in cynomolgus monkeys, as it does in rabbits. Methods. Nine adult ocular normotensive cynomolgus monkeys underwent bilateral anterior chamber perfusion with Barany's solution, containing 3.8 mM EACA unilaterally. Total outflow facility was determined in both eyes simultaneously for approximately 4 hours by the two-level constant pressure method. The data were analyzed using a linear regression model that tested treated versus control eye differences over time against a slope and intercept of 0.0. Results. Outflow facility increased and resistance decreased significantly over time similarly in both EACA-treated and control eyes; i.e., neither the slopes nor the intercepts for facility or resistance, respectively, differed between the eyes over the entire 4-hour measurement period or for the initial 90 minutes considered separately. The facility increase and resistance decrease as functions of perfusion volume also were similar in EACA-treated and control eyes. Conclusions. EACA at this dose does not prevent resistance washout in the cynomolgus monkey, in contrast to the rabbit. This species difference may relate to the vastly different anatomy and physiology of their outflow pathways.