Serum effects on aqueous outflow during anterior chamber perfusion in monkeys

Purpose. To prevent the increase in outflow facility during anterior chamber perfusion in nonhuman primates by the addition of autologous serum to Barany's mock aqueous humor. Methods. Total outflow facility was measured simultaneously in both eyes of living cynomolgus monkeys for 3 hours by two- level constant pressure perfusion of the anterior chambers from elevated reservoirs with Barany's solution with (one eye) or without (opposite eye) 3%, 5%, 10%, or 15% to 20% autologous serum. In other experiments, the anterior chamber contents initially were exchanged with Barany's solution with (one eye) or without (opposite eye) 5% autologous serum, and the facility response to intravenous pilocarpine was determined. Results. Eyes perfused with serum had a lower starting facility than control eyes, with facility decreasing with increasing serum concentrations. For both groups, facility increased with perfusion time and with volume of fluid perfused through the eye, but the rate of change of facility over time and per change in volume was significantly less for the serum-treated eyes. This difference remained significant when the proportional change of facility relative to baseline level was analyzed as a function of time but not as a function of volume. Intravenous infusion of pilocarpine increased facility by approximately the same proportion relative to baseline in both groups, but the absolute change and the final facility were lower in the serum-treated eyes. Conclusions. Serum or a serum component in the vicinity of the trabecular meshwork normally may help maintain outflow resistance but may be washed away during perfusion with serum-free media.