A Novel Schlemm's Canal Scaffold Increases Outflow Facility in a Human Anterior Segment Perfusion Model

Abstract

An intracanalicular scaffold (Hydrus microstent) designed to reduce intraocular pressure as a glaucoma treatment was tested in human anterior segments to determine changes in outflow facility (C). Human eyes with no history of ocular disease or surgeries were perfused within 49 hours of death. The anterior segments were isolated and connected to a perfusion system. Flow rates were measured at pressures of 10, 20, 30, and 40 mm Hg. The scaffold was inserted into Schlemm's canal of the experimental eye, while a control eye underwent a sham procedure. Flow rate measurements were repeated at the four pressure levels. Individual C values were computed by dividing the flow rate by its corresponding pressure, and by averaging the four individual C measurements. The change in C between control and experimental eyes was assessed by the ratio of the baseline and second C measurement. In two eyes, the placement of the scaffold was evaluated histologically. After scaffold implantation in the experimental eyes, the average C increased significantly from baseline (n = 9, P < 0.05). Ratios of C at all pressure levels, except for 10 mm Hg, were significantly higher in experimental eyes (n = 9) than control eyes (P < 0.05, n = 7). Histologically, the scaffold dilated Schlemm's canal with no visible damage to the trabecular meshwork. The Hydrus Microstent provided an effective way to increase outflow facility in human eyes ex vivo.