Retroperfusion Studies of the Aqueous Outflow System. Part I: Evaluation of Technique Using N-ethyl Maleimide

Purpose: The goal of this study was to develop a new technique to deliver drugs or other agents to the lumen of the angular aqueous plexus/Schlemm's canal (AAP/SC) while bypassing the trabecular meshwork, thereby gaining insight into AAP/SC inner wall function.

Methods: The anterior chamber is held at a small negative pressure and fluid is allowed to flow retrograde from the limbal vessels, through the collector channels, and into the AAP/SC ("retroperfusion"). Facility measurements are combined with histologic and tracer studies in bovine eyes.

Results: (1) Retroperfusion with a saline solution does not alter facility or change outflow pathway morphology; (2) fluid is able to move retrograde from the scleral surface and enter the lumen of the AAP; and (3) retroperfusion with N-ethyl maleimide causes a dose-dependent increase in washout rate and concomitant inner wall breaks.

Conclusions: It is hypothesized that the observed increase in washout is due to leakage of extracellular materials through breaks in the inner wall.