In vitro flow testing of glaucoma drainage devices.

Abstract

The study was intended to determine methods that could evaluate in vitro the flow characteristics of glaucoma drainage devices. Two test methods were used: (1) a gravity-driven flow test and (2) a syringe-pump-driven flow test. Eighteen devices, both valved and nonvalved, from 4 manufacturers were evaluated for their hydrodynamic resistance and the pressure at which the flow becomes 0. Results show a wide variation in device performance, indicating a strong need for enhanced quality control procedures in the device manufacturing process. A gravity-driven flow test provides a reasonably quick test of both resistance and closing pressure, which might be useful as a manufacturing line test. The syringe-driven flow test requires more time but provides additional insight into device performance, and, therefore, might be useful as a design validation test.