title: In vitro flow testing of glaucoma drainage devices.
abstract: OBJECTIVE
  The study was intended to determine methods that could evaluate in vitro the flow characteristics of glaucoma drainage devices.
  
  
  METHODS
  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
  Results show a wide variation in device performance, indicating a strong need for enhanced quality control procedures in the device manufacturing process.
  
  
  CONCLUSIONS
  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.
authors.affiliation: U.S. Food and Drug Administration, Rockville, Maryland 20852, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Porter
authors.forename: C H
authors.initials: CH
authors.lastname: Krawczyk
authors.forename: R F
authors.initials: RF
authors.lastname: Carey
mesh_terms: D004322:Drainage / Q000592:standards*; D018463:Filtering Surgery / Q000295:instrumentation*; D005901:Glaucoma / Q000601:surgery; D006112:Gravitation; D066298:In Vitro Techniques; D007260:Infusion Pumps; D007552:Isotonic Solutions; D011312:Pressure; D011786:Quality Control
chemical_list: D007552:Isotonic Solutions