title: Valve membrane adhesion as a cause of Ahmed glaucoma valve failure.
abstract: OBJECTIVE
  The purpose of this study was to describe a possible mechanism of failure of the Ahmed glaucoma valve (AGV; New World Medical, Rancho Cucamonga, CA).
  
  
  METHODS
  Two AGVS that failed to control intraocular pressure (IOP) were examined. In vivo examination consisted of unroofing the capsule surrounding the implant and injecting fluorescein-stained balanced salt solution into the tube. In one case the entire implant was removed and examined in vitro, and in the other case only the valve portion was removed.
  
  
  RESULTS
  No flow in either case extended beyond the valve. In both cases, the membrane valve system was found to be fused and could not be pulled apart.
  
  
  CONCLUSIONS
  Failure of the AGV may occur due to adhesion of the valve membranes.
authors.affiliation: Department of Ophthalmology and Visual Science, University of Texas Health Science Center, Houston, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Feldman
authors.forename: S M
authors.initials: SM
authors.lastname: el-Harazi
authors.forename: G
authors.initials: G
authors.lastname: Villanueva
mesh_terms: D000867:Anterior Chamber / Q000601:surgery; D004322:Drainage / Q000295:instrumentation*; D005260:Female; D019793:Fluorescein; D005452:Fluoresceins; D005500:Follow-Up Studies; D005901:Glaucoma / Q000601:surgery*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000209:etiology; D011183:Postoperative Complications; D019736:Prostheses and Implants / Q000009:adverse effects*; D011475:Prosthesis Failure; D012826:Silicone Elastomers / Q000009:adverse effects*
chemical_list: D005452:Fluoresceins; D012826:Silicone Elastomers; D019793:Fluorescein