title: Comparison of silicone and polypropylene Ahmed Glaucoma Valve implants.
abstract: OBJECTIVE
  To compare the efficacy and safety of silicone and polypropylene Ahmed Glaucoma Valves (AGVs) in patients with refractory glaucoma.
  
  
  METHODS
  A retrospective chart review of 180 eyes of 166 patients who underwent AGV implantation with a minimum follow-up period of 3 months was performed. All patients who underwent implantation of either the AGV model S-2 (polypropylene) or model FP-7 (silicone) were included, unless previous laser cyclophotocoagulation had been performed. The primary outcome measures were the change in intraocular pressure (IOP) and visual acuity after surgery and the rate of postoperative complications.
  
  
  RESULTS
  No significant differences were seen in the baseline characteristics of patients in each group. Baseline IOP was statistically equivalent in the 2 groups (silicone =33.8+/-11.9 mm Hg, polypropylene=33.0+/-10.3 mm Hg, P=0.6). A significant reduction in IOP from baseline was achieved after both silicone and polypropylene AGV implantation (silicone =-17.7+/-11.8 mm Hg, polypropylene =-17.7+/-11.3 mm Hg, both P<0.00005). However, there was no statistically significant difference in IOP decrease between the 2 groups at any follow-up visit (all P>0.09). The mean number of postoperative antiglaucoma medications was also similar in the silicone and the polypropylene AGV groups at each time point (all P>0.2). The rate of complications and the change in visual acuity did not differ between the 2 groups (P>0.6 and P>0.3, respectively).
  
  
  CONCLUSIONS
  Silicone and polypropylene AGVs have similar results with respect to both safety and efficacy in the treatment of patients with refractory glaucoma.
authors.affiliation: Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Maria Vitoria Oliveira Moura
authors.initials: MV
authors.lastname: Brasil
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Rockwood
authors.forename: Scott D
authors.initials: SD
authors.lastname: Smith
mesh_terms: D000959:Antihypertensive Agents / Q000008:administration & dosage; D001672:Biocompatible Materials; D005260:Female; D005901:Glaucoma / Q000601:surgery*; D020327:Glaucoma Drainage Implants; D006801:Humans; D007429:Intraocular Pressure; D015948:Keratoplasty, Penetrating; D008297:Male; D008875:Middle Aged; D011126:Polypropylenes; D011183:Postoperative Complications; D019919:Prosthesis Implantation; D012189:Retrospective Studies; D012826:Silicone Elastomers; D014065:Tonometry, Ocular; D016896:Treatment Outcome; D014792:Visual Acuity; D014821:Vitrectomy
chemical_list: D000959:Antihypertensive Agents; D001672:Biocompatible Materials; D011126:Polypropylenes; D012826:Silicone Elastomers