title: Comparison of polypropylene and silicone Ahmed Glaucoma Valves.
abstract: OBJECTIVE
  To evaluate and compare the clinical outcomes after implantation of the silicone plate and the polypropylene plate Ahmed Glaucoma Valves.
  
  
  METHODS
  Prospective, multicenter, comparative series.
  
  
  METHODS
  A total of 132 patients with uncontrolled glaucoma were treated with either the silicone or polypropylene Ahmed Glaucoma Valve implant.
  
  
  METHODS
  Success was defined according to 2 criteria: (1) intraocular pressure (IOP) of 6 mmHg or more or 21 mmHg or less, and (2) IOP reduction of at least 30% relative to preoperative values. Eyes requiring further glaucoma surgery, including cyclophotocoagulation, or showing loss of light perception were classified as failures.
  
  
  RESULTS
  Average follow-up was 12.8 months (range, 6-30 months) for the silicone plate group and 14.5 months (range, 6-30 months) for the polypropylene plate group (P = 0.063). At the last follow-up examination, the mean IOP was 13.8+/-3.9 mmHg and 17.3+/-6.5 mmHg (P<0.0001) and the mean number of antiglaucoma medications was 1.9+/-1.3 and 2.1+/-1.4 (P = 0.48) in the silicone plate and polypropylene plate groups, respectively. The life-table success rates for the silicone plate and polypropylene plate groups were 94.2% and 83.2% at 12 months and 82.4% and 56.7% at 24 months by definition 1, respectively (P = 0.035). When an IOP reduction of at least 30% was used for success criterion (definition 2), probabilities of success were 89.5% and 71.7% at 12 months and 78.3% and 68.5% at 24 months in the silicone and the polypropylene plate groups, respectively (P = 0.012). Visual outcomes were comparable between the 2 groups. However, complications including Tenon's cyst were observed more frequently in the polypropylene plate than in the silicone plate group (P<0.05).
  
  
  CONCLUSIONS
  The silicone Ahmed Glaucoma Valve (model FP7) showed improved IOP reduction compared with the polypropylene (model S2) implant. Differences observed in mean IOP, success rate, and complications suggest that plate material may influence clinical outcome.
authors.affiliation: Hamilton Eye Institute, Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Ishida
authors.forename: Peter A
authors.initials: PA
authors.lastname: Netland
authors.forename: Vital P
authors.initials: VP
authors.lastname: Costa
authors.forename: Lineu
authors.initials: L
authors.lastname: Shiroma
authors.forename: Baseer
authors.initials: B
authors.lastname: Khan
authors.forename: Iqbal Ike K
authors.initials: II
authors.lastname: Ahmed
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003240:Connective Tissue Diseases / Q000209:etiology; D005128:Eye Diseases / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D005901:Glaucoma / Q000503:physiopathology / Q000601:surgery*; D020327:Glaucoma Drainage Implants / Q000009:adverse effects; D006801:Humans; D007429:Intraocular Pressure; D015993:Life Tables; D008297:Male; D008875:Middle Aged; D011126:Polypropylenes; D011446:Prospective Studies; D012828:Silicones; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D011126:Polypropylenes; D012828:Silicones