title: Clinical experience with the Ahmed Glaucoma Valve implant in eyes with prior or concurrent penetrating keratoplasties.
abstract: OBJECTIVE
  To evaluate the Ahmed Glaucoma Valve implant, an aqueous shunting device with a unidirectional valve mechanism, in eyes with concurrent or prior penetrating keratoplasties.
  
  
  METHODS
  Thirty-one eyes of 31 consecutive patients had placement of an Ahmed Glaucoma Valve implant. Median patient age was 65.1 years (range, 17.2 to 103.4 years). The main outcome measure was time after surgery without failure. Success was defined as no additional glaucoma surgeries or devastating visual complications, no new corneal graft failure, an intraocular pressure greater than or equal to 5 mm Hg on the last two follow-up examinations, and reduction in intraocular pressure. For eyes with preoperative intraocular pressure greater than 22 mm Hg, an average intraocular pressure of less than 22 mm Hg on the last two follow-up examinations was required. For eyes with preoperative intraocular pressure of less than 22 mm Hg, an intraocular pressure lowered by at least 20% from preoperative values was required.
  
  
  RESULTS
  Cumulative probabilities of success at 12 and 20 months (mean +/- SD) were 75.4% +/- 8.2% and 51.5% +/- 11.4%, respectively. Eleven of 31 eyes were failures. The risk of failure in eyes with prior infectious keratitis or keratouveitis was estimated to be 5.8 times greater than that associated with eyes that underwent penetrating keratoplasties for other reasons (P = .009).
  
  
  CONCLUSIONS
  Twelve- and 20-month success rates of the implant in eyes with prior or concurrent penetrating keratoplasties were comparable to those of other drainage devices. Eyes with prior infectious keratitis or keratouveitis were at increased risk of failure.
authors.affiliation: Jules Stein Eye Institute, UCLA School of Medicine, USA. coleman@jsei.ucla.edu
authors.forename: A L
authors.initials: AL
authors.lastname: Coleman
authors.forename: B J
authors.initials: BJ
authors.lastname: Mondino
authors.forename: M R
authors.initials: MR
authors.lastname: Wilson
authors.forename: R
authors.initials: R
authors.lastname: Casey
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016039:Corneal Transplantation; D004322:Drainage / Q000379:methods*; D004868:Equipment Failure; D005260:Female; D005901:Glaucoma / Q000188:drug therapy / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007429:Intraocular Pressure; D015948:Keratoplasty, Penetrating; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D019736:Prostheses and Implants; D012086:Reoperation; D013997:Time Factors; D016896:Treatment Outcome; D014792:Visual Acuity