title: Evaluation of success after second Ahmed glaucoma valve implantation.
abstract: OBJECTIVE
  To evaluate the outcome of the second Ahmed glaucoma valve (AGV) surgery in eyes with failed previous AGV surgery.
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  Following chart review, 36 eyes of 34 patients with second AGV implantation were enrolled in this study. The primary outcome measure was surgical success defined in terms of intraocular pressure (IOP) control using two criteria: Success was defined as IOP ≤21 mmHg (criterion 1) and IOP ≤16 mmHg (criterion 2), with at least 20% reduction in IOP, either with no medication (complete success) or with no more than two medications (qualified success). Kaplan-Meier survival analysis was used to determine the probability of surgical success.
  
  
  RESULTS
  The average age of the patients was 32.7 years (range 4-65), and the mean duration of follow-up was 21.4 months (range 6-96). Preoperatively, the mean IOP was 26.94 mmHg (standard deviation [SD] 7.03), and the patients were using 2.8 glaucoma medications on average (SD 0.9). The mean IOP decreased significantly to 13.28 mmHg (SD 3.59) at the last postoperative visit (P = 0.00) while the patients needed even fewer glaucoma medications on average (1.4 ± 1.1, P = 0.00). Surgical success of second glaucoma drainage devices (Kaplan-Meier analysis), according to criterion 1, at 6, 12, 18, and 42 months was 94%, 85%, 80%, and 53% respectively, and according to criterion 2, was 94%, 85%, 75%, and 45%, respectively.
  
  
  CONCLUSIONS
  Repeated AGV implantation seems to be a safe modality of treatment with acceptable success rate in cases with failed previous AGV surgery.
authors.forename: Naveed
authors.initials: N
authors.lastname: Nilforushan
authors.affiliation: Eye Research Center, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Yadgari
authors.forename: Anis Alsadat
authors.initials: AA
authors.lastname: Jazayeri
authors.forename: Nasser
authors.initials: N
authors.lastname: Karimi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D018463:Filtering Surgery / Q000379:methods*; D005500:Follow-Up Studies; D005901:Glaucoma / Q000503:physiopathology / Q000601:surgery*; D020327:Glaucoma Drainage Implants; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D014792:Visual Acuity; D055815:Young Adult