title: Risk factors for the development of retroprosthetic membranes with Boston keratoprosthesis type 1: multicenter study results.
abstract: OBJECTIVE
  The purpose of this study was to identify possible risk factors for retroprosthetic membrane (RPM) development in a large, multicenter cohort of patients receiving a Boston type 1 keratoprosthesis.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  The final analysis included 265 eyes of 265 patients who underwent implantation of a Boston keratoprosthesis type I device between January 2003 and July 2008 by 1 of 19 surgeons at 18 medical centers.
  
  
  METHODS
  Forms reporting preoperative, intraoperative, and postoperative parameters were prospectively collected and subsequently analyzed at a central data collection site.
  
  
  METHODS
  The primary outcome was the presence or absence of an RPM during the follow-up period.
  
  
  RESULTS
  The average age of patients was 63.3±19.1 years, 48.5% of the patients were female, and 52.5% of procedures were performed on the right eye. The mean follow-up time was 17.8±14.9 months. The majority (85.4%; n = 222) had undergone an average of 2.2±1.2 (range, 1-8) penetrating keratoplasties before keratoprosthesis implantation, and 38 eyes (14.6%) received a primary keratoprosthesis. The overall RPM formation rate was 31.7% (n = 84). The most significant risk factor for RPM development was infectious keratitis (as a surgical indication for keratoprosthesis surgery itself), resulting in a rate of RPM formation of 70.6%. As an independent risk factor, the hazard ratio (HR) of RPM development in these eyes was 3.20 (95% confidence interval, 1.66-6.17). Aniridia was also an independent risk factor for RPM development (HR, 3.13; 95% confidence interval, 1.10-8.89).
  
  
  CONCLUSIONS
  Formation of RPM is a common complication of keratoprosthesis surgery, occurring in approximately one-third of cases. Eyes at the highest risk of RPM development are those receiving corneal replacement for infectious keratitis and aniridia.
authors.affiliation: Department of Ophthalmology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Rudnisky
authors.forename: Michael W
authors.initials: MW
authors.lastname: Belin
authors.forename: Amit
authors.initials: A
authors.lastname: Todani
authors.forename: Khalid
authors.initials: K
authors.lastname: Al-Arfaj
authors.forename: Jared D
authors.initials: JD
authors.lastname: Ament
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Zerbe
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Ciolino
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001187:Artificial Organs; D002648:Child; D015331:Cohort Studies; D003315:Cornea; D003316:Corneal Diseases / Q000601:surgery*; D016039:Corneal Transplantation; D005260:Female; D006801:Humans; D008297:Male; D008566:Membranes / Q000473:pathology; D008875:Middle Aged; D011183:Postoperative Complications; D019736:Prostheses and Implants; D012307:Risk Factors; D055815:Young Adult