Risk Factors for the Development of Retroprosthetic Membranes with Boston Keratoprosthesis Type 1 : Multicenter Study Results

ObjectiveThe 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.DesignCohort study.ParticipantsThe 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.MethodsForms reporting preoperative, intraoperative, and postoperative parameters were prospectively collected and subsequently analyzed at a central data collection site.Main Outcome MeasuresThe primary outcome was the presence or absence of an RPM during the follow-up period.ResultsThe 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).ConclusionsFormation 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.Financial Disclosure(s)The authors have no proprietary or commercial interest in any of the materials discussed in this article.