Risk Factors for the Development of Retroprosthetic Membranes with Boston Keratoprosthesis Type 1

Monday, October 20, 2014

Multicenter Study Results
Christopher J. Rudnisky, MD, MPH,1 Michael W. Belin, MD,2 Amit Todani, MD,3,4
Khalid Al-Arfaj, MD,3,4,5
Jared D. Ament, MD,3 Brian J. Zerbe, MD,4,6 Joseph B. Ciolino, MD,3,4 for the Boston
Type 1 Keratoprosthesis
Study Group*

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.

Design: Cohort study.

Participants: 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.

Main Outcome Measures: 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.

Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article. Ophthalmology 2012;119:951–955 © 2012 by the American Academy of Ophthalmology.
*Group members listed in Appendix 1.

The Boston keratoprosthesis, developed at the Massachusetts Eye and Ear Infirmary and approved by the US Food and Drug Administration in 1993, is used in eyes at high risk for penetrating keratoplasty (PK) failure. Over the years, the device underwent several modifications to improve retention and, subsequently, is now used by ophthalmologists worldwide. However, there are a number of significant complications that can occur in eyes that have received a keratoprosthesis, including retroprosthetic membrane (RPM),1–4 glaucoma,4,5 endophthalmitis,3,6 sterile vitritis, 4,7 and prosthetic failure.1–2,4,8 One of the most common complications is the development of RPM, reported to affect between 254 and 65%3 of cases. Although not every patient requires treatment for RPM, which includes Nd:YAG laser membranotomy, some require surgical removal because the RPM can become too thick and dense to treat with laser. Zerbe et al4 reported an RPM incidence of 25% (35/141 eyes); 74% (n _ 25) of the affected eyes were treated with ND:YAG laser, 11.4% (n _ 4) were treated surgically, and 17% were observed. The etiology of RPM is unknown; authors have reported that the performance of other intraocular surgery at the time

© 2012 by the American Academy of Ophthalmology ISSN 0161-6420/12/$–see front matter 951 Published by Elsevier Inc. doi:10.1016/j.ophtha.2011.11.030

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