Microbial keratitis after Boston type I keratoprosthesis implantation: incidence, organisms, risk factors, and outcomes

Abstract

Purpose: To identify the incidence of and risk factors for microbial keratitis after implantation of the Boston type I keratoprosthesis (Massachusetts Eye and Ear Infirmary, Boston, MA).

Design: Retrospective, single-surgeon consecutive case series.

Participants: A total of 105 patients (125 keratoprosthesis procedures in 110 eyes) who underwent Boston type I keratoprosthesis implantation at the Jules Stein Eye Institute between May 1, 2004, and April 1, 2012.

Methods: Data regarding ocular history, relevant intraoperative data, postoperative management, and outcomes were collected for each procedure. Risk factor analyses were performed using the Fisher exact test, log-rank test, and hazard ratio (HR).

Main outcome measures: Incidence of microbial keratitis, organisms responsible, risk factors, and outcomes.

Results: During the period under review, 20 presumed infectious infiltrates were diagnosed in 15 eyes (13.6%) of 15 patients (14.3%), for a rate of 0.073 infections per eye-year. The rate of culture-positive bacterial keratitis was 0.022 infections per eye-year, and the rate of culture-positive fungal keratitis was 0.015 infections per eye-year. Topical vancomycin use, topical steroid use, and contact lens wear did not increase the incidence of infectious keratitis, but prolonged vancomycin use was associated with an increased risk for fungal keratitis and infectious keratitis overall. Persistent corneal epithelial defect formation also was associated with an increased incidence of fungal keratitis and infectious keratitis overall. There were no cases of endophthalmitis resulting from infectious keratitis.

Conclusions: Infectious keratitis develops in 13.6% of eyes after keratoprosthesis implantation, with a similar rate of culture-positive bacterial and fungal keratitis. The observed rate of microbial keratitis suggests the need for additional topical antimicrobial prophylaxis after keratoprosthesis implantation in eyes at higher risk, such as those with persistent corneal epithelial defect formation or prolonged vancomycin use.