The Boston keratoprosthesis in the management of corneal limbal stem cell deficiency

To report the outcomes of the Boston type I keratoprosthesis (Massachusetts Eye and Ear Infirmary, Boston, MA) in the management of corneal limbal stem cell deficiency (LSCD).

A retrospective review of all cases of keratoprosthesis implantation performed by a single surgeon (A.J.A.) between May 1, 2004, and March 31, 2010. Procedures performed for the management of LSCD were identified, and data were collected regarding the patients' ocular history, surgical procedure(s) performed, and postoperative outcomes, including interval visual acuities, retention, complications, and required surgical procedures. The outcome data from patients with LSCD were compared with those of individuals who underwent keratoprosthesis implantation for indications other than LSCD.

Twenty-eight keratoprostheses were performed in 23 eyes of 22 patients with LSCD. The most common indications for surgery were chemical injury (7 eyes) and Stevens-Johnson syndrome (6 eyes). Preoperative corrected distance visual acuity (CDVA) was better than counting fingers in 4% of eyes with LSCD and in 9% of eyes without LSCD. Postoperative CDVA was 20/50 or better in 69%, 88%, and 67% of eyes with LSCD at 1, 2, and 3 years after keratoprosthesis implantation, respectively. Each of these percentages is higher than the percentage of eyes without LSCD obtaining CDVA of 20/50 or better at each time point. Whereas the retention failure rate in eyes with LSCD (0.148/eye-year) was higher than the rate in eyes without LSCD (0.114/eye-year), when eyes with Stevens-Johnson syndrome were excluded from the LSCD group, the non-Stevens-Johnson syndrome LSCD retention failure rate (0.056/eye-year) was half that of the non-LSCD group. The most common postoperative complications in eyes with LSCD were persistent corneal epithelial defect (PED) formation (56.5% of eyes) and sterile corneal necrosis (30%), whereas retroprosthetic membrane formation (46%) was the most common postoperative complication in eyes without LSCD, followed by PED formation (23%). The development of a PED was found to be a significant risk factor for sterile corneal stromal necrosis and infectious keratitis.

Boston type I keratoprosthesis implantation results in a significant improvement in CDVA in the majority of patients with LSCD, with CDVA of 20/50 or better in more than two-thirds of eyes up to 3 years after surgery. PED formation is the most common postoperative complication in eyes with LSCD and is associated with an increased rate of sterile stromal necrosis and a lower retention rate in eyes undergoing keratoprosthesis implantation for immune-mediated LSCD. These results support the use of the Boston type I keratoprosthesis in managing bilateral, non-immune-mediated LSCD.