Anatomical survival and visual prognosis of Boston type I keratoprosthesis in challenging cases

To describe the outcome of patients with Boston type 1 keratoprosthesis, with regard to anatomical and visual success.

Retrospective case series of patients who underwent Boston type I keratoprosthesis surgery at the Centro de Oftalmología Barraquer in Barcelona and at the University Eye Clinic in Salzburg between May 2006 and December 2011. Sixty-seven eyes were included. Anatomical success, visual acuity, and complication rate were evaluated and correlated with the initial diagnosis.

The mean age of patients was 54 years; 62 % were male and 38 % were female. Eleven patients underwent Type I Boston Kpro implantation as a primary procedure, while the other 52 patients had previous graft failure. The most frequent diagnoses were autoimmune diseases (16 eyes), severe chemical or thermal burn (12 eyes), leukoma post-infectious keratitis (seven eyes) and bullous keratopathy (six eyes). The mean follow-up time was 26 months. Retention of the prosthesis was achieved in 95 % at 1 year and 78 % at 4.5 years. Two eyes suffered extrusion of the KPro, six underwent successful exchange of the prosthesis either due to infection, necrosis or extrusion, three KPro's had to be explantated, and two eyes ended up in enucleation due to panophthalmitis. The outcome of the autoimmune cases was similar to the group with "other diagnoses" and better than those with chemical/thermal burn. The most frequent complication was development of a retroprosthetic membrane in 21 eyes (34 %). Visual acuity (LogMAR) in the chemical/thermal burn group was 2.30 preoperatively, 0.69 at 1 year, 0.52 at 2 years and 0.39 at 3 years; in the autoimmune group visual acuity was 2.3 preoperatively, 0.65 at 1 year, 0.15 at 2 years, and 1.5 at 3 years.

Boston type 1 keratoprosthesis is a viable option for patients with repeated graft failure, even for those with challenging diagnoses such as ocular burns and autoimmune syndromes.