Mid-term prognosis of type I Boston keratoprosthesis reimplantation

Aim To examine the mid-term visual and anatomical prognosis of patients who require reimplantation of a second Boston keratoprosthesis type 1 (B-KPro). Methods Retrospective observational case series of 122 patients (141 eyes) who received a B-KPro at a single institution were reviewed. Eyes that underwent a second B-KPro were included in the study. Primary endpoints were B-KPro retention, final visual acuity 20/200 and loss of light perception. Secondary endpoints included the occurrence of postoperative complications. Results Seventeen eyes (12%) required a B-KPro reimplantation. Corneal melt was the most common indication for replacement (88%). Mean follow-up time after the second B-KPro was 4.4±2.1 years. The Kaplan-Meier analysis estimated the second B-KPro retention rate at 79% over 8 years. Retroprosthetic membrane (RPM, 53%) was the most common complication. Forty-one per cent of the eyes suffered from corneal melt following their second B-KPro. One year after the second B-KPro, 47% of the patients retained a vision 20/200. Seven eyes (41.2%) lost light perception, which was secondary to an inoperable retinal detachment in five cases. Four eyes (24%) developed phthisis following inoperable retinal detachment (n=3) or endophthalmitis (n=1). Conclusion B-KPro reimplantation is a potentially sight- and globe-saving procedure for eyes with B-KPro failure, but the prognosis is guarded. B-KPro reimplantation can salvage ambulatory vision in a third of patients while another third of patients progress to loss of light perception. RPM and retinal detachment were important obstacles to visual rehabilitation while recurrent corneal melt was responsible for most cases of anatomical failure.