Wound Anatomy After Type 1 Boston KPro Using Oversized Back Plates

Abstract

To compare the anatomy of the graft-host junction and anterior chamber angle after Boston Keratoprosthesis (KPro) placement using oversized (9.5-mm) and standard (8.5-mm) back plates. Six patients with 9.5-mm titanium back plates and 10 patients with 8.5-mm titanium back plates were imaged by anterior segment optical coherence tomography 6 to 12 months after KPro placement. The location of the graft-host junction in relation to the back plate, the corneal thickness at the graft-host junction, and the anterior chamber angle were assessed. The clinical outcomes and incidence of retroprosthetic membrane (RPM) formation in this cohort were retrospectively evaluated. The oversized back plates completely covered the graft-host junction in all quadrants, allowing the complete apposition of the posterior surface of the carrier graft with the host cornea, with decreased graft-host junction wound thickness. The standard back plates covered the posterior aspect of the carrier graft but not the graft-host junction or the host cornea, resulting in a significantly thicker graft-host junction. None of the patients with larger back plates developed a significant RPM during a 12-month follow-up period. One patient with a larger back plate developed a corneal melt at the KPro stem as a result of chronic exposure. Oversized KPro back plates effectively cover the graft-host junction without any adverse effects on angle anatomy or wound healing. This may be a strategy to provide better wound apposition, reduce RPM formation, and reduce angle closure from iris synechiae to the wound.