Retroprosthetic membrane and risk of sterile keratolysis in patients with type I Boston Keratoprosthesis.

PURPOSE: To evaluate whether retro-backplate retroprosthetic membrane is correlated with risk of melt in patients with a type I Boston Keratoprosthesis (KPro).

DESIGN: Retrospective, observational case series.

METHODS: Study of 50 eyes of 47 patients with type I Boston KPro and postoperative anterior segment optical coherence tomography (AS OCT) imaging performed at the University of Illinois at Chicago. Main outcome measures were presence of retro-backplate membrane and development of melt requiring explantation. For eyes with melt, membrane thickness was measured using the AS OCT images obtained at the last visit before melt occurred. For eyes without melt, the last available AS OCT images were used for measurement.

RESULTS: AS OCT evidence of a retro-backplate membrane was observed in 100% of eyes that melted and in 34.1% of eyes that did not (P = .0034; risk ratio, 2.9; 95% confidence interval, 1.9 to 4.4). Retro-backplate membrane thickness in the melt group was 278 μm versus 193 μm in the nonmelt group (P = .025).

CONCLUSIONS: The retro-backplate portion of a retroprosthetic membrane is to be differentiated from the retro-optic portion seen at the slit lamp. The retro-backplate membrane as shown by AS OCT imaging is correlated with an increased risk of sterile keratolysis, possibly because of impedance of nutritional support from the aqueous humor. Further studies are needed to better standardize the AS OCT measurements of retro-backplate membranes as well as to identify early interventions to prevent progression of thin membranes once identified on AS OCT.