Retroprosthetic Membrane Formation in Boston Keratoprosthesis: A Case–Control-Matched Comparison of Titanium Versus PMMA Backplate

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Purpose:Retroprosthetic membrane (RPM) formation is the most common complication after Boston type 1 keratoprosthesis (KPro) implantation. It affects visual acuity and can predispose to corneal melt. Two KPro backplate materials are available: titanium and polymethyl methacrylate (PMMA). This study investigates the influence of the KPro backplate material on visually significant RPM formation.Methods:A retrospective case–control-matched study involving 40 patients; 20 eyes implanted with a titanium backplate KPro were case-matched with 20 eyes implanted with a PMMA backplate KPro between 2007 and 2015 with 1-year minimum follow-up.Results:The mean follow-up duration was 28.1 ± 8.9 and 53.6 ± 24.3 months in the titanium and PMMA groups, respectively. At 12 months postoperatively, 7 eyes with titanium and 6 eyes with PMMA backplates developed a visually significant RPM. By the end of the study, a total of 11 eyes with titanium and 9 eyes with PMMA KPros developed a visually significant RPM. There was no statistically significant difference between both groups. Three of 11 eyes with titanium KPros that had a visually significant RPM required surgical membranectomy, whereas all eyes with PMMA KPros were successfully treated with the yttrium-aluminum-garnet laser. Recurrence of RPMs was found in 7/11 eyes in the titanium group and 2/9 eyes in the PMMA group with no statistical significance.Conclusions:Titanium backplate KPros do not significantly reduce RPM formation compared with PMMA backplate KPros in a case–control-matched setting. A larger prospective study is warranted to evaluate comparative long-term performance and guide newer designs.

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