Histopathological and Immunohistochemical Analysis of Melt-Associated Retroprosthetic Membranes in the Boston Type 1 Keratoprosthesis

IMPORTANCE Retroprosthetic membrane (RPM) formation is the most common complication associated with the Boston type 1 keratoprosthesis and has been associated with corneal melt. OBJECTIVE To identify the histological and immunohistochemical characteristics of RPMs associated with corneal melt. DESIGN SETTING. AND PARTICIPANTS Observational histopathological case series at a tertiary eye care referral center among patients who underwent Boston type 1 keratoprosthesis explantation because of donor corneal melt at the Illinois Eye and Ear Infirmary between January 1, 2011, and January 1, 2012. EXPOSURES Seven RPM specimens from 7 eyes were stained with hematoxylin-eosin, cytokeratin 7, cytokeratin AE1/3, smooth muscle actin, vimentin, and CD34. Light microscopy was used to evaluate specimens for inflammation and epithelial ingrowth. XY-karyotyping using fluorescence in situ hybridization was performed on 4 specimens with known donor-recipient sex mismatch. MAINN OUTCOMES AND MEASURE Histological and immunohistochemical characteristics of RPMs. RESULTS Inflammatory cells were present in 4 of 7 RPMs. In 3 of 4.sex-mismatched specimens, tissue XY-karyotyping of the RPM interphase cells was consistent with the host sex karyotype. The fourth specimen showed a mixture of recipient-type and donor-type cells. CONCLUSIONS AND RELEVANCE Melt-associated RPMs show variable degrees of inflammation. Most membranes seem to originate from a proliferation of host cells, but donor tissue may contribute in some cases.