Histopathologic Evaluation of Polymer Supports for Pintucci-type Keratoprostheses: An Animal Study

PURPOSE: To report histopathological findings for different types of polymers proposed as support for a Pintucci-type keratoprosthesis. METHODS: Six polymers, including three types of polyesters ([Formula: see text] 1-3), one type of polytetrafluoroethylene (PTFE, [Formula: see text] 4), polyethylene ([Formula: see text] 5), and expanded polytetrafluoroethylene (ePTFE, [Formula: see text] 6) were evaluated. Four samples of each material were placed under the orbicularis oculi muscles of 12 rabbits. After five weeks, the samples were removed and evaluated histopathologically. Fibrovascular tissue ingrowths were investigated in terms of tissue penetration depth into the materials (graded as none, mild, moderate, and intense) and fibrovascular ingrowth area at the ultimate level of tissue penetrance. ImageJ software was used to calculate fibrovascular tissue area between the material fibers, and the mean area values were compared between the materials. RESULTS: Polyester materials [Formula: see text] 1 and [Formula: see text] 3 demonstrated intense fibrovascular tissue penetration with a large fibrovascular ingrowth area; no overt tissue ingrowth was observed into material #6. The mean area of penetrated fibrovascular tissues was significantly different between materials ([Formula: see text] < 0.001). Materials [Formula: see text] 2, [Formula: see text] 4, and [Formula: see text] 5 showed moderate fibrovascular tissue ingrowth and the area of presented fibrovascular tissue at the paracentral parts of material [Formula: see text] 4 was significantly smaller than that of materials [Formula: see text] 1 ([Formula: see text] = 0.02) and [Formula: see text] 3 ([Formula: see text] = 0.01). CONCLUSION: Two polyester materials that had relatively large pore sizes demonstrated a deep and large area of fibrovascular ingrowth. Given that material #3 is thicker and more consistent than material [Formula: see text] 1, the former can be used as the appropriate material for supporting the Pintucci-type keratoprosthesis.