Graft Adhesion and Recovery of Corneal Function after Posterior Lamellar Keratoplasty

ABSTRACT

PURPOSE: Posterior lamella keratoplasty has been described as a new procedure to treat corneal conditions involving endothelial dysfunction by selective transplantation of only the posterior corneal tissue composed of the endothelium, Descemet membrane, and posterior stroma. This study has been conducted to evaluate the recovery of endothelial function and adhesion mechanism of transplanted posterior corneal tissue to the donor stroma after posterior lamella keratoplasty. METHODS: Dog corneal endothelium and posterior stroma were transplanted to recipient dog cornea stripped of endothelium and posterior stroma. The recovery of endothelial function and corneal thickness were measured by specular microscopy; pachymetry and slit lamp examination were done immediately after posterior lamella keratoplasty and at 1, 2, 4, 8 weeks post-operative. Eight weeks after operation, enucleation was performed and the histopathologic changes in the transplanted area of enucleated eyes were examined by light microscopy, fluorescent microscopy, and electron microscopy. RESULTS: Corneal thickness, endothelial function, and corneal transparency were recovered by the end of experiment. The newly produced collagen fibrils were absent at the corneal posterior flap and anterior stromal bed interface. The collagen fibrils adjacent to the flap interface were irregularly arranged and morphologically transformed in some cases (2 of 8 cases) and were linearly arranged in a parallel manner in others (6 of 8 cases). CONCLUSIONS: It can be suggested that the stability of transplanted posterior corneal flap is maintained by incomplete wound healing and recovery of corneal endothelial function.