Progress in the development of a synthetic corneal onlay.

PURPOSE This study evaluated an improved perfluoropolyether polymer formulation designed for use as a corneal onlay to correct refractive error. METHODS Collagen I coated perfluoropolyether lenticules were implanted in feline corneas exposing a 6-mm diameter area of lenticule surface for epithelial growth. A parallel series of sham-wounded corneas were also studied. All corneas were monitored clinically for 4 or 8 weeks after surgery when animals were terminated and corneas used for histology with light and electron microscopy. RESULTS Postoperative epithelial growth began on days 1 and 2. Lenticule surfaces were fully epithelialized by days 5 to 11. Corneas remained clear, and the lenticules maintained epithelial cover until the designated time points. Histology of the implanted corneas showed that the lenticules were well tolerated by the cornea. Each lenticule was fully covered by a multilayered epithelium with microvilli, desmosomes, and a differentiated basal cell layer. Epithelial adhesive structures (basal lamina, hemidesmosomes, and anchoring fibrils) had assembled at the tissue-lenticule interface. CONCLUSIONS Collagen coated perfluoropolyether lenticules implanted in the feline cornea supported the growth of a stable stratified squamous epithelium. These encouraging results are a step further in the development of a corneal onlay for correction of refractive error.