Conductive keratoplasty: histological study of human corneas.

PURPOSE To determine the morphologic changes in human corneas over time following radiofrequency-based conductive keratoplasty (CK) treatment. DESIGN Prospective, observational case series. METHODS In a single-center study six human corneas of six patients with localized peripheral keratoconus underwent CK treatment followed by penetrating keratoplasty. Three spots were applied in the periphery of each cornea (6 mm optical zone). Corneal buttons were examined with light and electron microscopy at different postoperative intervals up to 6 months post-CK. RESULTS In samples assessed on day one post-CK, small areas of detachment between the basal layer of epithelial cells and Bowman's layer were observed. At 1 week after the CK procedure, the epithelium appeared almost normal. Endothelium and Descemet's membrane had no alterations. In all samples, thermally induced misconfiguration of collagen fibers, described as "crumpled" changes of collagen layers, was observed reaching 75% to 80% of the stromal depth. The area of alterations had a cylindrical shape with a diameter of 120 mum. CONCLUSIONS The conductive keratoplasty procedure produced collagen "crumpling and splitting" changes in human corneas, which were observed during the follow-up of 6 months. Areas adjacent to treatment site were minimally damaged.