Experimental radial thermokeratoplasty in rabbits

Radial thermokeratoplasty is a new technique designed to reduce hyperopia. We evaluated the histopathological effect at 2, 4, and 30 days following radial thermokeratoplasty in rabbit corneas. Surgical complications included variable-sized coagulations and microperforations in two eyes. Light microscopy disclosed that the burns were 90% in depth and healing occurred by epithelial ingrowth. The stroma surrounding the coagulation was acellular early but keratocyte repopulation was apparent by 30 days. A retrocorneal membrane four to five cells thick was noted at the early time points; however, by 30 days only a double layer of spindle-shaped cells remained. By electron microscopy, damage to surrounding endothelial cells was estimated to be 300 microns (from the center of the coagulation). Our results suggest that radial thermokeratoplasty, which utilizes a temperature of 600 degrees C placed within the cornea to a depth of 90%, will cause significant damage to the corneal endothelium beneath and surrounding the coagulation site.