Corneal ultrastructure after excimer laser keratectomy

Abstract

The Argon fluoride excimer laser emits light at 193nm. At a fluence of 500mJ/CM2, one micron of organic tissue should be removed. This removal occurs by the disruption of chemical bonds rather than the normal heat vaporization seen with other types of lasers. These characteristics should allow the use of this laser in performing precise removal of superficial corneal scars and opacities as well as inducing changes in corneal curvature for refractive corrections. In our studies we will report the ultrastructural changes induced in both primates and man following excimer laser treatment.Following excimer laser treatment, the primates were followed for two years and the corneas removed for morphological studies. The human specimens were taken at various times after excimer treatment for clinical reasons, all having to do with unfavorable outcomes. All human specimens were taken at the time of transplantation of a new cornea to these eyes. The specimens were fixed with 2% paraformaldehyde and 2% gluderaldehyde in cacodylate buffer at pH 7.3. After fixation, these specimens were dehydrated, imbedded in Spurr epoxy resin, then sectioned and examined ultrastructurally.