Excimer laser experimental keratectomy. Ultrastructural study.

Excimer lasers have been shown to produce precise etching and clean incisions of the cornea. On two freshly enucleated human eyes radial incisions and a myopic keratomileusis were performed with a specially designed delivery system. The cornea was then studied by transmission and scanning electron microscopy. The surface of the irradiated area was extraordinarily smooth and clean with a precision greater than 10 nm. The epithelial cells were literally cleaved by the ablation process. The cytoplasm and the nucleus were cut without any damage to the other part of the cell and no disturbance of the cells proximal to the incision. The corneal stroma was cut in a regular and smooth fashion, and the aspects observed with the scanning electron microscope differed mainly from the surface observed after an incision made with a diamond knife. The excimer laser allowed optimal conditions for quick and safe wound healing but the long-term effects on the epithelial cells must be evaluated by further studies.