Tangential corneal surface ablation with 193- and 308-nm excimer and 2936-nm erbium-YAG laser irradiation.

An argon-fluoride excimer laser operating at 193 nm was used to perform tangential, wide-area surface photoablation of the corneas of bovine eyes. Comparisons were made with similar tangential ablations performed with the use of 308-nm xenon chloride excimer laser and qi/gl 2936-nm erbium-YAG laser irradiation to evaluate potential photochemical and thermal effects. Light and transmission electron microscopy of the corneal tissue revealed minimal tissue architectural changes for ablation at 193 nm. The zone of ultrastructural change at the corneal surface with the 193-nm excimer laser was 120 nm thick. The clinical appearance of the corneal surfaces produced by the tangential ablation at 193 nm was the most satisfactory of those with the three wavelengths tested, being macroscopically smooth and glossy.