MYOPIC KERATOMILEUSIS BY EXCIMER-LASER ON A LATHE

BACKGROUND: We designed an excimer laser keratomileusis delivery syste m to increase the regularity of the refractive cut surface and allow g reater precision in the level and shape of the ablated zone. METHODS: A parallel faced corneal disc was produced by microkeratectomy from si x human eyes and surgical keratectomy in 12 beagle corneas. A 193-nano meter excimer laser that was used to project an oval beam onto the cor neal disc was rotated on a flat surface to ensure overlapping of the o vally ablated areas between pulses. RESULTS: Electron microscopy of ey e bank lenticules demonstrated a circular smooth regularly concave abl ation zone. Histological examination of nine clear corneas confirmed t hinning of the stroma without fibroblastic reaction and no epithelial hypertrophy. Mean preoperative corneal power of 43.15 +/- 2.18 decreas ed postoperatively to 33.61 +/- 2.34. CONCLUSIONS: The new technique o f excimer laser keratomileusis has the advantage of a cut surface smoo ther and the clear zone is devoid of the stepwise concavity and irregu larity seen in diaphragm based photoablation delivery systems.