Epi-LASIK may be an alternative to LASEK

NUREMBERG, Germany — Mechanical separation of the epithelium before laser ablation may be preferable to the use of alcohol to loosen the epithelium, according to a speaker here.

Studies show that mechanical manipulation of the corneal surface tissue does not affect normal cell morphology as does separation using either of two alcohol concentrations, said Ioannis Pallikaris, MD, who gave the Innovator's Lecture here at the German Ophthalmic Surgeons meeting.

"Epi-LASIK is a treatment method where the preparation of an epithelial flap occurs without the use of alcohol, but by purely mechanical means," Prof. Pallikaris said. "The epithelium is separated by a subepithelial separator (SES), similar to a keratome. Microscopy shows a very nice demarcation between what is being separated."

Prof. Pallikaris described a study in which 10 eyes of 10 patients underwent de-epithelialization using two techniques: Six eyes had the epithelial layer mechanically separated with a customized instrument. Four underwent conventional laser epithelial keratomileusis (LASEK) with alcohol concentrations of 15% and 30%.

He said patients undergoing the LASEK procedure have a lower rate of haze than those undergoing photorefractive keratectomy, but alcohol toxicity remains problematic. Toxicity is dependent upon the alcohol dose and time of application, Prof. Pallikaris said.

A published study indicates that 80% alcohol for 20 seconds is sufficient to dissect the epithelium, he said, while another study shows that 18% alcohol requires a maximum exposure time of 40 seconds for patients with firm epithelial layers.

Prof. Pallikaris performs the separation at the stromal surface. He said epi-LASIK has been studied in human eyes as well as in rabbits. The eyes were followed for 24 hours and longer. Prof. Pallikaris reported that the epithelial cells seemed to be vital without any obvious morphological changes. The epithelial flap retained its normal multilayer structure.