Alcohol debridement of the corneal epithelium in PRK and LASEK: an electron microscopic study.

Abstract

To determine the plane of cleavage of the corneal epithelium and smoothness of underlying stroma, after alcohol debridement in photorefractive keratectomy (PRK) and laser subepithelial keratectomy (LASEK). The epithelial flap from six patients undergoing alcohol delamination of corneal epithelium before PRK and the epithelium and stroma from three eye bank donor eyes were fixed and processed for transmission (TEM) and scanning electron microscopy (SEM). The smoothness of the underlying stroma was studied by SEM and the plane of cleavage was determined by morphologic examination and morphometric measurements of basement membrane attached to the epithelial flap, using image-analysis software. A very smooth stromal bed, ideal for PRK was seen in the stroma of all three eye bank donor eyes after alcohol delamination. The plane of cleavage was determined to be at the hemidesmosomal attachments, including the most superficial part of the lamina lucida of the basement membrane. Alcohol delamination of the corneal epithelium before PRK or LASEK consistently results in a very smooth cleavage at the level of the hemidesmosomal attachments, including the superficial lamina lucida. It leaves behind a very smooth surface, which is ideal for PRK. It also allows for an intact epithelial flap to be lifted as a sheet from the corneal surface and hence is ideally suited for the LASEK technique.