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Clinical results after subepithelial photorefractive keratectomy (LASEK).

PURPOSE
To study the results of photorefractive keratectomy (PRK) after creation of an epithelial flap and replacement of the flap after ablation (LASEK).


METHODS
PRK was performed with the Nidek EC-5000 excimer laser. The technology of subepithelial PRK was developed in experiments in vitro in 10 pig eyes and six human eyes. The experiments in vivo were carried out in eight eyes of four rabbits. In patients, subepithelial PRK was carried out in 12 eyes with high myopia, best spectacle-corrected visual acuity of 20/30 and below. LASIK, ordinary PRK, or transepithelial PRK were performed in the second eye to act as a control.


RESULTS
The basic steps of subepithelial PRK include creation of an epithelial flap, refractive ablation, and subsequent repositioning of the epithelial flap. In the clinical trial, creation of an epithelial flap was easy in five (41.7%) eyes, moderate in four (33.3%) eyes, and difficult in three (25.0%) eyes. No pain occurred in six (50%) eyes, some discomfort in four (33.3%) eyes, and pain in two (16.7%) eyes. After subepithelial PRK, visual and refractive results were similar with both LASIK and PRK. The common components of ordinary PRK, transepithelial PRK, and subepithelial PRK are removal of Bowman's layer and epithelium. The advantages and disadvantages of subepithelial PRK are considered.


CONCLUSION
Subepithelial PRK (LASEK) has the potential for widespread use in clinical practice, but further development of special instruments and techniques would be helpful.