Safety, Efficacy and Predictability of SAT

Abstract

The surface ablation techniques have different names and origins. The most widely used method today includes the following steps: loosing and removing the epithelium with alcohol 20 % solution, thus exposing the Bowman layer, aiming the Excimer laser ablating through the Bowman and stroma, and applying MMC 0.02 % for a predefined time to prevent scarring. Some surgeons use MMC only for deeper ablations and some use it routinely. The peeled off epithelium is discarded (epithelium off technique) and the cornea is protected with a contact lens and local therapy. This method was described in the literature as PRK, LASEK, or Surface Ablation Technique (SAT). To simplify the discussion we will use the broadly used term PRK for these procedure. Other variations of removing the epithelium by automated separator similar to MK (Epi-K, Epi-LASIK) or ablating the epithelium (transepithelial PRK, PTK) did not show a clear advantage over PRK are used rarely as standard SAT. This book evaluates the results of the currently modern refractive surgery techniques and does not present the older history. The older PRK result suffered from low safety because of stromal Haze and optical aberrations using an optical zones of 5 mm or less, and low efficacy because of common regression. The modern PRK uses large optical zones of typically 6.5 mm or larger and MMC to prevent haze and regression.