Wound healing and myopic regression following photorefractive keratectomy

Scrapings from the treated area of 17 patients who had undergone photorefractive keratectomy were analyzed. All patients had regressed to myopia and were scraped at the time of retreatment. Three scrapings from the epithelium of patients undergoing primary photorefractive keratectomy served as control. Formalin fixed and paraffin embedded, the specimens were sectioned and stained specifically for hyaluronic acid. Hematoxylin was used for counterstaining in all specimens. Scrapings revealed either epithelial hyperplasia (11 cases) or an increased amount of extracellular material (15 cases) or both (9 cases). Five of the specimens stained positive for hyaluronic acid. Four of these cases showed the highest degree of corneal haze. The latter suggests a role for hyaluronic acid formation in excessive wound healing, causing myopic regression. All patients had received prolonged topical steroid treatment, a measure that may suppress a normal occurrence of hyaluronic acid.