Recovery of corneal innervation following photorefractive keratoablation.

Abstract

To study the morphological recovery of rabbit corneal nerves for up to 12 months after photorefractive keratoablation. The histochemical acetylcholinesterase reaction was used to demonstrate morphological features in rabbit corneal nerves at 1 hour, at 6 weeks, and at 3, 6, or 12 months after photorefractive keratoablation. Photorefractive keratoablation ablated the subepithelial nerve plexus, leaving sharply cut stromal nerves. Epithelial innervation was almost completely restored in 3 months, with innervation proceeding from the epithelial nerve plexuses at the wound margins, but the stromal nerves showed abnormal morphological features throughout the study. Abnormally coiled, regenerating axons emerged from the cut stromal nerves. The first of them were observed to penetrate into the epithelium 3 months postoperatively. The acetylcholinesterase reaction of the epithelial cell membranes was weaker in the wound area, except in the specimens that were observed at 12 months. Epithelial innervation was restored relatively quickly; otherwise, neural recovery was slow. The structure and architecture of the stromal nerves was abnormal even in the the specimens that were observed at 12 months. We hypothesize that corneal nerve damage induced by deep photoablations may correlate with the predictability problems and haze.