Recovery of corneal innervation following photorefractive keratoablation
K. Tervo, T. M. Latvala and T. M. Tervo
Department of Anatomy, University of Helsinki, Finland.
OBJECTIVE: To study the morphological recovery of rabbit corneal nerves for
up to 12 months after photorefractive keratoablation. METHODS: 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. RESULTS:
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. CONCLUSIONS: 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.
