Histochemical evidence of limited reinnervation of human corneal grafts.

Acetylcholinesterase (AChE) positive nerve fibers were demonstrated histochemically in the normal human cornea and in 3 corneal grafts obtained after retransplantation. In the normal cornea AChE positive nerves form stromal nerve bundles, which divide into smaller branches contributing to the basal epithelial nerve plexus. Intraepithelial terminals are branches of this plexus. In a grafted cornea obtained 29 years after surgery the epithelium was innervated by a basal epithelial plexus, but only a few stromal nerve trunks had regenerated despite the long post-operative time. Corneal sensitivity had not returned to normal in this case. The remaining grafts, obtained less than 3 years after surgery, contained very few nerves. It seems that neither the architecture nor the density of corneal nerves fully regenerate in the graft cornea, and this probably explains why sensitivity does not return to normal.