Organization of the Regenerated Nerves in Human Corneal Grafts

PURPOSE: To examine by histopathology the degree of nerve regeneration in human corneal grafts and to determine the anatomic organization and morphology of the regenerated nerves. DESIGN: Experimental laboratory investigation. METHODS: Twelve corneal grafts from 12 patients (7 men and 5 women) aged 34-93 (mean, 66.9 years) were included. The most common indication for regrafting was late endothelial failure. The mean duration of graft survival was 6.41 years (range, 1-14 years). The freshly obtained specimens with a narrow rim of host tissue incorporating the graft-host junction were subjected to the acetylcholinesterase method for the demonstration of corneal nerves. RESULTS: Subbasal nerves were found in 75% and 25% of the grafts at the periphery and center, respectively. They were mostly originated from the host sub-basal nerves. Regenerated stromal nerves were detected in 83% of the specimens; half of them showed extension into the center of the graft. A lack of the normal link between the subbasal and stromal nerves was observed and almost all of the regenerated stromal nerves were found to remain within the stroma and did not contribute to the epithelial innervation. CONCLUSIONS: A persistent anatomic disorganization of the corneal nerves in human grafts was found even 14 years after surgery. This could explain the significant reduction of corneal sensation reported in previous studies. (Am J Ophthalmol 2012;153:29-37. (C) 2012 by Elsevier Inc. All rights reserved.)