The relationship between subbasal nerve morphology and corneal sensation in ocular surface disease.

PURPOSE: The purpose of this study was to evaluate the relationship between the in vivo confocal microscopic (IVCM) morphology of subbasal corneal nerves and corneal sensitivity in patients with ocular surface disease.
METHODS: Ten healthy volunteers (control group), 12 patients with dry eye (dry-eye group), and 14 patients treated with IOP-lowering topical medications (glaucoma group) were included. Central corneal sensation was measured using the contact Cochet-Bonnet esthesiometer. IVCM of the cornea was performed and the following subbasal corneal nerves parameters were analyzed: density, number, width, number of beadings, number of branching, tortuosity, and reflectivity. One eye of each subject was included in the study.
RESULTS: Corneal sensitivity was significantly decreased in dry-eye and glaucoma patients compared with controls. The density and number of subbasal corneal nerves were also significantly decreased in dry eye and glaucoma patients compared with controls. There was no difference in terms of subbasal nerve width, number of beadings, tortuosity, reflectivity, and number of branching between the dry-eye, the glaucoma, and the control groups. In all subjects, corneal sensitivity correlated positively with the density and number of subbasal nerves; however, in the dry-eye group, corneal sensitivity correlated with the density and the number of nerves, whereas in the glaucoma group, corneal sensitivity correlated only with the tortuosity of subbasal nerves.
CONCLUSIONS: The relationship between corneal sensation and subbasal nerve morphology, as evaluated with IVCM, depends on the pathophysiological mechanism of ocular surface disease.