Tear film and ocular surface changes in a rabbit model of neurotrophic keratitis.

The authors studied the tear film and ocular surface in a rabbit model of neurotrophic keratitis to determine the extent to which the surface disease of neurotrophic keratitis resembled keratoconjunctivitis sicca. After denervation, tear film osmolarity increased and remained significantly elevated for 14 weeks. The ocular surface developed decreased conjunctival goblet cell density, decreased corneal epithelial glycogen, and morphologic changes similar to those seen in keratoconjunctivitis sicca. Although the conjunctival changes were consistent with the increases in tear film osmolarity and the surface disease of keratoconjunctivitis sicca, the corneal changes observed with denervation, including slit-lamp findings, morphologic changes, and decreases in glycogen, were too severe and rapid in onset to be accounted for by osmolarity alone. Neurotrophic "keratitis" is an ocular surface disease composed in part of the surface disease of keratoconjunctivitis sicca. However, the data also support an additional mechanism for corneal disease that could be due to the trophic influence of the trigeminal nerve.