Mouse study: How dry eye might alter corneal nerves
Invest Ophthalmol Vis Sci. 2018 Apr 1;59(5):1986-1995. doi: 10.1167/iovs.17-23743.
Alterations of Murine Subbasal Corneal Nerves After Environmental Dry Eye Stress.
Simsek C1, Kojima T1, Dogru M1, Tsubota K1.
To investigate the morphologic changes in the corneal subbasal nerve (CSN) plexus in wild-type mice after exposure to environmental dry eye stress (EDES) using in vivo confocal microscopy (IVCM).
We examined 22 eyes of 8-week-old wild-type male mice (Balb/c, n = 11). The mice were exposed to an air fan inside a small compartment 5 hours/day for 3 days (EDES). Aqueous tear secretion and corneal epithelial damage were assessed. The CSNs were investigated by laser-scanning IVCM. Density; tortuosity; and reflectivity of CSNs; and dendritic cell (DC) densities were evaluated using semi-automated NeuronJ software.
EDES significantly decreased the aqueous tear secretion quantity (P = 0.0019) and significantly increased the corneal fluorescein (P = 0.005) and lissamine green staining scores (P = 0003). The CSN density showed a significant decrease after EDES exposure (before, 2813 ± 762 pixels/frame; after, 1906 ± 896 pixels/frame, P = 0.0071). The tortuosity and the reflectivity grades did not show statistically significant differences after EDES exposure (tortuosity, P = 0.307; reflectivity, P = 0.758). However, the mean DC density showed a significant increase after EDES exposure (before, 12.62 ± 5.94 cells/mm2; after, 15.93 ± 5.30 cells/mm2, P = 0.026).
Even short-term exposure to EDES induced alterations in the CSN plexus morphology including decreased subbasal corneal nerve density and increased amount of DCs in mice. The EDES mouse model is a promising model to study the ocular surface and corneal nerve changes associated with dry eye disease.