Moreover, VEGF-B improved corneal sensation and epithelial regeneration, accompanied with the elevated corneal content of PEDF, but not NGF, CNTF, GDNF or substance P. Taken together, hyperglycemia-suppressed endogenous VEGF-B expression in corneal epithelium contributes to the diabetic corneal neuropathy, while exogenous VEGF-B promoted the recovery of corneal innervations and trophic functions in diabetic mice, suggesting VEGF-B may be used as a therapeutic target for diabetic keratopathy. This evidence concerns the gene GDNF and Hyperglycemia.