Many diseases can affect corneal nerves. Corneas that lack normal sensation are considered neurotrophic. Neurotrophic corneas are predisposed to persistent epithelial defects, recurrent erosions, and corneal ulcers. These can lead to a variety of complications, from subjective pain, discomfort, and blurry vision, to corneal perforation and endophthalmitis. Neurotrophic corneas and the persistent epithelial defects associated with them can be very difficult to treat. Non-invasive measures include topical drops (artificial tears, antibiotics, or steroids), bandage contact lens, and punctal plugs. More invasive surgical treatments include membrane grafts, tarsorrhaphy, and keratoplasty. Despite these treatments, many neurotrophic corneas still do not heal. This study aims to test the efficacy of topical insulin in the treatment of neurotrophic keratopathy.