How does corneal sensation testing play into your evaluation of a patient presenting with a chronic or recurrent epithelial defect of uncertain etiology?

Decreased corneal sensation may indicate the presence of neurotrophic keratitis (NK). The differential for NK is large but common causes are viruses such as HSV/VZV, DES, or diabetic keratopathy. Prior to topical anesthetic, I use a tissue folded to a point and touch the cornea at various locations ...