Decreased corneal sensitivity is an important clinical parameter in neuro-ophthalmological evaluation. It may be associated with such disorders as diabetes, Herpes simplex keratitis, and myasthenia gravis, with corneal toxicity via chemical exposure or ocular drug therapy, and with ocular surgery. In this review, methods and precautions involved in measuring corneal sensitivity are summarized, and the clinical conditions in which corneal hypoesthesia may exist are discussed.