Corneal Sensitivity Testing Procedure for Ophthalmologic and Optometric Patients

The cornea is the most densely innervated structure in the human body, making it one of the most sensitive tissues. Changes in corneal nerve sensitivity can be observed in several ocular surface diseases. Nerve sensitivity may be increased, as is often seen in patients with a neuropathic component to ocular pain, or decreased, as is seen in patients with neurotrophic keratitis. Corneal sensitivity testing involves assessing a patient's reaction to brief corneal stimulation, yields insight into the health of the corneal nerves, and provides diagnostic value for evaluating the health of the nerves and the interplay with the ocular surface. Currently, there is limited published guidance on how to conduct corneal sensitivity testing in a clinical setting. This article presents a protocol for testing corneal sensitivity using easy-to-use, low-cost materials that are readily accessible to eye care providers (either a cotton swab, a piece of dental floss, or a finely tapered tissue). This protocol allows for qualitative assessment of corneal sensitivity in which responses to corneal stimulation are rated from 0 (no response) to 3 (hypersensitive response). This test can be performed quickly (in approximately 30 s). Given its diagnostic value and accessibility, corneal sensitivity testing should be included as part of the standard eye examination for any patient undergoing an ocular surface examination.