Corneal Sensitivity Testing Procedure for Ophthalmologic and Optometric Patients

Despite evidence of altered corneal sensitivity in a wide variety of ocular conditions, there is limited published guidance on corneal sensitivity testing and interpretation. This research establishes a protocol for corneal sensitivity testing that is simple, cost-effective, and easily implemented by eyecare providers across clinical settings. Ocular pain and dry eye disease can arise from multiple factors, including abnormal nerve function.

Precision based medicine requires diagnostic tests like corneal sensitivity to identify contributors. This test can detect decreased sensation, which suggests neurotrophic keratitis, or increased sensation, which suggests neuropathic neuroplastic pain as a contributor to symptoms. Quantitative methods for corneal sensitivity testing such as with aesthesiometers are infrequently used in clinical practice due to cost and challenges maintaining sterility.

While qualitative methods such as ours offer an inexpensive and accessible alternative, there is insufficient guidance on their implementation and interpretation. Our protocol is low cost, readily available and requires little training and time, meaning it could be performed by eyecare providers across clinical settings. Based on our experience, the results are consistent and the procedure can be easily incorporated into the existing workflow to support clinical diagnosis.

It will help pave the way for further research and further clinical studies to continue to advance the importance of corneal sensitivity testing in our patients. The more interest and the more research on corneal sensitivity will only enhance our understanding of the importance of this critical test for our patients. To begin, ask the patient with suspected ocular surface disease to sit in a comfortable position on a chair.

Remove contact lenses prior to corneal sensitivity testing and perform testing before administering any eye drops. Use a sterile cotton wisp or an unwaxed, unflavored dental floss as a stimulus for qualitative assessment of corneal sensitivity. Instruct the patient to fixate on a point or letter displayed on a test chart directly ahead.

Ask the patient to report when they feel the stimulus touch their cornea. Approach the patient's lateral side to reduce false positive responses caused by the patient reacting to the stimulus prior to contact. Gently bring the stimulus in contact with the center of the cornea and observe the blink reflex.

If the patient does not react to the stimulus and endorses not feeling the stimulus, put the score as absent or zero. When the patient reports a minor sensation in their eye, assign the score as reduced or one. When the patient blinks as soon as the stimulus touches the cornea or exhibits a mild reflex, report the score as normal or two.

When the patient exhibits a hypersensitive response and reports extreme discomfort or pain, assign the score as increased or three. To perform a thorough examination, test all quadrants of the cornea in clockwise order using a new stimulus. Next for testing the limbus, ask the patient to fixate on a target above the horizontal plane.

Repeat the corneal testing procedure in the contralateral eye using an unused cotton wisp, or dental floss. Finally, provide instructions for the follow-up examinations.