Walsh & Hoyt: Tests of Corneal Sensation

Assessment of response to corneal pain stimulation is made by both subjective report and objective observation. The patients report of differences in sensation after equal stimulation of the two corneas may indicate unilateral reduction in ophthalmic division sensory function; however, only the alert, relatively intelligent, and comfortable patient can contribute this information reliably. More often, the examiner must rely upon objective signs, such as involuntary blink reflex and head withdrawal. These are of particular value in examination of the obtunded or semicomatose individual. Both depth of coma and difference in corneal sensitivity can be assessed by the patients involuntary response to corneal stimulation. It should be noted that long-time contact wearers may have a substantial reduction in response to corneal stimulation, but this should be symmetric