How to Diagnose Optic Neuropathy in a Blink!

In response to a light stimulus, a reflex orbicularis contraction of the upper and lower eyelid occurs. Our purpose was to determine if the photic blink reflex can be used as an objective clinical measure of afferent visual pathology, in a similar manner to Relative Afferent Pupillary Defect (RAPD). We compared the orbicularis and pupillary responses to increasing light in subjects with and without unilateral optic neuropathy. We hypothesized that the orbicularis contraction correlates with pupil contraction for the same light stimulus and would produce a relative afferent eyelid defect (RAED) in optic neuropathy.