Reflex Upper and Lower Eyelid Movement in Response to Light Stimuli

In response to a light stimulus, a reflex orbicularis contraction of the upper and lower eyelid occurs in proportion to light intensity. Our purpose was to determine if the photic blink reflex can be used as an objective, clinical measure. To initiate our understanding of this underutilized reflex, we compared the photic eyelid reflex to the pupil light reflex in the same eyes across subjects. We hypothesized that the percent change in fissure narrowing will correlate with the percent change in pupil contraction for the same light stimulus. We also hypothesized that oculosympathetic deficits to Mueller's muscle and the iris dilator muscle would result in deficits in reflex widening of the palpebral fissure correlating to reflex dilation of the pupil.