Swinging Flashlight Test

How to Perform

In a dimly lit room, have the patient fixate on a distant target. Shine a bright light into one eye for two to three seconds and note the pupillary constriction, then swing the light rapidly across the bridge of the nose to the other eye and observe its response, alternating back and forth every few seconds. Normally each pupil holds its constriction as the light arrives; the abnormal response is for the illuminated pupil to dilate as the light swings onto it rather than holding constriction.

How to Interpret