Swinging-flashlight test

Process

Interpretation

• Normally, each illuminated pupil promptly becomes constricted. The opposite pupil also constricts consensually.
• When ocular disease, such as cataract, impairs vision, the pupils respond normally.
• When the optic nerve is damaged, the sensory stimulus sent to the midbrain is reduced. The pupil, responding less vigorously, dilates from its prior constricted state when the light is moved away from the unaffected eye and towards the affected eye. This response is a relative afferent pupillary defect.