The swinging flashlight test is a simple, bedside test used to assess the relative afferent pupillary defect (RAPD) in the visual pathway. It’s a valuable tool for detecting unilateral or asymmetric optic nerve dysfunction or severe retinal disease.
How to Perform the Test
- Positioning: The patient sits in a comfortable position, and the examiner stands in front of them.
- Lighting: A bright flashlight is shone into one eye, then the other, in a swinging motion.
- Observation: The examiner observes the pupils’ reactions to the light stimulus.
What to Look For
- Normal response: Both pupils constrict equally when the light is shone into one eye and then the other.
- Relative afferent pupillary defect (RAPD): When the light is shone into the affected eye, the pupils may dilate or constrict less compared to when the light is shone into the healthy eye.
Clinical Significance
- Optic nerve damage: RAPD can indicate optic nerve damage or disease, such as optic neuritis or optic neuropathy.
- Retinal disease: Severe retinal disease can also cause RAPD.
- Neurological conditions: Certain neurological conditions, like stroke or multiple sclerosis, can affect the visual pathway and result in RAPD.
The swinging flashlight test is a useful screening tool for detecting visual pathway abnormalities and can guide further diagnostic testing and management.