The Swinging Flashlight Test in Acute Care: Appropriate Technique, Not Just Recognition, Determines Its Accuracy
The relative afferent pupillary defect (RAPD) is taught early in most medical careers. It is often tested in acute examinations, yet often the swinging flashlight test that elicits it can be very technique-dependent. In clinical settings where it can be most helpful, for example acute medical units, acute stroke units and emergency departments, it is frequently performed under conditions that work against it. Conditions like bright ambient light, a rushed single pass, and pupils examined once rather than swung repeatedly can affect the utility of this helpful neuro-ophthalmic test. This results in a sign that could either be missed, or worse falsely picked up as present when it is absent. RAPD clearly weighs very heavily on the differential for unilateral optic nerve or severe retinal pathology. Therefore, looking at the gap between how the test is taught and how it ends up being performed at the bedside can be very useful for clinicians.
