Swinging Flashlight Sign
The swinging flashlight sign or test, originally described by Levitan in 1959, compares the direct and consensual pupillary light reflexes in one eye; the speed of swing is found by trial and error. Normally the responses are equal but in the presence of an afferent conduction defect an inequality is manifest as pupillary dilatation. The test is known to be unreliable in the presence of bilateral afferent defects of light conduction. Subjective appreciation of light intensity, or light brightness comparison, is a subjective version of this test.
Thompson HS, Corbett JJ. Swinging flashlight test. Neurology 1989;