Marcus Gunn Pupil - Relative Afferent Pupillary Defect (RAPD)
Definition: Afferent loop of the pupillary light reflex is impaired (loss of sensory information)
Where: Optic nerve* (main cause), Retina, Macula
Main Association: Optic neuritis due to MS
How to test it?  Swinging flashlight test

Robert Marcus Gunn was a Scottish physician, that in 1902 described the "pathologic pupillary escape". Later (1959), Levitan better characterized this finding with the swinging light test

By Dr. Gabriela Figueiredo Pucci @gabifpucci @neudrawlogy

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