"Robert Marcus Gunn (1850-1909) was a Scottish ophthalmologist 2."
"An RAPD is classically elicited on the swinging light test (Marcus Gunn test) 5. If light is shone into the normal eye, both pupils constrict normally and equally 5. However, in response to light input to the affected eye, both pupils do not constrict to a normal extent, and may be seen to paradoxically dilate as the light moves quickly over it 5. There is typically, but not always, associated visual loss 5."