Marcus Gunn pupil or relative afferent pupillary defect (RAPD) is a medical sign observed during the swinging-flashlight test whereupon the patient's pupils constrict less (therefore appearing to dilate) when a bright light is swung from the unaffected eye to the affected eye. The affected eye still senses the light and produces pupillary sphincter constriction to some degree, albeit reduced.
The most common cause of Marcus Gunn pupil is a lesion of the optic nerve (between the retina and the optic chiasm) or severe retinal disease. It is named after Scottish ophthalmologist Robert Marcus Gunn.
Read more about Marcus Gunn Pupil: Examination
Famous quotes containing the words gunn and/or pupil:
“Direct me gods, whose changes are all holy,
To where it flickers deep in grass, the moly:”
—Thom Gunn (b. 1929)
“All claims of education notwithstanding, the pupil will accept only that which his mind craves.”
—Emma Goldman (1869–1940)