The most common cause of Marcus Gunn pupil is a lesion of the optic nerve (between the retina and the optic chiasm) due to glaucoma, or severe retinal disease, or due to multiple sclerosis. It is named after Scottish ophthalmologist Robert Marcus Gunn. A second common cause of Marcus Gunn pupil is a contralateral optic tract lesion, due to the different contributions of the intact nasal and temporal hemifields.
Relative afferent pupillary defect
Mechanical anisocoria
Physiological anisocoria
Persistent pupillary membrane
Ocular dysmetria
Nephroptosis
Scintillating scotoma
Optic disc pallor