A 52 year old female complains of sudden visual abnormalities. Her history reveals a 30 pack-year history of smoking, hypeension, and hypercholesterolemia. A head CT shows a lesion in the right occipital lobe and an angiogram reveals an embolic stroke of the right posterior cerebral aery. What type of visual deficit is she most likely experiencing?

The posterior cerebral aeries supply the coical surfaces of the occipital and medial temporal lobes. Damage to one occipital lobe (e.g., by trauma or by ischemia/infarction due to stroke) usually produces a contralateral homonymous hemianopia. Occlusion of the right posterior cerebral aery would therefore result in a left homonymous hemianopia;blindness in the left half of the visual field in both eyes. In addition, involvement of the medial temporal lobe might give rise to peduncular hallucinosis;visual illusions or elementary (unformed) hallucinations. Bilateral lesions would cause "coical" blindness, which does not affect the pupillary reflexes. Bitemporal hemianopia is a loss of vision in the temporal quadrants of the visual field. (It is also termed heteronymous hemianopia). This occurs in lesions of the optic chiasm, which may occur with pituitary tumors. Central scotoma is a loss of vision in the center of the visual field, with preservation of the peripheral fields. It is associated with optic neuritis, a common complication of multiple sclerosis. Superior quadrantanopia is caused by lesions in the upper poion of the contralateral temporal lobe. Ref: Ropper A.H., Samuels M.A. (2009). Chapter 13. Disturbances of Vision. In A.H. Ropper, M.A. Samuels (Eds), Adams and Victor's Principles of Neurology, 9e.