Hemianopia

Loss of half of the visual field in each eye. Hemianopia may be “homonymous” (in which the same side of both eyes is affected) or “heteronymous” (in which the loss is in opposite sides of the eyes). Visual loss may be temporary or permanent. Hemianopia is not due to a disorder of the eyes themselves but results from damage to the optic nerves or brain. Transient homonymous hemianopia in young people is usually caused by migraine. In older people, it occurs in transient ischaemic attacks. Permanent homonymous hemianopia is usually caused by a stroke, but it may result from brain damage by a tumour, injury, or infection. Hemianopia may also be caused by pressure on the optic nerve from a pituitary tumour.