Hemianopia

Loss of half the visual field

Overview

Hemianopia is the loss of vision in half of the visual field. Because the optic pathways cross at the optic chiasm, damage behind the chiasm on one side of the brain, commonly from stroke, tumor, or trauma, causes homonymous hemianopia, loss of the same side of the field in both eyes. Damage at the chiasm itself, typically from a pituitary tumor, causes bitemporal hemianopia, loss of the outer halves of both fields. People may bump into objects on the affected side, lose their place when reading, and face restrictions on driving. Visual field testing maps the defect, and rehabilitation focuses on compensatory scanning strategies.