Hemianopic

Hemianopic is an adjective relating to hemianopia, a defect of the visual field in which half of the field of view is missing in one or both eyes. The most common presentation is homonymous hemianopia, where the same half of the visual field is lost in both eyes (for example, the left half of the field in each eye). In many cases, the central or macular region is relatively spared, a phenomenon known as macular sparing that reflects the organization of the visual cortex and its blood supply.

Causes of a hemianopic field loss are typically neurological and arise from damage after the optic chiasm. The most frequent etiologies are stroke or other vascular events affecting the posterior cerebral artery territory, followed by tumors, traumatic brain injury, and demyelinating diseases. Less commonly, seizures, infections, or surgical complications can contribute. The pattern of loss depends on the location of the lesion along the visual pathways, with postchiasmal lesions producing congruent field defects.

Diagnosis relies on formal visual field testing, such as perimetry, along with imaging to identify structural causes. Perimetry assesses the extent and pattern of field loss, while MRI or CT helps localize the lesion.

Management focuses on treating the underlying cause where possible and addressing functional impact. Strategies may include vision rehabilitation, compensatory scanning training, safety modifications, and, in selected cases, visual field augmentation with prisms. Prognosis varies with cause and extent of brain injury; some patients experience stabilization or gradual improvement, while others have persistent deficits.