Hemianopia is loss of half of the visual field in each eye, usually on the same side, due to damage along the visual pathways in the brain. The eyes themselves can be healthy, but part of what the person should see is missing.
Causes and Patterns
The most common cause of hemianopia is stroke affecting the occipital lobes or optic radiations, but it can also follow head injury, brain tumour, or other neurological disease. The defect often respects the vertical midline, with right or left halves of the field affected.
- Homonymous hemianopia affects the same side of the field in both eyes
- Quadrantanopia involves loss of a quarter of the visual field
- Defects are demonstrated on formal visual field testing
- Other neurological signs may coexist, depending on the lesion site
Impact and Adaptation
Hemianopia can interfere with reading, mobility, and driving because obstacles or text on one side may be missed. Rehabilitation focuses on compensatory strategies such as scanning training, visual cues, and, in selected cases, optical aids to expand awareness of the missing side.
- People may bump into objects or miss steps on the affected side
- Reading can be slowed if the field loss is on the side used to scan ahead
- Occupational therapy and low vision services support daily activities
- Regular neurological and ophthalmic follow-up helps monitor stability
