What is Hemianopsia?
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Hemianopsia is a visual field defect involving loss of vision in half of the visual field in one or both eyes. It is most commonly caused by lesions along the retrochiasmal visual pathway.
Types of hemianopsia
- Homonymous hemianopsia – loss of the same side of the visual field in both eyes; typically due to stroke affecting the occipital lobe or optic radiation.
- Bitemporal hemianopsia – loss of the temporal visual fields; often caused by optic chiasm compression, classically from a pituitary adenoma.
- Binasal hemianopsia – rare; may result from bilateral perichiasmal lesions.
Clinical features
Patients may present with:
- Difficulty reading or bumping into objects
- Visual hallucinations (in some cases)
- Often unaware of the deficit (visual neglect, particularly with right parietal lesions)
Common causes
- Stroke – particularly posterior cerebral artery territory infarcts
- Tumours – pituitary adenoma, meningioma, glioma
- Trauma
- Multiple sclerosis
- Post-surgical or post-radiation effects
Assessment
- History and examination – assess for neurological signs and underlying risk factors (e.g. AF, hypertension)
- Visual field testing – confrontation or formal perimetry
- Neuroimaging – urgent MRI brain (or CT if stroke suspected) to localise lesion
Management
- Treat underlying cause – e.g. anticoagulation in stroke, referral to endocrinology for pituitary mass
- Referral – neurology or ophthalmology, depending on suspected aetiology
- Support – visual rehabilitation services, occupational therapy, driving advice (DVLA guidance)