Homonymous hemianopsia
| Homonymous hemianopsia | |
|---|---|
 |
|
| Paris as seen with left homonymous hemianopsia | |
| Classification and external resources | |
| Specialty | ophthalmology |
| ICD-10 | H53.4 |
| ICD-9-CM | 368.46 |
Hemianopsia or hemianopia is visual field loss on the left or right side of the vertical midline. It can affect one eye but usually affects both eyes. Homonymous hemianopsia, or homonymous hemianopia, is hemianopic visual field loss on the same side of both eyes. Homonymous hemianopsia occurs because the right half of the brain has visual pathways for the left hemifield of both eyes, and the left half of the brain has visual pathways for the right hemifield of both eyes. When one of these pathways is damaged, the corresponding visual field is lost.
Mobility can be difficult for people with homonymous hemianopsia. “Patients frequently complain of bumping into obstacles on the side of the field loss, thereby bruising their arms and legs.”3
People with homonymous hemianopsia often experience discomfort in crowds. “A patient with this condition may be unaware of what he or she cannot see and frequently bumps into walls, trips over objects or walks into people on the side where the visual field is missing.”5
A related phenomenon is Hemispatial neglect, the possible neglect of the right or left. The patient is not conscious of its existence. The right side of the face is not shaven, make up is applied to one side of the face only and only half of a plate of food is eaten. This, however, is not necessarily due to a sensory abnormality, and is therefore distinct from hemianopsia.
Homonymous hemianopsia can be congenital, but is usually caused by brain injury such as from stroke, trauma, tumors, infection, or following surgery.
Vascular and neoplastic (malignant or benign tumours) lesions from the optic tract, to visual cortex can cause a contralateral homonymous hemianopsia. Injury to the right side of the brain will affect the left visual fields of each eye. The more posterior the cerebral lesion, the more symmetric (congruous) the homonymous hemianopsia will be. For example, a person who has a lesion of the right optic tract will no longer see objects on his left side. Similarly, a person who has a stroke to the right occipital lobe will have the same visual field defect, usually more congruent between the two eyes, and there may be macular sparing. A stroke on the right side of the brain (especially parietal lobe), in addition to producing a homonymous hemianopsia, may also lead to the syndrome of hemispatial neglect.
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