What is hemianopsia
Overview: Hemianopsia is a loss of vision in half of your visual field of one eye or both eyes. Common causes are:
- brain tumor
- trauma to the brain
Normally, the left half of your brain receives visual information from the right side of both eyes, and vice versa.
Some information from your optic nerves crosses to the other half of the brain using an X-shaped structure called the optic chiasm. When any part of this system is damaged, the result can be a partial or complete loss of vision in the visual field.
What causes hemianopsia?
Hemianopsia can occur when there’s damage to the:
- optic nerves
- optic chiasm
- visual processing regions of the brain
The most common causes of brain damage that can result in hemianopsia are:
- traumatic head injuries
Less commonly, brain damage can also be caused by:
- exposure to toxins
- transient events, such as seizures or migraines
Types of hemianopsia
With hemianopsia, you can see only part of the visual field for each eye. Hemianopsia is classified by the part of your visual field that’s missing:
bitemporal: outer half of each visual field
homonymous: the same half of each visual field
right homonymous: right half of each visual field
left homonymous: left half of each visual field
superior: upper half of each visual field
inferior: lower half of each visual field