Hemianopsia is the loss of half of the visual field. A person with hemianopsia only sees a portion of the visual field from each eye. Hemianopsia is classified by where the missing visual field is located:

  • Outer half of each visual field (bitemporal)
  • The same half of each visual field (homonymous)
  • Right half of each visual field (right homonymous)
  • Left half of each visual field (left homonymous)
  • Upper half of each visual field (superior)
  • Lower half of each visual field (inferior)

Vision loss can range from mild to severe. The likelihood that it will improve depends on the cause, the area of the brain affected, and/or how badly the optic nerves or other portions of the visual pathways were damaged.

Hemianopsia is caused by conditions that affect the brain or optic nerves.

The most common causes are:

Other less common causes that have been reported include:

  • Neurodegenerative disorders
  • Infections
  • Toxin exposures
  • Transient events, such as seizures or migraines

The Optic Nerve
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An injury or illness that puts pressure on the optic nerve can cause hemianopsia.
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