Health Library

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:

• Stroke
• Trauma
• Tumors

Other less common causes that have been reported include:

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

The Optic Nerve

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

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Having one of the above conditions puts you at risk for hemianopsia.

Tell your doctor if you have any of these, especially if you have a condition that can lead to hemianopsia:

• Sensation that something is wrong with your vision
• Bumping into objects
• Difficulty reading
• Difficulty driving (eg, changing lanes when there is an oncoming car or sideswiping objects)
• Visual hallucinations, such as lights or shapes

If you have any of these symptoms, do not assume it is due to hemianopsia. These symptoms may be caused by other conditions.

Your doctor will ask about your symptoms and medical history and do a physical exam. Your doctor may refer you to a neurologist, a doctor who treats brain conditions. You may also need to see an ophthalmologist, a doctor who specializes in eye care.

Tests may include:

• Visual field test—This is a test that makes a map of your field of vision. It is used to check whether there is damage to any area of vision. You will focus on a target in front of you and respond to lights that flash above, below, and to the right and left of the target.
• Magnetic resonance imaging (MRI) scan —This is a test that uses magnetic waves to make pictures of structures inside the brain. It will show if there is damage to your brain in an area that affects vision.

Talk with your doctor about the best treatment plan for you. Treatment focuses on treating the underlying condition and learning to live with your hemianopsia in daily life. Your hemianopsia may improve over time, depending on the cause. Treatment options include the following:

To help reduce your chances of getting hemianopsia, take steps to reduce your chances of having a condition that causes hemianopsia:

• Use caution in situations where a brain injury could occur (eg, wear helmets when appropriate, reduce falling hazards, etc.).
• If you are at risk for stroke, talk to your doctor about ways to decrease your risk.