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Hemianopsia

Definition

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.

Causes

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
IMAGE
An injury or illness that puts pressure on the optic nerve can cause hemianopsia.
Copyright © Nucleus Medical Media, Inc.

Risk Factors

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

Symptoms

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.

Diagnosis

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.

Treatment

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:

Visual Aids

These may be used to help increase your visual field. They must be fitted by an eye care professional. Prisms may be attached to glasses. A prism is a clear plastic sheet that fits the lenses of your glasses. You may have a permanent prism mounted into the lens. It shifts the location of an image so that it is within your field of vision. You will be trained on how to use the prism to make up for your visual field defect. Mirrors or inverted telescopes can also be used to increase your visual field.

Reading Strategies

You may be taught strategies that will make reading easier. Reading can be difficult if you have hemianopsia because you may have trouble finding the beginning or end of a word or line of text.

You may want to use a ruler or sticky note to mark the beginning or end of the text. For example, if you have right homonymous hemianopsia, use a sticky note to mark the end of a line of text. You will know that you have not reached the end of the line until you see the sticky note.

Some people with hemianopsia benefit from turning a text and reading it vertically (up and down), rather than horizontally (side to side).

Lifestyle Changes

Other changes can help you deal with hemianopsia in daily life:

  • Make frequent head turns a habit. This will help you capture things outside your field of vision.
  • When walking with others, place them on the affected side. For example, if you have a left homonymous hemianopsia, they should stay on your left side. This will prevent you from bumping into objects outside of your field of vision.
  • In a theater, sit toward the affected side (eg, on the right if you have right homonymous hemianopsia). That way, more of the action will be within your field of vision.
  • Talk to your doctor about whether you can drive. Some rehabilitation centers have driving simulators that measure your ability to drive safely.

Prevention

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.

Revision Information

  • Reviewer: Rimas Lukas, MD
  • Review Date: 06/2011 -
  • Update Date: 06/24/2011 -
  • American Academy of Ophthalmology

    http://www.aao.org/

  • Lighthouse International

    http://www.lighthouse.org/

  • Canadian Ophthalmological Society

    http://www.eyesite.ca/

  • Canadian Stroke Network

    http://www.canadianstrokenetwork.ca/

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