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 be mild to severe.
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:
Transient events, such as seizures or
- Toxin exposures
- Neurodegenerative disorders
- Nonketotic hyperglycemia
The Optic Nerve
An injury or illness that puts pressure on the optic nerve can cause hemianopsia.
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Having a condition that affects the brain or optic nerves puts you at risk for hemianopsia.
Vision problems are the main symptom and may include:
- Bumping into objects
- Difficulty reading
- Difficulty driving, such as changing lanes when there is an oncoming car or sideswiping objects
- Seeing lights or shapes that are not there
You will be asked about your symptoms and medical history. A physical exam will be done. 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.
Your field of vision will be tested. This can be done with a visual field test that makes a map of your field of vision.
Images may be taken of structures inside your brain. This can be done with an MRI.
Talk with your doctor about the best treatment plan for you. If an underlying condition is found, treatment will be based on that illness.
Your hemianopsia may improve over time, depending on the cause. The likelihood that it will improve depends on the cause, the area of the brain affected, and how badly the optic nerves or other portions of the visual pathways were damaged. Treatment options include the following:
Aids 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 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 be taught strategies that will make reading easier.
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).
Other changes can help you deal with hemianopsia in daily life:
- Make frequent head turns and eye movements 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. 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.
Hemianopsia is often caused by trauma or stroke. Use caution in situations where a brain injury could occur by wearing a helmet and avoiding fall hazards. Talk to your doctor about ways to decrease your risk of stroke.
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Last reviewed November 2017 by EBSCO Medical Review Board
Rimas Lukas, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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