Homonymous hemianopsia is a condition in which a person sees only one side ― right or left ― of the visual world of each eye. The condition results from a problem in brain function rather than a disorder of the eyes themselves.
Homonymous hemianopsia is a condition in which a person sees only one side ― right or left ― of the visual world of each eye. The person may not be aware that the vision loss is happening in both eyes, not just one.
Under normal circumstances, the left half of the brain processes visual information from both eyes about the right side of the world. The right side of the brain processes visual information from both eyes about the left side of the world.
In homonymous hemianopsia, an injury to the left part of the brain results in the loss of the right half of the visual world of each eye. An injury to the right part of the brain produces loss of the left side of the visual world of each eye.
This condition is created by a problem in brain function rather than a disorder of the eyes themselves.
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The most common cause of this type of vision loss is stroke. However, any disorder that affects the brain — including tumors, inflammation and injuries — can be a cause.
It is estimated that 70% of the injuries leading to hemianopsias are due to an obstruction (blockage) of the blood supply (stroke). Fifteen percent are due to tumors, and 5% are due to bleeding in the brain. Males from the ages of 50 to 70 are most frequently affected. This population is the group most likely to have diseases that affect the circulatory system.
As for the areas of the brain most affected, 40% of homonymous hemianopsias originate in the occipital (rear) lobe of the cerebral hemisphere. A total of 30% originate in the parietal (middle) lobe, 25% in the temporal (lower) lobe and 5% in the optic tract and lateral geniculate nucleus (pathways of the optic nerves connecting the eyes to the brain).
Note: There is no correlation between homonymous hemianopsia and nearsightedness or farsightnedness. These conditions are not related.
A thorough evaluation of the visual system is needed for an accurate diagnosis. The most common test is a visual field exam. The patient focuses on a target in front while noting lights flashed above, below, left and right of the target.
Magnetic resonance imaging (MRI) of the brain is used to diagnose the underlying location and cause of the brain injury.
Treatment by a low-vision specialist deals with two main areas: improving reading ability and navigating the environment.
Strategies to improve reading ability:
Strategies to improve navigating the environment:
There are no guaranteed measures that will prevent homonymous hemianopsia. However, following the same guidelines recommended to prevent stroke will help prevent the majority of cases.
Recovery from homonymous hemianopsia depends on what caused the condition and how badly the brain is injured.
Chances for a complete recovery are small if the cause is a stroke, particularly if the brain injury is severe. Any recovery that does occur is most likely to begin soon after the stroke, with virtually all improvement taking place within a 12- to 18-month period.
If the underlying cause isn't a stroke, the chances for recovery depend on the ability of treatment to correct the underlying condition, and on the specifics of each case.
Factors working against full recovery include advanced age of the patient, diabetes, high blood pressure and brain injuries that also cause impairment of language, thinking abilities or memory.
Last reviewed by a Cleveland Clinic medical professional on 04/26/2021.
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