Hemianopsia is when a person sees only half of the vertical visual field. It is typically caused by a stroke, brain injury, or lesion, not the eye itself.
A stroke is the most common cause of hemianopsia, causing 52 to 70% of hemianopsia cases.1,2 The prognosis of hemianopsia depends on the underlying cause of injury.
Long-term hemianopsia negatively affects quality of life. It reduces several abilities, including:
- Seeing the surrounding environment
This article discusses the causes of hemianopsia, how it affects vision, and frequently asked questions.
What is Hemianopsia?
Hemianopsia is also called hemianopia. It’s a vision loss on one-half of the left or right side of the visual field. It usually occurs in both eyes.
Hemianopsia is a disruption to the optic tract along the visual pathway. The visual pathway spans from the retina (the light-sensitive layer at the back of the eye that delivers signals to the optic nerve) to the primary visual cortex in the occipital lobe (visual processing part of the brain).
While a stroke is the most common cause of homonymous hemianopsia, other factors can also disrupt your visual field, including:
- Head trauma
- Surgical procedure
- Multiple sclerosis
- Alzheimer’s disease
- Epilepsy (seizures)
Hemianopia vs. Hemianopsia
Hemianopia and hemianopsia are the same. They both mean the loss of half your field of vision due to a brain injury.
How Does Hemianopsia Impact Vision?
The location of the lesion on the visual pathway determines the impact of vision loss. These locations are classified as prechiasmal, optic chiasm, or retrochiasmal.
The optic chiasm is the part of the visual pathway where the optic nerves from each eye cross each other and continue to the brain.
That means that the left optic nerve communicates with the right side of the brain, while the right optic nerve communicates with the left side of the brain.
- Prechiasmal lesions. Impacts the optic nerve, causing monocular blindness in the affected eye (visual disturbance or loss in one eye for a period)
- Chiasmal lesions. Impacts the optic chiasm, causing bitemporal hemianopsia (inability to see from the outer half of each eye’s visual field)
- Retrochiasmal lesions. Impacts the optic tract or primary visual cortex, causing homonymous hemianopsia (seeing only half of each eye’s visual field)
What are the Symptoms of Hemianopsia?
The symptoms of hemianopsia include:
- Bumping into objects
- Missing parts of words while reading
- Double vision
- Inability to see the entire object in front of you
- Drifting while you walk
- Visual hallucinations of light or shapes
- Decreased night vision
- Difficulty with driving (drifting in the lane, unstable steering, etc.)
Different Types of Hemianopsia
There are several types of hemianopia, depending on where the brain injury is located and how much of the vision field is affected.
These different types include:
Homonymous hemianopsia is the loss of half of vision on the same side of the visual field. It is caused by a brain injury located post-chiasmal on the optic tract closest to the brain.
If the brain injury were on the left side, half the vision in the right eye would be lost. If the brain injury were on the right side, half the vision in the right eye would be lost.
Heteronymous hemianopsia is the loss of vision on the opposite side of each eye. This type of hemianopsia can either be bitemporal or bi-nasal.
It’s typically caused by compression of the optic chiasm from a pituitary gland tumor. An abnormal growth or lesion on the pituitary gland may also cause hormonal changes.
- Bitemporal hemianopsia. Your peripheral vision is blacked out in the outer half of your visual fields.
- Bi-nasal Hemianopsia. Vision loss in the inner part of the eye (closest to the nasal)
Superior hemianopsia is the loss of the upper half of your visual fields. This occurs when the optic radiations (part of the visual pathway) are damaged in the brain's temporal lobe.
Inferior hemianopsia is the loss of the lower half of your field of vision. This can occur if a tumor or lesion pushes down the optic tract's upper part.
Quadrantanopia hemianopia is the bilateral loss of vision in one quadrant or one-fourth of your field of vision. It can occur due to lesions in the occipital lobe.
Causes of Hemianopsia and Bitemporal Hemianopsia
While a stroke is the most common cause of homonymous hemianopsia, other factors can also disrupt your visual field.
These factors include:
A traumatic brain injury (TBI) is the cause of about 10% of hemianopsia cases. About 90% of people with a TBI suffer visual deficits.5,6
There are many causes of brain injuries, including:
- Cerebral palsy
- Blow to the head
- Gunshot wound
- Motor vehicle accidents
- Contact sports
- Brain bleed
Tumor and Lesions
Intracranial tumors and lesions on the optical tract are leading causes of hemianopsia. The condition can also occur if tumors or lesions are in other structures.
These structures include:
- Lateral geniculate nucleus (structure that receives visual input from both eyes)
- Optic radiation
- Visual cortex
Common neurological conditions that cause hemianopia include:
- Alzheimer's disease
- Multiple sclerosis
- Neurosyphilis (brain infection)
- Vascular malformations (abnormal formation of blood vessels)
- Neurological surgery
People who have had a stroke, brain tumor, or brain injury have the highest risk of developing hemianopsia and other visual field deficits.
All types of hemianopsia are diagnosed with scans and tests to find the underlying cause. A visual field test can confirm what part of your vision is blocked.
Subsequent tests and scans will help determine what part of the visual pathway is affected. These tests and scans may include:
- A complete evaluation of the visual system
- Cranial nerve assessment
- Physical exam
- Neurological exam
- MRI scan
- Blood tests
Can People Recover from Hemianopsia?
While there is no cure for hemianopsia, the potential for vision rehabilitation will depend on the underlying cause.
For hemianopia caused by a stroke, the outlook will depend on the time between the stroke event and diagnosis of hemianopsia and the severity of brain injury. If vision does improve, it typically happens between 3-6 months following a stroke.7
For people with bitemporal hemianopsia due to a pituitary gland tumor, 75-95% will see vision improvement after removing the tumor.1
How is Hemianopsia Treated?
After addressing the underlying cause of hemianopsia, doctors have a couple of rehabilitation strategies that can help improve vision loss, including:
- Visual restoration training to improve visual information processing
- Visual assistive devices such as prism lenses to help with double vision
- Saccadic visual search training to improve the efficacy of eye movements
Impact of Hemianopsia On Daily Life
Hemianopsia greatly impacts the quality of life and activities of daily living, especially driving and reading.
The significant impacts on everyday life may include:
- Higher risk of trips and falls
- Anxiety and depression
- Ability to move about independently
- Visual hallucinations or seeing objects that aren’t there
Some people with hemianopia may not be aware that they have lost half of their field of vision. People with visual inattention, also called visual neglect, may ignore everything on one side of them.
Common Questions about Hemianopsia
Does stroke cause hemianopsia?
Yes. A stroke is the leading cause of hemianopsia. Other causes include brain injuries and tumors.
What are the names of hemianopsia?
Hemianopsia is also referred to as hemianopia or homonymous hemianopia.
What is an example of a complete hemianopsia?
Complete hemianopia is when you lose one-half of your field of vision. For example, a doctor doing a vision field test will place a finger in each quadrant of your field of vision.
If you miss one quadrant, you have partial hemianopia. If you miss two quadrants, you have complete hemianopia because you are missing 50% of your field of vision.
Hemianopsia is the loss of half of your field of vision. It is caused by a stroke, brain injury, or brain tumor. Hemianopsia dramatically impacts the quality of life, making driving, reading, and moving around your environment difficult.
Treatment and outcome for hemianopsia depend on the underlying cause. While there is no cure for hemianopsia, some might see vision improvement after tumor removal or vision rehabilitation training.
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