Hemianopia: Partial Vision Loss After Brain Injury
This article explains the different types of hemianopia, their associated symptoms, some possible causes, and the treatment options available.
Clinicians classify the type of hemianopia a person has by their visual field.
Homonymous hemianopia occurs when the same side of the visual field is affected in both eyes. If you cannot see the left side of your visual field in both eyes, you have homonymous hemianopia.
Heteronymous hemianopia occurs when different sides of the visual field are affected. For instance, you may not be able to see the left side of your visual field in your left eye or the right side of your visual field in your right eye. There are two types of heteronymous hemianopia.
- Binasal hemianopia: Loss of vision occurs in the visual field closest to the nasal passages. Unlike other types of hemianopia, binasal hemianopia typically occurs due to ocular conditions, such as damage to the retinal nerve fibers or glaucoma.
- Bitemporal hemianopia: Loss of vision occurs in the visual field closest to the temples. Damage to the optic chiasm, which is where the optic nerves from each eye cross each other, is the typical cause of bitemporal hemianopia.
Instead of left or right, loss of vision occurs in one quadrant of the visual field. Typically, the location of the brain damage determines the pattern. This could be either partial or complete hemianopia. There are two types of quadrantanopia.
- Superior hemianopia: The loss of vision occurs in the upper visual field in either or both eyes.
- Inferior hemianopia: The loss of vision occurs in the lower visual field in either or both eyes.
The symptoms of hemianopia may occur immediately following a stroke, a brain injury, or an invasive surgery. Sometimes, symptoms occur with time as the result of progressive neurological conditions, such as multiple sclerosis (MS), epilepsy, or Alzheimer’s disease.
People with hemianopia may also experience disorientation or double vision. In turn, changes in vision and visual field can lead to both physical and mental difficulties, which may include:
- bumping into objects
- having difficulty crossing the street
- having difficulty reading and comprehending written text
- having difficulty driving
- missing hazards that other people point out
- not participating in or enjoying leisure activities as before
- experiencing a lower mood than usual
When to contact a doctor
Contact a doctor for an evaluation if you or someone you care for experiences vision or visual field problems that do not resolve quickly. Always seek medical care for head injuries, especially when there are changes in your vision or visual field.
Call 911 for any symptoms of a stroke. These include face drooping, arm weakness, and speech difficulties.
Stroke is the most common cause of homonymous hemianopia. Other causes of hemianopia include:
- Alzheimer’s disease
- brain aneurysm
- neurosurgical procedures
- a traumatic brain injury
- tumors and lesions
To diagnose hemianopia, your doctor will start by taking a medical history and performing a physical exam, including a vision test and a neurological assessment. They likely will order the following imaging tests as well:
The results of these tests may help pinpoint the neurological problem causing the vision loss. It may take some time to determine the exact cause of hemianopia and how to treat it.
Treating the underlying cause of hemianopia, such as a brain tumor, may help increase the visual field.
There are many treatment and management options available to help people with hemianopia. These include:
- Vision training: These exercises train your eye muscles to move in a coordinated fashion, which improves vision.
- Low vision rehabilitation: These techniques help you perform daily activities using your remaining vision.
- Occupational therapy: This helps improve eye alignment, visual processing, and eye tracking. It also teaches you how to effectively use your remaining vision.
- Vision restoration therapy: This Food and Drug Administration (FDA)-cleared therapy involves using a computer to increase visual function. It trains the brain to process things that you normally would not see — due to hemianopia — into the area that you can see.
- Prism therapy: This therapy uses prisms to expand the existing visual field.
The outlook for people with hemianopia depends on the type of hemianopia they have and their other underlying medical conditions.
For homonymous hemianopia due to stroke, studies from 2013 and 2014 found that only 17–18% of people regained their full vision within 28–30 days of the stroke, according to a 2021 article. For bitemporal hemianopia due to pituitary tumors, 79–95% of people experienced a positive effect after tumor removal.
In general, the sooner you start vision therapy following the onset of vision loss, the higher the likelihood of positive changes. In a 2020 study led by developers of an internet-based eye movement intervention, less time between injury or stroke and the start of eye training correlated with higher scores on performance measures.
For some people with hemianopia, adjusting to the condition may not take long. For instance, people with superior quadrantanopia typically have to make minimal adjustments to their daily routine to compensate for the partial loss of vision.
People with more severe hemianopia often need additional support to maintain their quality of life. This includes accepting physical support, such as having someone to drive you places or walk with you. It also includes receiving mental support, such as talking with a therapist to deal with the feelings that can accompany a loss of vision, independence, or both.
Hemianopia is the partial loss of vision due to a stroke, a brain injury, or a neurological condition, such as MS. Sometimes, vision loss resolves on its own, but it may require treatment, such as vision training and occupational therapy. Depending on the cause, full restoration of the impaired vision field is unlikely to occur.