What is Hemianopia?
Complete hemianopia, also called hemianopsia, is the loss of vision in half your vertical visual field in one or both eyes. It is caused by an event such as a stroke, brain injury, or lesion that disrupts the visual pathway between the eyes and brain.
There are different types of hemianopia, including homonymous hemianopia and heteronymous hemianopia. Each type is classified by what part of the visual field is affected.
Because hemianopia stems from an event or complication, hemianopia is considered a brain condition, not an eye condition.
Types of Hemianopia
The visual pathway is part of the central nervous system (CNS). It is made up of several vital neurons that turn light into visual stimuli, including:
- Retina (thin tissue layer in the back of the eye that translates light to the optic nerve)
- Optic nerves (communication pathway between the eye and the brain)
- Optic chiasm (joining together of the optic nerves of both eyes)
- Visual cortex (primary area of the brain that receives and processes light from the retina)
During visual processing, the optic nerve from the right eye joins with the optic nerve from the left to form an X-shaped structure called the optic chiasm. The optic nerves then cross paths and continue on the optic tract to the brain.
The brain is divided into two halves, which are the right side and the left side:
- The left side is responsible for vision in the right visual field of each eye
- The right side is responsible for vision in the left visual field of each eye
The type of hemianopia depends on the location of the disturbance in the brain or visual pathway.
Homonymous hemianopia is the most common type of hemianopia. It results in vision loss on the same side of each eye.
Different types of homonymous hemianopia include:
- Left hemianopia is vision loss on the left half of each eye
- Right hemianopia is vision loss on the right half of each eye
- Inferior hemianopia is vision loss in the lower half of each eye
- Superior hemianopia is vision loss in the upper half of each eye
Heteronymous hemianopia is a bilateral visual field defect on the opposite sides of each eye.
This type of hemianopia results from a lesion on the optic chiasm, the X shape structure where the optic nerves meet and cross.
The types of heteronymous hemianopia include:
- Bitemporal hemianopia is vision loss in the outer part of the visual field in each eye
- Binasal hemianopia is vision loss in the inner part of the visual field in each eye
Depending on the underlying cause of hemianopia, it can be either temporary or permanent.
Symptoms of homonymous hemianopia range from mild to severe and include:
- Disturbed site and missing objects in the visual field
- Blurry or double vision
- Dimmed vision
- Trouble with night vision
- Visual hallucinations
- Visual neglect is when you fail to notice on one side of your visual field
Heteronymous hemianopia symptoms are less severe and usually only cause depth perception and peripheral vision problems.
What Causes Hemianopia?
Stroke is the most common cause of homonymous hemianopia and accounts for 69.7% of cases.1
Other causes of hemianopia include:
- Brain injuries
- Bleeding in the brain
- Brain tumors
- Infection in the brain
- Multiple sclerosis
- Alzheimer's disease
- Invasive surgical procedures
How is Hemianopia Treated?
Hemianopia treatment is dependent on the underlying cause of the visual disturbance. The condition may correct itself over time with spontaneous recovery from a brain injury, stroke, or tumor removal.
Some cases of hemianopia may be permanent and need ongoing treatment to expand your visual world.
These treatment options include:
- Vision restoration therapy to help with reading and dealing with your environment
- Visual rehabilitation to maximize the use of remaining vision and eye movement patterns
- Visual assist devices, including prism glasses
- Using a driving simulator to determine if you are safe to drive
- Learning how to make quick eye and head movements toward the affected side
- Use a straight edge to help direct your eyes when reading
Can You Recover from Hemianopia?
Visual recovery from hemianopia depends on the underlying cause of the blind side and your ability to heal from injury or illness.
Permanent loss of half of the visual fields can affect the quality of life, including:
- Not being able to drive
- Difficulty reading
- Trouble moving around in your environment
- Social isolation
- Anxiety and depression
Hemianopia is the loss of half your field of vision in one or both eyes. It is caused by a stroke, illness, or brain injury. Depending on the underlying cause, it may be temporary or permanent.
Permanent hemianopia can be treated with vision therapy, rehabilitation, and training to move your head and eyes towards the affected side. Learning to live successfully with hemianopia can improve your quality of life and mental health.
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