HEMIANOPIA: ONE-SIDED VISION LOSS CAUSES AND TREATMENT

Medically Reviewed by Dr. Sony Sherpa, (MBBS) - September 02, 2024

Hemianopia, also known as Hemianopsia or unilateral blindness, is an ailment that affects a person's ability to see one side of their vision. Hemianopia affects a person's visual field, which is the area that a person can see without moving their eyes.^[1]

It affects up to 70% of those who suffer a stroke. In other conditions that lead to Hemianopsia, the prevalence varies from 19% in those with traumatic injuries to 39% in children with tumors.

This blog explores the types, causes, symptoms, diagnosis, and treatment options for Hemianopia.

Types of Hemianopia

This condition is categorized into different types, depending on the affected area of the visual field.^[2]

The most common types of Hemianopia are:

• Homonymous Hemianopia affects the same side of the visual field in both eyes.

This type is further divided into left or right homonymous, affecting both eyes' left or right side of the visual field.

• Heteronymous Hemianopia affects different sides of the visual field in each eye.
• Superior Hemianopia affects the upper half of the visual field.
• Inferior Hemianopia affects the lower half of the visual field.
• Bitemporal Hemianopia affects both eyes' outer (temporal) portion of the visual field.
• Contralateral Hemianopia with Macular Sparing is characterized by a loss of vision on one side of the visual field but with the central vision (macula) remaining intact.

Hemianopia classification also includes complete or partial types, depending on the degree of the visual field deficit.

• Complete Hemianopia refers to a total loss of vision on one side.
• Partial Hemianopia refers to a partial loss of vision on one side.

Causes of Hemianopia

Hemianopia results from damage to the brain's optic nerves or visual cortex.

Common causes include:

• Stroke: A stroke happens when there is a disturbance in blood flow to the brain, leading to brain damage. Brain damage can result in Hemianopia if the affected brain area is responsible for processing visual information.
• Brain tumors: Tumors in the brain can also cause Hemianopia if they reside in areas responsible for processing visual information.
• Eye diseases: Certain eye conditions, such as glaucoma and retinal detachment, can also cause Hemianopia if they affect the optic nerve or retina.
• Congenital conditions: In some cases, Hemianopia can be present at birth due to a congenital condition affecting the visual pathways in the brain.

Rarer causes encompass infection, seizures, toxin exposure, or aneurysms.

Symptoms and Diagnosis of Hemianopia

The most common symptom of Hemianopia is a loss of vision on one side of the visual field.

One-sided vision loss can manifest as:

• Difficulty seeing objects on one side
• Bumping into objects on one side
• Difficulty reading
• Difficulty driving

Other symptoms may include headaches, dizziness, and difficulty with balance and coordination.

To diagnose Hemianopia, a doctor will perform a visual field test, which involves having the patient look at a screen and indicate when they see a light or object appear. This test can determine the extent and location of the visual field loss.^[3]

Other tests, such as an eye examination, a brain MRI, or a CT scan, can also help determine the underlying cause of the Hemianopia and rule out eye diseases.

Hemianopia Treatment

Unfortunately, there is no cure for Hemianopia. However, treatment options are available to help manage the condition and improve the quality of life.

Medical Interventions

Medical interventions aim to address the root cause of Hemianopsia.

Depending on the specific circumstances, the following options may help treat the condition:

Tumor Control: Surgery can treat Hemianopia caused by a tumor compressing optic pathways. It can relieve pressure on nerves and improve vision. Medication or radiation therapy can help shrink or control tumors as an alternative or complementary treatment to surgery, alleviating Hemianopia symptoms.

Eye Disease Treatment: Common treatments for eye diseases include eye drops, medications that lower eye pressure, steroids, and laser therapy. Corrective eye surgeries may treat the condition if severe and include retinal detachment surgery and trabeculectomy.

Stroke Prevention: As stroke prevention is crucial in managing stroke-related Hemianopia, medications such as antiplatelet drugs (e.g., aspirin, clopidogrel) or anticoagulants may be prescribed to reduce the risk of further stroke occurrence.

Most other causes of Hemianopia require rehabilitation, monitoring, and treatment that aims to manage symptoms.

Rehabilitative Therapies

Rehabilitative therapies focus on improving visual scanning, spatial awareness, and compensatory strategies.

Vision training programs involve eye movement exercises and visual scanning activities to achieve visual rehabilitation. Working with a therapist or utilizing specialized software can be beneficial in this process.

NovaVision's Vision Restoration Therapy (VRT) is a non-invasive computer program that aims to improve visual function in individuals with visual field defects caused by traumatic brain injury. It utilizes neuroplasticity principles to stimulate remaining visual pathways and promote functional vision recovery. However, the effectiveness of VRT is still under debate, with the best results showing a 5% increase in field vision.^[4]

Occupational therapy can assist individuals with Hemianopia with navigating their daily lives. Occupational therapists can guide environmental modifications, task-specific training, and techniques to improve functional independence.^[5]

These therapies can help individuals adapt to visual field loss and enhance their overall functionality.

Assistive Devices and Technological Aids

Assistive devices and technological aids can support individuals with hemianopsia in their daily activities. They aim to improve visual function and compensate for the visual field loss.

Some standard assistive devices and technological aids include:

• Neuroprosthetic devices, including prism glasses and mirrors, can enhance the visual field, aiding those with Hemianopia to see objects in peripheral vision and improve spatial awareness. These devices work by shifting the image from the blind side to the seeing side, allowing the person to see more of their surroundings. They cannot assist with complex visual tasks like driving.^[6]
• Tech aids and apps can help with Hemianopia, offering visual scanning, text-to-speech, and task reminders.

For optimal Hemianopia management, it is crucial to engage with medical practitioners or experts to identify the optimal treatment alternatives related to the root cause of the illness. These professionals can offer tailored advice and assist individuals in making knowledgeable choices about the condition's control.

Living with Hemianopia

Living with Hemianopia can present several challenges. Hemianopia makes navigating environments, detecting hazards, and interacting with others challenging. It can cause limited awareness on the affected side, affecting engagement with the environment and daily activities.

Affected activities include:

• Driving, walking, and navigating crowded spaces due to difficulty detecting objects, pedestrians, or vehicles approaching from the affected side.
• Reading and writing due to reduced speed and accuracy.
• Daily activities like cooking, cleaning, and grooming due to difficulty in visually scanning surroundings and coordinating tasks.

The outlook for individuals with Hemianopia varies and can depend on the underlying cause, severity, and individual circumstances. While there is no cure for Hemianopia, strategies, and resources are available to help improve quality of life.

Here are other ways to help you deal with the problem^[7]:

• Make sure to take in all your surroundings before navigating them.
• Have someone walk with you to help you navigate.
• Use images in your environment and other visual aids to help you see what is missing.
• Colored tape or markers can help you to see marked objects.
• Organizing your home environment to make tasks easier, such as placing objects on the unaffected side of your vision.
• Practice turning to the side while seated or standing to see more.
• Use a ruler or straight edge under each line when reading.
• Speak to your doctor about driving. A driving simulator can indicate if you can drive safely.

Living with Hemianopia is emotionally challenging as it impacts independence and daily tasks. Seek support from loved ones and professionals, join groups for social support, or seek therapy to manage the emotional impact.

Future Research on Hemianopia

As technology advances, there is ongoing research on potential treatments for Hemianopia. Some areas of research include:

• Brain-computer interfaces: Researchers are exploring the use of brain-computer interfaces to help improve visual processing and compensate for visual field loss in people with Hemianopia.^[8]
• Stem cell therapies: Stem cell therapies have potential as curative treatment options for Hemianopia caused by nerve damage. Studies show that stem cells can potentially regenerate damaged nerves, restoring lost vision.^[9]
• Virtual reality: Virtual reality may aid vision training and rehabilitation for people with Hemianopia.^[10]

Conclusion

Hemianopia is a visual field loss condition that various neurological conditions can cause. While there is no cure, treatment options are available to help manage the condition and improve quality of life. With the help of rehabilitation strategies and coping strategies, individuals with Hemianopia can learn to adapt and live a fulfilling life. As research continues, there is hope for more effective treatments and potential cures for this condition.

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