Hemianopia

What are the different types of hemianopia?

Heteronymous hemianopia

Heteronymous hemianopia means your vision loss is on different sides in each eye. This can be either:

• Bitemporal hemianopia - A loss of visual field in the outer (also called temporal or lateral) half of both the right and left visual fields.
• Binasal hemianopia - The loss of the visual fields nearest the nose, in the inner half of each eye.

Homonymous hemianopia 

Homonymous hemianopia means your vision loss is on the same side (left or right) in both eyes. Left hemianopia causes a loss of visual field in the left half of each eye. Right hemianopia causes a loss of visual field in the right half of each eye.

• Complete homonymous hemianopia - involves all of the visual field from the centre outwards.
• Partial hemianopia involves only part of the visual field - some field of vision remains on the affected side.
• Quadrantanopia means your vision loss is in one quarter of your visual field (such as top left). This can be either:
• Superior quadrantanopia - A loss of visual field in the upper half of each eye to either the right or left side. 
• Inferior quadrantanopia - A loss of visual field in the lower half of each eye to either the right or left side.

What causes hemianopia?  

Hemianopia is caused by a disruption in the later part of the visual pathway (the pathway that carries signals from each eye to your brain). 

The most common cause of hemianopia is stroke, followed by trauma (injury) and tumours.

However, it can also be caused by:

• Abnormal blood vessels
• Alzheimers
• Dementia
• Epilepsy
• High Pressure in the brain
• Hydrocephalus
• Lymphoma
• Multiple sclerosis
• Neurosyphilis
• Neurosurgical procedures
• Shaken Baby Syndrome

What are the signs and symptoms of hemianopia?

The symptoms of hemianopia can range from mild to severe. Because it affects one side of your visual field, it can feel like you have lost all sight in one eye, although it is actually partial loss in both eyes.

Other signs include:

• distorted or blurry sight
• not being able to see from the affected side
• spatial awareness problems
• bumping into things, because you haven't seen them
• your vision appears dimmed
• reduced night vision
• visual hallucinations
• difficulty reading

If you are experiencing any visual difficulties, it’s important to have your eyes examined by an eye care specialist so you can get an accurate diagnosis. If you have hemianopia, you should receive clear information about your condition and be offered treatment if it is appropriate.

Get support for coping with vision loss

Is hemianopia serious?

Although hemianopia does not affect all of your vision, it can have a major impact on your life and independence. Hemianopia affects reading and usually means you shouldn't drive. Moving through different environments - such as crossing roads, or navigating around crowded places like shopping centres - can be challenging.

It can also be more difficult to find things, if you can't see to the left or to the right of your field of vision. 

People can recover from hemianopia, although that is more likely if hemianopia is caused by inflammation rather than a stroke. Only around 15% of stroke survivors will fully recover their vision in the weeks after their stroke. 

How is hemianopia diagnosed?

The usual way to diagnose hemianopia is a visual field exam. Your doctor may ask you to count their fingers or spot an object at the side of your visual field. Perimetry tests can give a more accurate assessment, by using flashing lights whilst you focus straight ahead.

Magnetic resonance imaging (MRI) of the brain can also be used to diagnose the underlying cause of the brain injury leading to hemianopia.

What are the treatments for hemianopia?

First, the cause of hemianopia, such as stroke, tumour or head injury, is treated. This may help restore some function of the visual pathway in the brain. Sometimes your vision will improve over time without any treatment, but in many cases it doesn't. 

An eye clinician may recommend different strategies to help with your vision, such as:

• Visual scanning exercises - involve looking to the left and right side systematically to help improve your awareness of the visual field loss and remind you to look into your blind side. For example, you could practice keeping your head still and moving your gaze around to your affected side of vision. Or using puzzles and word search games to improve your visual detection skills.
• Prismatic correction glasses - can help widen your field of view in some circumstances. The prism is worn on the side of the visual field loss, creating a blurred, overlapping image that you can see on your 'good' side. This acts as a prompt to look towards the blind side.
• Visual restorative treatment for hemianopia - Different strategies are available that aim to help you to interpret visual information by building awareness of moving images in your blind field of vision.

There are also practical things you can do to help you to cope with vision problems (see What can help hemaniopia, below).

What can help hemianopia? 

Sometimes hemaniopia can't be cured. In these cases, there are some simple things that can help you to make the best use of your remaining sight.

• Reading strategies - like holding a straight edge (such as a non-transparent ruler) under each line or text, or a piece of card with a rectangle cut out, can make easier to focus on a line of text at a time. Placing a hand or marker on the edge of the page can help you to see where the page margin is. It may also be helpful to tilt the text at an angle and reading it vertically rather than horizontally.
• Magnifiers - can be helpful when reading as it can be easier to scan larger print than standard size print.
• Good lighting - ideally positioned to the side rather than behind you (which can cause shadows).
• Support from friends or family - like having a walking partner who can provide guidance when moving around challenging environments, so you don't bump into or trip over things.

• Reducing clutter - or the number of objects that are on surfaces at home, as clutter can make it more difficult to pick out individual items.