Vision

The brain’s role in vision

Vision is the skill that allows us to see the world around us. When we look at the world, a complicated set of processes takes place between the eyes and the brain.

First, the eyes take in visual information from the world around us, such as colours, shapes, movement, objects and people.

This information is passed from the eyes to the brain through electrical signals, along the optic nerve. The brain is then responsible for making sense of the information it has received. It will connect visual information with information stored in memory to give meaning and context, for example seeing the facial features of a loved one and being able to recognise them, seeing light outside and knowing that it is a sunny day or seeing a red traffic light and knowing to stop.

Some of the things the brain needs to do to decode information that it receives from the eyes are:

• Process and merge information received from both eyes;

• Process information across the visual field (including peripheral vision);

• Process the shape and colour of objects;

• Process the movement of objects;

• Process the location and position of objects in space (for example, are objects near or far, to the right or left, etc.);

• Recall information from memory to recognise and make sense of visual information.

Various parts of the brain are involved in processing these different aspects of vision. For example, at the back of the brain is an area called the occipital lobe, which is responsible for interpreting information such as colour, shapes and movement. At the sides of the brain are the temporal lobes, which are involved in recognising objects. Injury to these parts of the brain can therefore affect these aspects of vision.

Types of visual problems after brain injury

The brain has a key role to play in our ability to see. It receives visual information from our eyes, such as light, colour and shapes, and makes sense of it so that we can see the world around us. If parts of the brain involved in processing vision get injured, the result can be a range of different types of visual problems.

This section describes some types of visual problems that can develop after brain injury.

Blurred or double vision

Vision may become blurry after brain injury, causing problems with distinguishing details and recognising things. Double vision, also called diplopia, causes two images of a single object to be seen at the same time. This happens because the brain becomes unable to merge the information it is receiving from both eyes.

Visual field loss

Vision in a section of the visual field may be affected, so that a part of it appears blurry, dark or distorted. This may occur around the edges or at the centre of the visual fields, across half of it (known as hemianopia) or across a quarter of it (known as quadrantanopia).

Nystagmus

Nystagmus is a condition in which there is an involuntary, rhythmic shaking of the eyes. The eyes might move from side to side, up and down or in a circular motion. This can cause symptoms such as vertigo, nausea or headaches.

Blindness

Complete blindness after brain injury is rare. For this to happen, there must be significant damage to the optic nerve, multiple parts of the visual pathways or areas of the brain involved in processing vision. Blindness as a result of brain injury is also called ‘cortical blindness’.

Photophobia

An increased sensitivity to light that causes discomfort or pain is called photophobia. Some people with photophobia use darkened sunglasses to cope, however research suggests that in some cases this might actually prolong or worsen sensitivity to light.

Colour or motion vision changes

Colour vision may be affected, so that colours may appear different, washed out or, in more severe cases, in shades of grey. Motion vision problems, called akinetopsia, can cause moving objects to appear as static images that move in a jagged way rather than smoothly.

Depth perception changes

Otherwise known as stereopsis, depth perception allows us to judge the distance between objects so that we can assess how far away something is. People with depth perception changes will struggle to identify the distance between things, causing difficulties with reaching out for objects, climbing stairs safely, driving or navigating around.

Squint

If eyes are pointing in different directions and are not working together, this is called a squint, or strabismus. This can cause some of the problems described earlier in this section.

Impact of visual problems

Vision is one of our most important senses, so when it is affected it can affect activities completed, skills, safety, emotions and quality of life. Some examples of these are given below.

Balance problems and dizziness

The body’s balance system relies partly on visual information received from the world around us. Visual problems can therefore cause problems with dizziness and balance, which you can read about in more detail on Balance problems and dizziness.

Driving

Being able to drive relies on being able to see and navigate on roads, read road signs and process traffic light changes, among other visual processes.

Driving also relies on the ability to quickly and accurately interpret visual information from across the visual field. Hazards can appear on the road at any time, and a driver must be able to detect and respond to these quickly.

Some modern cars have hazard alert systems that may partly compensate for some forms of visual problems. However, in many cases this will not be enough to keep a driver with serious visual problems safe on the road.

If you have visual problems after a brain injury, you must inform the relevant licensing authorities. Failure to do so could result in a fine of up to £1,000. More information on how to cope with changes in driving ability after brain injury is available on Driving.

Employment and education

There are a wide range of tools, apps and equipment that can be used to compensate for visual problems within the workplace or when studying. Screen readers, adapted environments and access technology can all help. In some cases, it may be possible to modify the work to make it more suitable.

Under the Equality Act (2010), employers are legally required to make ‘reasonable adjustments’ for employees with a disability within the workplace. Find out more about this on Work and employment.

Reading

Many people read for pleasure, but it is also a vital skill that keeps us safe and oriented within the world.

Reading material such as books or website articles are often available or can be converted into accessible formats. For example, audio books, increased screen brightness, text-to-speech readers, smartphone magnifiers and specialist lenses can be used to help. Reading apps can also be helpful.

Rotating pages when reading can help with some visual problems, while using tools such as bookmarks or sticky tabs can also sometimes help.

Socialising

Making arrangements, recognising people we are meeting with or seeing where we are going can be challenging, or even risky, with some types of visual problems.

It might be helpful to talk honestly with your friends about any visual problems (or indeed any effects of brain injury) that are causing you difficulties when socialising. Suggest making arrangements or meeting in environments that are comfortable, suitable and safe for you.

You can also consider using your Headway Brain Injury Identity Card in social settings to quickly explain to others when you need support with visual problems, or other effects of your brain injury.

Mental health

Living with the effects of brain injury, including visual problems, can make some brain injury survivors feel a sense of loss, depression, worry or anger. These are all normal and understandable emotions to feel. Visual problems can change one’s perception of and ability to navigate around the world, and this can be particularly worrisome. Mental health problems such as depression and anxiety may develop as a consequence of these changes.

Diagnosing and treating visual problems after brain injury

Professionals involved in diagnosing and treating visual problems

The visual pathway is very complicated, as there are different processes that take place between the eye and the brain. To diagnose visual problems after brain injury, clinicians may first have to find out whether the problem relates to the eyes, the brain or both.

If you have concerns about your vision after brain injury, you should start by talking to your GP, neurologist or optician. They may be able to investigate themselves or refer you on to a more specialised professional if needed.

A brain injury survivor with visual problems may be able to access support from a neuro-ophthalmologist. These are eye doctors that specialise in the brain’s role within the visual system. As this is a highly specialised role, neuro-ophthalmologists are not always commonly available across the UK.

Ophthalmologists, orthoptists or opticians can also diagnose and treat various visual problems after brain injury, and are generally much more accessible. Some of these professionals may also work in private practice.

Investigating visual problems

In some cases, basic visual tests such as visual acuity or visual field tests can be completed to investigate visual problems. When colour vision is affected, colour vision tests such as the Ishihara Plate Test can be used.

Brain scans may need to be performed using neuroimaging tools such as computerised tomography (CT) or magnetic resonance imaging (MRI).

Treating visual problems

Visual problems after brain injury are often treated in an eye clinic in hospital. Some hospitals have Eye Clinic Liaison Officers who can help with getting appropriate support. You should always start by talking to your GP or neurologist about getting a referral to an eye clinic.

As with some of the effects of brain injury, there may be no way to actually cure some types of visual problems. However, after investigating, clinicians can still help by offering the following where relevant:

• guidance on living with visual problems, such as strategies you can use to cope;

• recommendations of visual aids and adaptive equipment to help at home, at work, or when completing activities;

• exercises for retraining your eyes;

• prescriptions for specialist glasses using tinted, prism or magnifying lenses

• prescriptions of medication;

• advice on organisations that can help with visual problems;

• directing to psychological services that can help with the emotional impact of living with visual problems after brain injury;

• discussing and arranging surgery, if needed.

Tips for coping with visual problems after brain injury

As there are different types of visual problems after brain injury, there is no single way of coping with them. Therefore, the strategies that will be most effective for you will depend on the type of visual problem you have and how it personally affects your life. In this section we share some tips for coping with visual problems. Some may be useful and relevant to your circumstances, while others may not. Explore different ideas to see what works for you.

This information has been produced with expert guidance from Professor Alexander Leff, Professor of Cognitive Neurology and Consultant Neurologist at the UCL Queen Square Institute of Neurology, and Mr Tom Eke, Consultant Ophthalmologist at Norfolk and Norwich University NHS Foundation Trust.

This information was last reviewed in 2024.