Cerebral visual impairment

CVI is caused by damage to the parts of the brain which deal with vision.

In children, this damage most commonly occurs before, during or shortly after birth. However, this damage can happen at any age.

Common causes of CVI in babies and young children include:

• being born prematurely
• lack of oxygen or blood supply to the brain
• fluid build-up in the brain (hydrocephalus)
• infection
• injury to the head
• certain genetic conditions.

Causes in older children include:

• complications of heart or brain surgery
• lack of oxygen or blood supply to the brain (such as stroke)
• inflammation of the lining around the brain and spinal cord (meningitis)
• inflammation of the brain (encephalitis).

Causes in adults can include:

• traumatic brain injury
• infection
• stroke
• dementia.

CVI affects how the brain makes sense of what the eyes see. People with CVI can have mild to severe challenges using their vision. Some people have good vision when measured on a letter or picture chart but find it hard to use their vision for everyday tasks. This happens because their brain finds it difficult to process visual information. Some people can also have reduced vision as part of their CVI. This means they will struggle to interpret what they see and have reduced vision.

CVI affects everyone differently and uniquely. It depends on the specific areas of the brain that are damaged.

There are emotional and environmental factors that can make a person with CVI see less well compared to when they are relaxed and in simple surroundings. Factors such as stress and anxiety, background noise, lots of detail, clutter or patterns on an object or in the surroundings, may make it harder for someone with CVI to see.

Someone with CVI might have difficulty with:

• seeing fast moving objects, such as vehicles or people
• seeing while moving, such as walking or moving in a wheelchair
• identifying objects below eye level, such as their feet or kerbs
• recognising a familiar face in a crowd
• adapting to changes in floor surfaces e.g. moving from   carpet to a hard floor
• finding their way around a new place
• finding the start of a line when reading
• finding items in a cluttered environment
• seeing and hearing at the same time, especially when there is a lot of background noise.

It can be difficult to understand what your child with CVI can see because CVI can cause a variety of visual symptoms. Some children can see more easily when they are surrounded by familiar objects. This is because their brain has had repeated opportunities to recognise the objects.

Observing a child with CVI is an important way to assess how it is affecting them. There are some key questions that can help you have a better understanding of the way CVI affects your child’s vision such as:

• At what distance do they respond to an object of interest?
• How does contrast sensitivity affect what they can see?
• At what distance, if at all, can they respond to faces and facial expressions?
• Do they prefer or respond better to particular colours? If unsure, try “warm” colours such as red, orange or yellow, as these often lead to a better response.
• How do they respond to large clear targets? This can be used to assess how big or small something needs to be for the child to see it.
• Which areas of the visual field do they respond in?
• How long does it take for them to respond?
• What detail can be seen and responded to?

There’s no single test to check for CVI. If you suspect that your child has vision problems, the first step is getting an eye examination. This is usually with an optometrist (optician). The optometrist can assess:

• visual acuity
• how well the eyes work together to give depth perception (binocular vision)
• visual field
• contrast sensitivity
• colour vision
• the health of the eyes.

If the examination doesn’t find an eye condition to explain your child’s symptoms, it might mean the issue is with their brain. Your child will need to see an ophthalmologist (eye doctor) who’s familiar with CVI to get a diagnosis. Your child may also need to visit other specialists. These can be a paediatric neurologist or neuro-ophthalmologist (doctors specialising in conditions affecting the brain).

The doctor will examine your child and ask about their medical history. They may also order scans of your child’s brain. CVI can be difficult to diagnose so may take some time. The correct diagnosis is key to getting your child the help they need. If there are concerns about your child’s vision that can’t be explained by an eye condition or a need for glasses, ask your doctor if it could be CVI. This is especially important if your child has had a brain injury.

Unfortunately, there is no treatment or cure for most types of CVI. However, visual rehabilitation can help people with CVI to use their vision better. For some people the visual symptoms caused by CVI can improve over time. This is especially true if their visual challenges are identified and managed effectively.

Early intervention, therapy, educational support and other special services can help babies and children with CVI develop and learn. If your child has CVI, working with their doctors to find the best plan for their care is important.

Glasses or contact lenses may be needed to correct any focusing errors (such as long or short sightedness). If glasses are needed, they help make vision clearer and more focused. This is especially important for children as the brain grows and develops.

Using large, widely spaced print and a ‘letterbox’ to see one word at a time can make reading easier. Removing distractions from the environment and other senses like hearing and touch, may also help.

Low vision aids can help make the most of the sight a person has by making things bigger, brighter and bolder. Using contrasting colours can also help to make some things stand out. An example of this could be making the edges of steps stand out using contrasting colours. You’ll be more comfortable if your environment causes you minimal glare. This can involve the lighting around you and the devices you’re using.

You can find out more in our Making the most of your sight booklet which you can find on our website or by calling our Helpline.

Glare shields may be helpful for light sensitivity. Our factsheet on light sensitivity gives more information on managing glare. You can find this on our website or by calling our Helpline.

Here are some tips to manage visual difficulties caused by CVI:

• Give extra time. Someone with CVI may take longer to process what they are seeing. It can also be tiring, so give regular breaks.
• Reduce clutter. Have separate storage for favourite items and always store in the same place.
• Reduce distraction. Patterns can make it difficult to see an object.
• Use contrasting colours. Black on white can make an object easier to see.
• Reduce noise. Background noise can be distracting, making it difficult to see and hear at the same time.
• Position objects where they find it easiest to see. Some children with CVI find it difficult to use their lower visual field.

If you have any questions about cerebral visual impairment, we are here for you. Just call our helpline on 0303 123 9999.

The CVI Society Homepage — The CVI Society and CVI Scotland are also useful resources for further CVI information and support.