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Cerebral Visual Impairment: Understanding Causes, Symptoms and Treatment Options
Medically reviewed by Tina Patel, Contact Lens Optician at Feel Good Contacts on 27 July 2023.
- What causes cerebral visual impairment (CVI)?
- What causes visual impairments in cerebral palsy?
- Symptoms and diagnosis for cerebral visual impairment
- How to live with CVI
- How can CVI be treated?
- Is cerebral visual impairment a disability?
Cerebral visual impairment (CVI) is a leading cause of vision loss as a result of brain function, rather than dysfunction in any individual part of the eyes.
Also known as cortical visual impairment, CVI is a disorder of the parts of the brain that process vision. It is most common in children and develops differently depending on the individual. It is important to be able to recognise when this might occur so that it can be identified and managed appropriately in babies and young children.
What causes cerebral visual impairment (CVI)?
Cerebral visual impairment happens when the brain is unable to convert light signals from the eyes into images in the brain. There are several causes of cerebral visual impairment, but most occur in early life as a baby or young child. Most causes of cerebral visual impairment are related to brain trauma.
There are many factors that might pre-dispose a child to CVI, including underlying health problems. Children with other disabilities are more frequently diagnosed with CVI than those without. These can include:
- Developmental disabilities
- Hearing loss
- Cerebral palsy (a brain disorder that causes movement problems)
The physiological explanation for the development of CVI in some children, especially for it to occur among other disabilities, suggests that CVI is a result of brain injury. One of the reasons why CVI is most common in babies and children is because the injuries tend to happen before, during, or shortly after birth. Instances can include:
- Head injury
- Lack of oxygen or blood supply to the brain (sometimes resulting from stroke)
- Hydrocephalus (build up of fluid in the brain)
- Infections in the brain
- Premature birth
- Genetic conditions
Adults can also develop CVI, usually as a result of a stroke or some trauma to the head through violent impact. With CVI, the eyes themselves do not need to sustain damage, but if brain function is lost, vision loss is possible.
What causes visual impairments in cerebral palsy?
Vision problems in people who are diagnosed with cerebral palsy are very common, with 75-90% experiencing some degree of visual impairment.
Most frequently, the vision impairment is a result of damage to the occipital lobe in the back of the brain, which is characterised as CVI.
Symptoms and diagnosis for cerebral visual impairment
Recognising symptoms of cerebral visual impairment in children will happen gradually as the child develops and grows. Some children develop faster than others, so it is important not to jump to any conclusions if the child is experiencing delayed development.
If you suspect that a child has CVI, the only way to get a diagnosis for cerebral visual impairment is to arrange comprehensive eye exam with an eye specialist to determine if there is any problem with the eyes. If no problems can be detected in the eyes, examining the brain will be the next step in diagnosis of the vision loss.
To determine a CVI diagnosis, imaging tools can be used to examine brain function. Tools that might be used include:
- Visual Evoked Response (VER)
- Electroencephalography (EEG)
In children, low vision specialists, caregivers or support workers may identify CVI through behavioural factors such as:
- Inconsistent visual responses to repeated stimuli
- Better responses to familiar stimuli than to new stimuli
- Better attentive response to moving stimuli than static stimuli
- Difficulty recognising and reaching for objects
- Limited response to visual stimuli amid simultaneous non-visual stimuli (music, voices, touch)
- Visual tasks cause fatigue
- Dominant peripheral vision
- Better responses to colour than black and white stimuli
- Better performance for vision for navigation than expected
- Difficulty identifying detail within a busy background
How to live with CVI
To understand visual processing disorders, it is important to understand the specific challenges that people with CVI face, both in terms of lifestyle challenges and in terms of managing and treating the condition.
What is the experience of having cerebral visual impairment?
Visual impairment from CVI prevents those with the condition from processing visual information. That means that they are unable to create images in the brain to help them navigate the physical world around them.
In addition to adapting their lifestyles, people with cerebral visual impairment might struggle with the following additional symptoms:
- Poor visual acuity
- Limited visual field
- Abnormal light response (photophobia or low sensitivity to light)
- Social gaze (avoidant or inattentive gaze)
- Inconsistent fixation
- Recognising faces
- Limited ability to recognise colour and contrast
- Visual fatigue, for example pupils may have periods of good vision and then periods when vision is less good
- Mobility (navigating stairs, steps and hills)
Difficulties in these areas can create barriers for people with CVI to complete everyday tasks without reasonable adjustments.
Methods of managing cerebral visual impairment
For parents with children who experience CVI, early intervention and therapy is recommended. Educational support can be provided to help children adapt to learning practices and get the best out of their abilities.
Reasonable adjustments can be made in education and in the home to make living with CVI more accommodating. Such adjustments include:
- Clearly signpost obstacles (e.g. steps and stairs)
- Use larger size font for words
- Storage consistency (keep similar items in the same places)
- Use simple visual images (reduce visual clutter)
- Provide a desk slope to keep images in central visual field
- Typoscope (a small window cut into a piece of card)
- Identify and use key routes and consistent landmarks
- Use a consistent identifier to help facial recognition difficulties (e.g. colour consistently in clothing, meeting points, buddy scheme)
How can CVI be treated?
There’s no cure for CVI. Some people with CVI do regain partial vision over time naturally, but there is no medical explanation for this and cases are rare.
Rehabilitation is the best option to help those with CVI optimise the vision they do have as well as create solutions for living without vision. Vision therapy for cerebral visual impairment is sometimes effective in enhancing peoples’ abilities to cope with their condition.
Research and funding into CVI treatments
Ongoing funding and research is being undertaken globally to better understand the CVI in the hopes of developing effective treatments for vision loss related to cerebral vision impairment.
At current, there are few treatment options for cerebral visual impairment. Organisations like the National Eye Institute (NEI) in the USA funds research to develop insights and treatments continuously. Currently, work is being done with virtual reality (VR) to help scientists understand how CVI patients process vision compared to visually impaired people with eye-related limitations.
Is cerebral visual impairment a disability?
Cerebral visual impairment (CVI) is a visual processing disorder that prohibits people who suffer with the condition from translating visual information from the eye into images that can be understood by the brain. Most cases are developed before, during or shortly after birth and the symptoms are life-long. While adults can develop CVI from sustained brain injuries, partial vision recovery is possible in a few cases.
People with CVI are classed as visually impaired, varying in degrees based on individual abilities. Visual impairment is a form of disability that requires ongoing support. As there is no cure for CVI, rehabilitation and reasonable adjustments to living conditions are necessary to help visually impaired people to navigate their homes, localities and complete daily tasks.