What is it?
As opposed to vision problems caused by conditions of the eyes, cerebral visual impairment (CVI) refers to vision problems caused by the brain not being able to interpret the information from the eyes passing along its visual pathways.
Children affected usually find it difficult to focus on objects, especially if multi-tasking, and may have difficulty recognising people and objects against different backgrounds. Distractions, such as noise, can affect what the sufferer is seeing.
CVI is the most common type of visual impairment in children in the developed world.
What are the symptoms?
Cerebral visual impairment affects different children in different ways and to different degrees. Here are some possible symptoms to watch out for:
- Vision is inconsistent, for example it seems better when the child is healthy, and worse when they are ill, or tired.
- Uncoordinated movement
- Bumping into things when walking and talking
- Missing, or knocking over objects when trying to pick them up
- Inability to focus on objects for any length of time
- Getting lost, anxious, or distressed in busy or crowded areas
- Difficulty recognising familiar objects or people
- Severe difficulty copying down information
What causes cerebral visual impairment?
There are several possible causes of CVI, although in many cases it may not be obvious which cause is responsible. Some of the major causes are:
- Asphyxia, hypoxia (not enough oxygen in the blood cells) or ischemia (insufficient blood supply reaching the brain), or any episode resulting in lack of blood or oxygen supply to the brain. These may have occurred during birth.
- Head injury
- Hydrocephalus – fluid collects in the cranium, causing pressure, which affects the brain.
- Meningitis, encephalitis, and other central nervous system infections.
- Cerebral palsy
- Lesions caused by a stroke or bleed
- Autistic spectrum disorders
Children born prematurely (before 34 weeks) should also be closely monitored for signs of CVI.
How can it be prevented?
Due to the nature of the causes, cerebral visual impairment is impossible to prevent. Children who have been affected by the possible causes listed above should be carefully monitored by their parents and doctors for signs of CVI.
What is the treatment?
While there is no cure, there are many ways to support a child suffering from CVI. Children with CVI and their families are entitled to support from their local authority in finding specialist teachers to aid their educational, social and emotional development. As sufferers can find it difficult to recognise familiar objects, keeping one with the child throughout the day can help them in recognising it in different environments, while using brightly-coloured objects and minimising background noise can help the child to ‘practise’ using the vision they have.