There's some evidence to suggest a higher prevalence of colour blindness in those with cerebral palsy than in the rest of the population, not only because of complications arising from other visual impairments, but also due to suspected increased defects in genetic code. Further research is in progress in the USA to understand the statistics and factors underlying this.

Where colour vision deficiencies are present in a non-verbal child which have been acquired from other causes such as retinitis pigmentosa, the colours a child has problems with may be different to those which cause problems for someone with genetic Colour Vision Deficiency (CVD) (common red/green colour blindness).

At present, it's not possible to diagnose, simulate or fully appreciate what such a child might be able to see. You could consider trying out the Colour Blind Awareness Indicative Test for CVD in Non Verbal Children cards to work out the potential problems colours for each individual child and avoid those colours when teaching that child in the future. Cases of acquired CVD are relatively rare in children – around 5% of cases of CVD – and the following advice therefore refers to genetic red / green colour blindness only. Contact Colour Blind Awareness for more information about acquired CVD.

How to identify CVD in a non-verbal child

As mentioned earlier, although under development, at present there are no formal tests available in the UK to diagnose CVD in non-verbal children. Contact the Colour Blind Awareness Organisation for further details of indicative tests using eye gaze or activities for children using hand-grabbing techniques which can help to identify severe colour vision deficiencies in non-verbal children. A child will not be suitable for indicative testing for CVD unless they are able to indicate differentiation between ‘same’ and ‘different’.

If you suspect CVD in a non-verbal child, what next?

Update the child’s communication passport - note possible problem colours and ensure the symbol book is colour blind compliant too. In future try to avoid all combinations of colours the child has found it difficult to tell apart in the test. Remember to include colour blindness as part of the Early Years Moving Up booklet. Consider all the methods you are using to communicate with the child including communication books, encoding, keyboards and software packages. Be aware that even though a software package might have been put together by a specialist in cerebral palsy this does not necessarily mean the software takes account of colour vision issues.

Communication boards and books

If you suspect a child might be colour blind, select a white background for symbols and try to avoid colour coding unless you have clearly established that the child can see the specific colours you have chosen for colour coding different subjects.

Encoding

As colour matching is a vital element of encoding, make sure you don’t use colours that could potentially cause problems, especially red as a contrast to green.

If possible consider using different shapes for symbols or shapes instead of colour.

‘Co-ordinate encoding’ using colours will probably not work for a child with a colour vision deficiency because of the range of colours needed to make up the co-ordinates but you could consider using symbols or numbers instead of colours.

Keyboards or on-screen keyboards

Think carefully before colour coding keyboards. With younger CVD children avoid using different colours for different lines on the keyboard or to colour in vowels. Again, consider using symbols or shapes instead of colours. If you are using an on-screen keyboard avoid background colours where possible and check carefully for good contrast between the text and background chosen. If in doubt ask the child if they can easily see the text.

Software for pre-school children

For colour blind children it's much easier to read symbols against a white background than a coloured one. Small images and text are difficult to read against dark backgrounds.

Grouping verbs, nouns according to colour is not appropriate for colour blind children and may add to confusion, so always default to a white background

To give a better indication of how people with different deficiencies see colours differently, a ‘normal vision’ image of coloured pencils has been altered to simulate severe loss of green vision (left) and severe loss of red vision (right).

Note that although some colours appear the same for both conditions, there are colours that look different – so if you have green loss you can see a difference between these particular shades of green and orange but if you have a red loss you can’t. That's why it's important to work out with individual children the colours they can distinguish between and those they can’t.

Where to find resources

  • colouring pencils marked with the name of their colour
  • stickers printed with the names of colours for paint pots, crayons, storage boxes etc. for both home and classroom use
  • indicative Colour Vision Deficiency (CVD) testing kit for non-verbal children
  • unique spectacles for teachers to wear which show a colour blind world (Variantor)
  • to arrange visits for staff training / indicative testing of students.

CVD: How to obtain further help

Refer the child to the Specialist Teaching Services / Visual Impairment team at your Local Education Authority who should be able to advise you about how to support the child’s specific type of colour vision deficiency. Refer to the Colour Blind Awareness Organisation’s website for more detailed information including how to support CVD children at home. You will find a huge range of visual images to clearly demonstrate the issues faced by people with CVD together with tips to manage things day to day.

Acknowledgements

With thanks to Laurel Allen, Speech and Language Therapist, The PACE Centre, Aylesbury and Dr Caterina Ripamonti, The Colour Vision Research Labs, UCL, London.

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