A different perspective: colour vision deficiency

There are several forms of CVD, the most common being red/green. Some people cannot differentiate blue and yellow, and some see no colour at all, though this is rare.

The problems with seeing colours do not just apply to the pure colour, but to any mixture of colours. For example, children with red/green CVD may not just confuse red and green, they may be unable to differentiate any colours which contain red or green, for example they may ‘see’ purple as blue because they cannot perceive the red element of the light spectrum which is added to blue to form the colour purple. Therefore reds, greens, oranges, browns, purples, blues and greys may all be impossible to identify accurately.

Most children with CVD cope well as they quickly learn contextual and other cues, such as shade, to assist them to differentiate colours more accurately. Some children may not know that they see things differently from others.

Some children with CVD will try to hide their condition and it is therefore important that classroom practices take account of the needs of these pupils.

Adopting the suggestions below can help ensure you are not unwittingly disadvantaging undiagnosed CVD pupils in your class.

From Early Childhood Education to Primary Education

Identification:

• When playing with crayons, blocks or other coloured objects ask children to group items of the same colour together (reds, blues, yellows, etc). Over the next few weeks and months try to take notice of those who struggle to see if they continue to have trouble. If so, it is possible they have a colour vision deficiency.
• Listen out for chance remarks by children that may indicate the condition.
• If you suspect a child has CVD, discuss this with the parents. They may want to seek a free colour vision assessment for their child, either from an optician or a local vision and hearing technician available through your District Health Board.

Being colour-vision friendly:

• Check books for coloured text on coloured pages, eg, for some children with CVD a poem written in red on a blue page will be difficult to read, and for some red on green will be impossible.
• Teach CVD children the ‘correct’ colours for everyday items so that they know that strawberries, Santa’s outfit, etc, are red, even though they ‘see’ them as murky green. 
• CVD children can learn to identify many, but not all, colours they can’t perceive by using context cues and shade rather than hue.
• If using coloured counters, etc, to help with say, maths, check that child with CVD can differentiate the colours used. Many teaching aids are in primary colours but an affected child will ‘see’ red and green as the same colour. Board games often cause problems for this reason.

Years 7-13

Being colour-vision friendly:

• Consult with the student to find out where they might have problems as by this age they will be able to vocalise any issues.
• In science, children with CVD might not be able to read litmus paper in order to carry out chemical titrations, so it is useful to consider the use of other acid-base indicators as a backup. They may also struggle to identify a material by its colour when burnt or understand colour diagrams in biology textbooks, etc. In lessons you can use a buddy system, and when setting practical tests be mindful of these issues.
• Graphs and charts use colour to illustrate facts. Use secondary indicators such as labelling, patterns and shading rather than, or in addition to, colour, and try to avoid red/green shading in particular for graphs.
• Food technology students may not be able to cook meat properly, distinguish between ripe and unripe fruit or use colourings and decorations correctly. Assignments from students with CVD may appear visually ‘boring’ to read as colour may not be used to its full effect to make statements.
• Always bear in mind that textbook manufacturers do not usually take account of the needs of children with CVD. In particular geography and atlases, science, maths and IT textbooks often present information that these pupils are unable to access.
• Make sure that external examiners are aware that a student has CVD and that graphs, etc, need to take this into account.

For all ages

• Bright, low, inside or natural light can affect colour recognition. The brighter the light the easier it is to recognise colour. Seat children with CVD in good natural light and square on to the board, but try to avoid glare.
• Assign a classmate to help the child where coloured diagrams or pictures are being used.
• Check worksheets for colour issues and where possible use patterns or secondary indicators, ie labels, to differentiate, rather than colour. Photocopy worksheets into black and white then check that they still perform the task you require.
• Instead of simple coloured ‘traffic light’ coding systems, include patterning.
• Use strong contrast on the board and on computer screens. Do not use red and green or pastel colours to highlight different teaching points.
• Check computer settings, web pages and computer-based teaching aids with pupils to ensure they can pick out all of the relevant information.
• 'Audit’ your classroom to ensure important messages for the children are not indicated in difficult colours, especially red.
• Check the child has coloured pencils and paints, etc, marked with the colour of the pencil, but note some names like ‘termillion’ do not give colour clues.
• In games/PE check the child can see which children are in their team and also that they can see the ball, eg, red cricket balls and orange hockey balls are difficult to see against grass, particularly in poor light.
• Look out for other children teasing colour blind children for using incorrect colours and ensure any self-esteem issues are dealt with immediately.
• There are some careers that a student with CVD will not be able to undertake (ie, commercial pilot, some electrical trades), so early careers advice may be useful for these students.

Further information

For more information see the UK-based colourblindawareness(external link) website 

This information sheet originally written for UK teachers by Colour Blind Awareness was adapted by the Ministry of Health for the New Zealand context with their consent.