Around 1 in 12 men and 1 in 200 women have some form of colour vision deficiency. Most people with it aren’t truly “colour blind.” They just find certain colours, usually reds and greens, hard to tell apart. Many don’t realise until a test or an awkward clothing choice reveals it.
Imagine a seven-year-old getting frustrated at school because he keeps colouring trees brown and tree trunks green, and can’t find the “red” pen. His teacher thinks he isn’t paying attention. A simple colour vision test shows he has red-green colour deficiency. Suddenly, a lot makes sense.
Causes
- Inherited: by far the most common cause, passed on through the X chromosome, which is why men are affected far more often
- Acquired: from eye diseases, diabetes, some medicines, or brain injury. A change in colour vision in adulthood should be checked.
Testing
Optometrists commonly use the Ishihara test, with numbers hidden in coloured dots. More detailed tests can identify the type and severity. There’s no cure for inherited colour deficiency, and special tinted glasses help some people distinguish colours but don’t restore normal colour vision.
But does it affect careers?
Some jobs, such as pilots, some electrical work and some armed forces roles, have colour vision standards. In healthcare, many people with colour deficiency work successfully, using strategies such as reading labels and numbers rather than relying on colour, and asking colleagues to double-check colour-coded results when needed. Check the rules for any career you’re considering.
Your next step: If your child struggles with colours at school, book an eye test and tell the optometrist. Then let the school know, so they can use labels and patterns as well as colours.
Sources: US National Eye Institute (Colour blindness), NHS (Colour vision deficiency), American Academy of Ophthalmology. This guide is for general information and does not replace advice from your own nurse, doctor or optometrist.
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