Ishihara test: what is colour blindness, and how can you get tested?

Not everyone sees the world the way you do. Find out more about colour blindness, its science and its effects.

Ishihara colour plates
(Image credit: SSPL/Science Museum)

Colour blindness affects approximately one in 12 men and one in 200 women, which equates to 4.5 per cent of the population or around 2.7 million people in the UK, according to campaign group Colour Blind Awareness.

Colour vision deficiency, or CVD, is usually genetic, passed to the child from the mother, but it can also develop as a by-product of aging or medical conditions, such as diabetes.

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