Help and frequently asked questions

How can colour vision be tested?


There are various tests, but the most commonly used is the Ishihara test.

In this the optician shows the patient a number of plates which are printed with different coloured dots of differing brightness, density and size, arranged so that the dots of similar colour form a figure (for example a number) among a background of dots in another colour.

If a person has defective colour vision they'll be unable to identify some or all of the figures hidden in the dots depending upon what type of colour blindness they suffer from.

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