Colour vision deficiency - Diagnosing colour vision deficiency

Many people become aware they have colour vision deficiency when they're unable to identify colours correctly.

Your child may have difficulty naming colours or you may struggle to read a coloured map or document.

For example, reds, oranges, yellows, browns and greens may all appear to be a similar colour to someone with colour vision deficiency.

Sometimes mild colour vision deficiencies may go undetected. For example, a child who has inherited the condition may be unaware that they have a problem distinguishing between different colours.

It's very important to identify colour vision deficiency early because a child's learning experience relies heavily on the use of colour.

Colour vision tests

It's important to be aware that colour vision tests don't form part of the standard NHS eye test. Many opticians don't carry them out unless they're specifically asked to do so.

You could therefore have colour vision deficiency but be unaware that you're having problems perceiving colour.

This can lead to problems – for example, a school leaver may suddenly find that they can't pursue a certain career because they have colour vision deficiency.

You may need to ask your optician to carry out a colour vision test for you.

There are several different tests for checking colour vision. Two of the tests you may have are described below.

Ishihara test

The Ishihara test is the most commonly used test for checking colour vision. It can only screen for red/green deficiencies. Specialist tests are needed to diagnose blue/yellow colour vision deficiency.

The Ishihara test uses plates made up of multicoloured dots. Some of the dots will be a different colour and depict a number.

You'll be asked to look at the plate and say if you see a number. A note will be taken of numbers you have difficulty identifying or you identify incorrectly.

You may have a colour vision deficiency if you have problems completing the Ishihara plate test.

Arrangement test

The arrangement test is where you arrange coloured objects in order of their different shades of colour.

For example, you may be given coloured blocks of slightly differing shades and be asked to arrange them from one shade to another.

A particular pattern of mistakes could indicate that you have a colour vision deficiency.


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