Colour vision deficiency 


People with colour vision deficiency often find it difficult to distinguish between two different colours  

How common is colour vision deficiency?

Inherited colour vision deficiency affects more men than women, with around 8% of men and 0.5% of women being affected.

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People with colour vision deficiency are unable to see colours clearly and accurately. They may find it difficult to distinguish between different colours.

Colour vision deficiency is often referred to as colour blindness. However, true colour blindness, where no colour can be seen at all, is rare.

People with colour vision deficiency may have difficulty identifying pale colours or deep colours if the lighting is poor.

Colour vision deficiency can vary in severity. Some people are unaware they have a colour deficiency until they have a colour vision test. Others will experience a very slight difference in the way they appreciate different hues and shades of colour. In rare cases, a person may experience many colours that all appear to be the same.

Read more about the symptoms of colour vision deficiency.

Types of colour vision deficiency

There are two main types of colour vision deficiency:

  • red-green deficiency – where people are unable to distinguish certain shades of red and green; it is the most commonly inherited type
  • blue-yellow deficiency – this is a rare condition where it is difficult to distinguish between blue and green, and yellow may appear as a pale grey or purple

What causes colour vision deficiency?

In most cases, colour vision deficiency is an inherited condition (passed on from your parents). However, it can also sometimes develop as a result of a pre-existing health condition or as a side effect of a medicine.

Inherited colour vision deficiency occurs due to an abnormality in the retina (the film that lines the back of the eye). The retina is made of rod and cone cells. There are three main types of cone cells. In people with inherited colour deficiency, one type of cone cell is missing or does not function normally. 

Read more about the causes of colour vision deficiency.

Recognising colour vision deficiency

Many people first become aware they have a colour vision deficiency when they have a problem identifying colours correctly.

For example, a child may have difficulty naming colours or you may struggle to read a map or a document.

It is important to identify a colour vision problem early. If your child is diagnosed at an early age and teachers are made aware, their learning experience can be adapted.

Read more about diagnosing colour vision deficiency.

Treating colour vision deficiency

There is currently no cure for inherited colour vision deficiency because it is not possible to repair or replace the cone cells in the retina.

However, as colour vision deficiency does not cause any long-term health problems, treatment is not essential for you to be able to lead a normal, healthy life.

If you have colour vision deficiency as a result of a pre-existing health condition, or from taking a certain type of medication, it may be possible to improve your symptoms, either by treating the underlying condition or by using an alternative medication.

Most people with colour vision deficiency learn to adapt to their condition, and it is usually possible to find ways to compensate for your difficulty with colours. For example, it is possible to recognise the position of the lights on a traffic light, rather than the different colours.

Read more about treating colour vision deficiency.


In most cases, people with colour vision deficiency are unlikely to have long-term health problems.

However, if you have a red-green colour deficiency, it may be difficult for you to spot blood in body fluids, which can sometimes be an early sign of other medical conditions.

Having colour vision deficiency could also affect your career choice. This is because certain jobs, such as pilots and air traffic controllers, require accurate colour recognition.

If your child has colour vision deficiency, they may struggle at school unless the teacher is made aware of the problem. Many learning materials are colour coded and your child may find it more difficult if their learning environment is not adapted to their specific needs.

Read more about the complications of colour vision deficiency.

Page last reviewed: 02/04/2012

Next review due: 02/04/2014


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