Colour blindness

What is colour blindness?

This is dyschromatopsia, a disease that affects the way people perceive colours. Colour blindness is therefore an inherited disease characterised by a defect in the perception of colours. A colour-blind child will distinguish colours differently: they will not have the same definition of primary colours. People with this condition cannot differentiate between red and green. 

Basic colour vision depends on the proper functioning of our cones. The cone is a retinal cell responsible for capturing light. A normal retina has three populations of cones, each with a specific sensitivity to different colours. It is the combination of signals from these three types of cones that allows us to identify an infinite number of colours, and not to confuse them. When one of the three families of cones is deficient, colour vision is impaired: this is colour blindness. 

What are signs of colour blindness in children?

Have you noticed that your child tends to confuse colours when you ask them to dress, for example? It is possible that they are colour-blind. People with colour blindness confuse pairs of colours. In principle, the child does not perceive the colour red and tends to confuse it with green. But if one of the colours is a little different, a little more red or a little more green, in slightly different shades, the colour-blind person will not confuse the colours. Confusion between blue and yellow may also be present.

Most of the time, the child does not spontaneously realise that they have a visual anomaly. Apart from impaired colour perception, their vision is normal. Either colour blindness is discovered by means of a colour vision test, or those around the child notice that colour recognition is not accurate. This colour dysfunction is often naturally detected at school through drawings and various activities involving colour schemes, and by parents at home with the choice of clothes.

How can colour blindness be screened for in children?

The Ishihara test is the simplest and most often used. The Ishihara test is a chromatic examination that will make it possible to evaluate the perception of colours. It was conceived in 1917 by Japanese teacher Shinobu Ishihara. If colour blindness is suspected in children, this diagnosis can be made by your ophthalmologist. They will present the 38 plates one after the other to the child who will have to indicate the shape or the number that they see or otherwise. 

As a result of this screening test, it will be possible to diagnose whether the child is colour-blind.

What are the treatments for colour blindness?

Colour blindness is not a disease or a disability, because it does not cause any specific problems with visual functions. Colour-blind children live very well with this deficiency and they do not feel any discomfort. The child will simply grow up with their own vision of colours. Today, there is no treatment to rectify this vision disorder. 

We advise you to inform your child’s teachers. A medical certificate attesting to the diagnosis, provided by your ophthalmologist, will allow the teaching staff to understand that it is impossible for the child to distinguish certain colours. It is important not to put the pupil in a situation of failure during sequences involving colours. 

Some professions require good colour vision. In his adult life, for example, it will be difficult for him to become an electrician, a soldier or an airline pilot. At this point, however, they will be able to carry out a more specific test in order to be assessed at a professional level.

What are the risk factors?

The only risk factor is the presence of a mutation on the X chromosome. Genetic transmission is maternal and colour blindness is mainly expressed in boys. A girl develops it only if she has received it from her father and mother.

What is the prevalence?

In Europe, 8% of boys and less than 0.5% of girls have some form of colour blindness.

What is the clinical course of colour blindness?

Colour blindness is a congenital, non-evolving condition. The visual function will remain unchanged throughout the life of the colour-blind person.

Find out more about children's visual disorders

Do you want to learn more about a particular visual condition? Discover our pages on myopia, congenital glaucoma, and astigmatism. We explain these visual disorders and tell you how to treat them to preserve your children’s visual acuity.