Causes of colour blindness

In the retina, in the back of the eye, there are two types of cells that pick up light. Rod cells see things at night, but don’t pick up colours. Cone cells pick up brighter light, and see details and differences between colours.

There are three types of cone cells. Each type picks up a different colour – red, green and blue. In a person who is colour blind, only two out of three of these types of cone cells work normally.

Children usually inherit colour blindness from either their mother, father or both parents.

Red-green colour blindness is the most common type. It happens in 8% of boys and 0.4% of girls. Blue colour blindness happens in only 5% of cases of colour blindness. It happens equally in boys and girls.

Symptoms of colour blindness

Children with colour blindness see colours in a different way from normal. They often see two different colours as  the same. The colours they see as the same are mostly green and red.

Although colour-blind children confuse some colours, their vision should be clear for close work and when looking in the distance.

If your child has colour blindness, he might have trouble correctly identifying some colours after about the age of four. Also, he might struggle to separate things according to colour. This might be obvious at preschool or school, especially with activities like sorting blocks, colouring or copying different coloured text.

Colour blindness is stable and doesn’t get worse or better over time.

Treatment for colour blindness

If you think your child might be colour blind, your doctor can organise special tests. If there are other people in the family with colour blindness, you should have your sons tested.

There’s no cure for colour blindness. But it isn’t a serious condition, because children learn colours by association.

It’s a good idea to let your child’s teachers know that your child has colour vision problems, so the teachers can choose teaching activities that don’t involve spotting colour differences.

As your child gets older, it might be unsafe or hard for her to do jobs where colour identification is important.