Colour deficiency occurs when your ability to distinguish colours and shades is different or less than normal. Only a very small number of people are completely unable to identify any colours (colour blind). Colour deficiency is more common in men than in women, with one in 10 men having a colour deficiency.

What causes colour deficiency?

Colour deficiency is usually inherited, but can also result from certain diseases, trauma, or as a side effect of certain medications. Colour deficiency is the result of an imbalance in the three kinds of cones in the retina that allow us to perceive colour.

How is colour deficiency detected?

Children who are colour deficient are generally unaware of their condition. They assume that everyone sees things the way they do. Every child should be checked for colour deficiency by at least age five. It is important to detect colour deficiency early because colour coded learning materials are used extensively in the primary grades.

In addition, colour deficiency may affect the career path of an individual, since the ability to distinguish colours is an important aspect of some jobs. Unfortunately a cure for colour deficiency has not yet been discovered. However, a person with colour deficiency can be taught to adapt to the inability to distinguish colours.

 

What types of colour deficiency exist?

There are three types of colour deficiency:

• two different kinds of red-green deficiency
  The red-green deficiencies are by far the most common and are usually inherited, resulting in the inability to distinguish between certain shades of reds, browns, pinks and oranges, or greens and blues.
• one type of blue-yellow deficiency
  Blue-yellow deficiency is very rare and is usually acquired secondary to damage to the optic nerve and results in the inability to distinguish between certain shades of blue, as well as shades of yellow.

People with complete colour blindness see objects in shades of black, white and grey.

Can colour deficiency be cured?

Unfortunately, a cure for colour deficiency has not yet been discovered. A person with a colour deficiency can, however, be taught proper colour naming and to accurately distinguish colours. For example, you can be taught to recognize the brightness and location of a traffic light rather than the colour itself.

It is sometimes possible to increase the ability to distinguish colours with the use of special filters. For example, a special red tinted contact lens can be used in one eye, to aid people with certain colour deficiencies.