Colour Deficiency

Colour deficiency occurs when your ability to distinguish colours and shades is different than normal.

What is colour deficiency? 

Colour deficiency occurs when your ability to distinguish colours and shades is different than normal. The term colour blindness is often used, but usually incorrectly. Only a very small number of people are completely unable to identify any colours, a condition called achromatopsia. Colour deficiency is more common in males than females, with one in 10 males having a colour deficiency.

What causes colour deficiency? 

Colour deficiency is usually an inherited condition, passed from mother to son, but it can also result from certain diseases, trauma or as a side effect of certain medications. Colour deficiency is the result of an imbalance found in the three cones of the retina, allowing us to perceive colour.

What types of colour deficiency exist? 

There are three types of colour deficiency: two different kinds of red-green deficiency and one called blue-yellow deficiency.

The red-green deficiencies 

These are the most common and are usually inherited, resulting in the inability to distinguish between certain shades of
• Reds, browns, pinks and oranges
• Greens and blues

Blue-yellow deficiencies 

These are rare and usually acquired from optic nerve damage. This results in the inability to distinguish between certain shades of blue and yellow.

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

How is colour deficiency detected?

Children who are colour deficient are generally unaware of their condition. They assume that everyone sees things the same way. As a result, a complete optometric examination, including a test for colour vision, is recommended for every child.

The test for colour deficiency is a relatively simple one. It involves a series of coloured plates with a number or designs. The plates have been created in such a way that a person with normal colour vision can see certain figures in the designs. A person with a colour deficiency will either see a different number of designs or will be unable to distinguish the figures.

When should a person be tested for colour deficiency?
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, such as pilots, electricians, some military personnel, police officers and others.

Can colour deficiency be cured?

Unfortunately, a cure for colour deficiency has not 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.

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