Colour blindness

What is colour blindness?

Colour blindness is a condition where you can’t see certain colours in the usual way. Colour blindness does not cause any blindness or lack of vision. People who are colour blind will confuse some colours and they will not see some colours as brightly as people with normal vision.

The condition is usually inherited and is present from birth. However, it can also happen later in life from damage to the brain or eyes.

What are the different types of colour blindness?

There are 3 main types of colour blindness.

Red-green colour blindness (deuteranopia and protanopia)

Red-green colour blindness is the most common form of colour blindness. It is usually inherited and mostly affects males. If you have red-green colour blindness, you will find it hard to tell reds from greens.

Blue-yellow colour blindness (tritanopia)

Blue-yellow colour blindness is less common than red-green colour blindness and affects only about 1 in 20 people with colour blindness. If you have blue-yellow colour blindness, you will find it hard to tell blues from yellows. It affects both males and females.

Complete colour blindness (monochromatism)

If you have this, you don’t see colour at all. Complete colour blindness is extremely rare.

How is colour blindness diagnosed?

Your doctor or optometrist can check you for colour blindness using different kinds of colour vision tests. The most common way is by using the Ishihara test. The test uses 38 specially designed cards. These cards have coloured dots in patterns with either a number or lines on it. When you see each card, you need to tell your doctor what number you see or how many lines your see. The test helps your doctor understand whether you have red-green colour blindness, and if so, to what degree.

Another newer test called the 100 Hue Test may provide your doctors with more detailed information about your colour blindness.

When should I see my doctor?

If you’re concerned about colour blindness, see an optometrist. Your doctor can also refer you to an ophthalmologist (eye specialist). They can recommend ways to manage colour blindness with tools such as special lenses or software.

If your ability to tell the difference between colours worsens over time, see an eye doctor as soon as possible. This may be a sign of an eye disease, such as macular degeneration, which can cause colour blindness.

How does colour blindness affect daily life?

Colour blindness might cause you some difficulties, but you can usually learn to overcome most of them.

For example, if you have red-green colour blindness, you might have trouble telling if red meat is cooked.

You might have trouble seeing the colours on traffic lights. But you can learn that the red is at the top and the green is at the bottom.

Children with colour blindness may need help with schoolwork, as educational materials are often colour-coded.

If you are colour blind, some occupations will be difficult. These include being a pilot, long distance driving or jobs where colours are important, such as graphic design.

Ask your doctor about how to best manage your particular type of colour blindness, and if special lenses or other tools can help you.