What is colour blindness?

Colour blindness is a condition where you can't see certain colours the way most people do. Colour blindness is not the same as blindness or lack of vision. People who are colour blind will confuse some colours. They may not see some colours as brightly as people with normal vision.

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

Colour blindness is also known as 'colour vision deficiency'.

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 (monochromacy)

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

What are the symptoms of colour blindness?

People who are colour blind will:

• confuse some colours such as greens, yellows, oranges and reds
• not see some colours as brightly as people with normal vision

Colour blindness symptoms can start to show in children around the age of 4 years. It is often around this age they find it hard to recognise or name some colours.

What causes colour blindness?

Colour blindness happens mainly when the cones (special cells in the retina that detect colour) are missing or not working properly.

Most colour vision problems are genetic and people with colour blindness will be affected from birth. There are also other causes that are less common, such as:

• shaken baby syndrome, accidents and other traumas that cause swelling of the brain or damage to the retina
• vitamin A deficiency
• eye diseases such as macular degeneration, glaucoma, cataracts or retinal damage from diabetes

When should I see my doctor?

If you're worried about colour blindness for yourself or your child, 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 child is more than 4 years old and seems to have trouble recognising colours, such as sorting objects by colour, talk to your doctor, optometrist or community health nurse.

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 is colour blindness diagnosed?

Your optometrist or ophthalmologist can check for colour blindness using different kinds of colour vision tests.

The Ishihara test is the most well-known test for diagnosing colour blindness. It uses 38 specially designed cards, which have coloured dots in patterns that show a number or lines. Your doctor will ask what number or how many lines your see. The test helps your doctor assess whether you have red-green colour blindness, and the severity of the condition.

Another test called the 100 Hue Test or Colour Hue Test may provide your doctor with more detailed information about your colour blindness.

It can be difficult to diagnose colour blindness in children. This is because colour blindness is often mild and can go unnoticed until a child is learning the difference between colours and recognises objects based on their colours. If you are worried or think your child may be colour blind, speak with your doctor or an optometrist.

How is colour blindness treated?

There is no treatment or cure for colour blindness. Optometrists can provide tinted lenses for one eye. This may help with detecting some colours but can make it harder to see others.

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

Living with colour blindness

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, it might be hard for you to see colours on traffic lights. But you can learn that the red is at the top and the green is at the bottom.

If you are colour blind, some jobs will be more difficult. These include being a pilot, professional driver, graphic designer or electrician.

If your child is colour blind they may need help with schoolwork, as educational materials are often colour-coded.

What are the complications of colour blindness?

Colour blindness can affect children's learning in school where items may be colour coded. It can also limit career choices, as some jobs need good colour vision including:

• police
• pilots
• electricians
• heavy vehicle drivers
• designers

Can colour blindness be prevented?

The main cause of colour blindness is genetic and can't be prevented. Some types colour blindness is caused by disease, accidents or vitamin A deficiency.

Read more on eye care and how to prevent eye injury and illness.

Read more on vitamin A and your health.

Resources and support

Visit Vision Australia for a range of resources for people with vision problems.

Read the Digital NSW guide to digital accessibility for colour blind users.

HealthyWA has a factsheet on colour blindness, including tips on helping children who are colour blind.

For information and advice, you can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.