Colour vision deficiency (colour blindness)
Colour blindness is when you see colours differently from most people and have difficulty telling colours apart. There's no treatment for colour vision deficiency that runs in families, but people usually adapt to living with it.
What causes colour blindness?
We see colour using specialised cells at the back of the eye called cones, which are located in the retina. There are three types of cones, each sensitive to different wavelengths of light associated with red, green and blue.
Colour blindness occurs when one or more of these cone types are missing, not functioning normally, or have been damaged. As a result, some colours may be difficult to distinguish or may look different from how they appear to people with typical colour vision.
Most colour blindness is inherited and passed down through families.
However, colour vision problems can also develop later in life as a result of:
- Age-related macular degeneration
- Glaucoma
- Diabetic eye disease
- Optic nerve disorders
- Certain medications
- Vitamin deficiencies
- Brain or eye injuries
If you notice a sudden change in your colour vision, have your eyes examined, as this may indicate an underlying health condition.
Are there different forms?
Yes.
Red-green colour blindness
This is the most common type. People with red-green colour blindness may have difficulty distinguishing between reds, greens, browns and some shades of orange.
Blue-yellow colour blindness
This less common form makes it difficult to distinguish between some blues, greens, yellows and purples.
Complete colour blindness (achromatopsia)
This extremely rare condition causes a person to see very little or no colour at all. People with achromatopsia often also experience light sensitivity and reduced visual acuity.
Could my child have colour blindness?
Many children with colour blindness do not realise they see colours differently because they have always seen the world that way.
Signs that your child may have colour blindness include:
- Difficulty learning colour names
- Confusing colours that look similar
- Trouble sorting objects by colour
- Difficulty interpreting colour-coded learning materials
- A family history of colour blindness
Colour blindness can often be identified in preschool or primary school years. If you are concerned, speak with your optometrist or GP, who may recommend further assessment by an ophthalmologist.
Early diagnosis can help children develop strategies for learning and navigating colour-coded information both at school and in everyday life.
Is colour blindness a problem and can it be corrected?
Colour blindness is not a disease. For most people, it is simply a different way of seeing colour.
Inherited colour blindness cannot currently be cured. However, most people adapt well and develop practical strategies to manage everyday tasks.
For example, people may learn to identify traffic lights by their position rather than relying solely on colour. Smartphone apps and accessibility features can also help identify colours and interpret colour-coded information.
Many people with colour blindness lead lives without significant limitations. However, certain occupations may have colour vision requirements for safety reasons, including some roles in:
- Aviation
- Maritime transport
- Defence
- Emergency services
- Electrical trades
- Rail operations
Requirements vary by profession and the severity of the colour vision deficiency.
Can colour-blind people drive?
Yes. Most people with colour blindness can hold a standard driver's licence in Australia.
Drivers generally learn to recognise traffic lights by their position and brightness as well as their colour. Some occupations involving commercial transport may have additional colour vision requirements.
What is the best test for colour blindness?
No single test is best for everyone. Different tests provide different types of information.
Developed 100 years ago, the Ishihara Test is still the best test to see if you have the condition. A more recent test, the 100-Hue Test or Colour Hue Test, can provide more detailed information. There are online versions of both tests, which you can try, but for a variety of reasons they aren't considered strong enough (computer colours vary, for example).
Because colour blindness affects individuals in different ways, eye specialists now have a range of further tests and equipment they can use, including the RGB anomaloscope.
If you are concerned about colour blindness, you should see an ophthalmologist or optometrist. Some school health services also offer the test, or you can ask your optometrist next time you’re having your regular eye check-up.
Ishihara Plate No. 1 (Number 12). Used to for the en:Ishihata test of color blindness.
Farnsworth Munsell 100 Hue Colour Blindness Test
Frequently Asked Questions
Is colour blindness inherited?
In most cases, yes. The most common forms of colour blindness are inherited and passed down through families.
Can girls be colour blind?
Yes, although it is much less common. Colour blindness affects men more frequently because of the way the genes responsible for many forms of colour vision deficiency are inherited.
Can colour blindness get worse with age?
Inherited colour blindness generally remains stable throughout life. However, colour vision can change with age due to eye diseases or other health conditions.
Can colour blindness develop later in life?
Yes. Conditions affecting the retina, optic nerve or brain can sometimes cause acquired colour vision deficiency.
Can colour blindness be cured?
There is currently no cure for inherited colour blindness. However, many people manage the condition effectively using coping strategies and assistive technologies.
Maintaining healthy vision
While inherited colour blindness cannot be prevented, regular eye examinations help detect eye diseases that can affect colour vision and overall sight.
Sydney Eye Hospital clinicians diagnose and treat a wide range of eye conditions, including glaucoma, macular degeneration and diabetic eye disease. Early detection remains one of the most important ways to protect your vision and eye health throughout life.
