Colour Deficiency

About Colour Deficiency

Colour deficiency, commonly known as colour blindness, is the inability to perceive certain shades of colour. Red-green colour vision defects are the most common form of colour vision deficiency. It doesn’t mean that people with this condition can’t see these colours completely, however. Instead, it means they will have a more difficult time distinguishing between some shades of red, yellow, and green, depending on the lightness or darkness of the colour, or that they do not see a colour in the traditional way.

Woman looks at colourful paintings. Source: Pexels

Blue-yellow colour vision defects are another, much rarer, type of colour deficiency that cause problems with differentiating between shades of blue and green and between dark blue and black.

Despite the nickname for the condition, very few people are entirely colour blind.

Colour deficiency occurs because of issues with the photoreceptors in the retina of the eye, known as cones. Cones have pigments that recognise colours. When we see different colours, what we’re really perceiving is different wavelengths of light. Found in the central part of the retina (the macula) each cone is sensitive to either red, green, or blue light based on their wavelengths. Usually, pigments inside the cones register different colours and send that information through the optic nerve to the brain, which tells us which colour we’re seeing. But when cones don't have one or more of these light-sensitive pigments, they will be unable to determine the colour, causing colour deficiency.

Source: Shutterstock

In Australia, about 8% of males and 0.5% of females suffer colour deficiency to some degree.  While it’s good to know if you have the condition, colour deficiency rarely has a big impact on a person’s life.  Although, it may potentially affect your career prospects. Two examples are pilots and electricians – people in these professions need good colour vision to work safely, and you may be required to provide proof of good vision to work in these areas. People who work in art and graphic design also need to clearly detect colour variations.


Causes of Colour Deficiency

Colour deficiency is genetic. Most cases are inherited, and the condition is present throughout a person’s entire life.

There are a few other causes for colour deficiency. These are:

  • Vitamin A deficiency.
  • Damage to the areas of the brain where vision processing takes place.
  • Damage to the optic nerve or retina.
  • Some diseases. The degenerative eye diseases that can cause colour deficiency are glaucoma, diabetes, macular degeneration, and cataracts. The condition is also linked to Alzheimer's disease, Parkinson's disease, multiple sclerosis, chronic alcoholism, leukemia, and sickle cell anemia.
  • Some chemicals. Exposure with certain chemicals including fertilizers and styrene can cause loss of colour vision.
  • Medications for heart problems, high blood pressure, infections, nervous disorders and psychological problems.
  • It’s common for the ability to differentiate colours to gradually lessen as we get older.





Symptoms of Colour Deficiency

Colour deficiency is sometimes spotted when a child is around three or four years old and learning to tell the difference between colours and objects that are identified by their colour. Having difficulty identifying the correctly coloured object or toy is a sign that your child might be colour blind.

Father and child play with coloured blocks. Source: Pexels

Colour deficiency doesn’t always show symptoms however and it’s possible to live with the condition and not realise that you have it. Quite often, people with inherited red-green deficiency aren't aware of their problem because they do not know that others are perceiving a colour differently to them. For example, they are told that apples are red, and so they associate the colour they’re seeing with the word red, and do not realise that their “red” is different to the red that most people can see.

If your colour deficiency has developed in adulthood, you may notice a difference in the way colours appear to you.

Diagnosing Colour Deficiency

An optometrist can diagnose colour deficiency during a comprehensive eye examination. Specifically designed pictures formed of different colour dots, called pseudoisochromatic plates, are shown to a patient, who is asked to identify numbers made from the coloured dots. If you have regular colour vision, you’ll see the numbers. If you have a colour deficiency, you will not see them (or you will see a different number, depending on the design of the pseudoisochromatic plates).

Pseudoisochromatic plates. Source: Shutterstock

Pseudoisochromatic plates are a great way to initially diagnose colour blindness, but further tests may be required to find out what type of deficiency a patient has, and the severity of the deficiency. An optometrist can advise you on further testing.


Treating Colour Deficiency

Unfortunately, there is no cure or treatment available for colour deficiency. Tinted glasses and contact lenses can increase some people's ability to differentiate between colours but may compromise the ability to see other colours. Nothing can make them truly see the deficient colour.

If colour deficiency is caused by an illness or injury, treating the specific condition may increase colour perception.

While it can be frustrating sometimes, colour deficiency rarely causes too many issues for most people with the condition. Where it does affect your day-to-day life, one strategy to cope is using order rather than colour to navigate the world around you. For example, if somebody cannot differentiate between the colours of traffic lights, they can remember that red is on top, yellow in the middle and green on the bottom.

Green traffic light. Source: Unsplash

Commonly asked Colour Deficiency questions

How will I know if I have colour deficiency?

Some people know that they have a colour deficiency because they have had trouble distinguishing between different coloured things, or they have been diagnosed by an optometrist. It’s also possible to live with a colour deficiency and not know that you have it, as it hasn’t impacted your life. By visiting an optometrist for an eye examination, you can find out if you are colour blind.


Why is colour deficiency more common in males?

Colour deficiency is an inherited condition caused by a common X-linked recessive gene, passed from a mother to her son. If a female inherits one normal colour vision gene and one mutated gene, it’s very likely she won’t have a colour deficiency, because it’s a recessive trait. Since boys have only one X chromosome, their chance of inheriting a colour deficiency is much greater.

Females can also have a genetic colour deficiency, however this occurs less often – about 8% of white males are born with some degree of colour deficiency, whereas only 0.5% of females are born with colour vision deficiency.


Does having colour deficiency mean you’re more likely to get other eye conditions?

Having a genetic colour deficiency does not mean you’re more likely to have other, more significant problems with your eyes. Colour blindness is not associated with, and should not be confused for, regular blindness. People with red-green colour deficiency, the most common type, may have vision that is slightly less sharp than people with regular vision as cones within the retina help us to see fine detail as well as colour, and colour deficiency occurs when cones don’t have the right number of pigments.


Are there some jobs you can’t do if you have colour deficiency?

Having a severe colour deficiency may potentially affect your career prospects. Two examples are pilots and electricians – people in these professions need good colour vision to work safely, and you may be required to provide proof of good vision to work in these areas. People who work in art and graphic design also need to clearly detect colour variations.

Two pilots flying an airplane. Source: Pexels

Where can I go for more advice on colour deficiency?

We recommend making an appointment with an optometrist for a comprehensive eye examination. Comprehensive eye examinations, at regular intervals starting from childhood, ensure that most eye conditions can be identified. Eye examinations can also be an important tool for determining your overall health.

Published date: 10 November 2022


Author: Sophie Koh, National Professional Services Adviser at Optometry Australia

Bio: Sophie Koh is an experienced optometrist who started her career in the Northern Territory. She has broad experience working in public health and corporate settings across metropolitan, rural and outback Australia. She has extensive experience working in ophthalmology teams and training nurses in East Timor, Papua New Guinea and Solomon Islands. Sophie studied her undergraduate degree at the University of Melbourne and was amongst the first cohort of graduates to achieve the ACO Certificate in Ocular Therapeutics. She is currently the National Professional Services Adviser at Optometry Australia. She is passionate about public health and Indigenous eye health. She is devoted to empowering students and colleagues to improve their knowledge and skills so they can play a wider role in improving the health and wellbeing of our underprivileged communities locally and overseas.


Disclaimer: No information provided on the Good vision for life website is intended to constitute or substitute advice from visiting an optometrist. Many factors unknown to us may affect the applicability of any information on this website. You should seek appropriate personalised advice from a qualified optometrist about any eye health and vision conditions.