Colour is a big part of our lives. In a way, it shapes how we see the world, navigate our surroundings, and connect with people, places, and objects. But for some, colours don’t appear the way they do for most people. This condition is known as colour blindness.
Because of its name, we think people with colour blindness see the world in black and white. But that’s not the case. Instead, they have difficulty distinguishing between certain colours.
This blog will explain what colour blindness is, its different types, what causes it, and how an eye exam can diagnose it.
What is colour Blindness?
Colour blindness, also called colour vision deficiency, is an eye condition where a person has trouble seeing certain colours correctly. It happens when the light-sensitive cells in the eye, called cones, don’t work as they should. These cones help us see colours by detecting red, green, and blue light. When one or more of these cones don’t function properly, the brain struggles to distinguish certain colours.
The way colour perception is affected can sometimes overlap with other vision issues, which is why understanding common eye problems and their treatments can provide a broader picture.
How the Eye Normally Sees Colour
The human eye contains three types of cone cells in the retina:
- Red cones (detect red light)
- Green cones (detect green light)
- Blue cones (detect blue light)
Each cone responds to different wavelengths of light, and together, they allow us to see a full spectrum of colours. If one type of cone is missing or not working properly, colour vision is affected.
How Common is Colour Blindness?
Colour blindness is much more common in men than in women. About 1 in 12 men and 1 in 200 women have some form of colour blindness. This is because most types of colour blindness are inherited and linked to the X chromosome. Since men have only one X chromosome, they are more likely to inherit the condition. Women, on the other hand, have two X chromosomes, which makes it less likely for both to carry the gene for colour blindness.
Types of Colour Blindness
Not all cases of colour blindness are the same. Some people have mild difficulty distinguishing certain shades, while others have more severe colour vision problems. In rare cases, a person may not see any colour at all. There are three main types of colour blindness:
1. Red-Green Colour Blindness (Most Common Type)
People with red-green colour blindness have trouble distinguishing between reds and greens. This happens when the red or green cone cells in the eye don’t work properly.
There are two subtypes:
- Protanomaly – The red cones don’t detect enough red light, making red appear dull or brownish.
- Deuteranomaly – The green cones don’t detect enough green light, making greens and reds look similar.
This type is the most common form of colour blindness and is usually inherited.
2. Blue-Yellow Colour Blindness (Less Common)
This type affects how a person sees blues and yellows. It happens when the blue cone cells are faulty or missing.
There are two subtypes:
- Tritanomaly – The blue cones don’t detect enough blue light, making blue look more like green, and yellow may appear pinkish.
- Tritanopia – The person lacks blue cones completely, so they cannot see blue and struggle to differentiate between blue and green or yellow and pink.
Unlike red-green colour blindness, blue-yellow colour blindness is not linked to gender and can affect both men and women equally.
3. Total colour Blindness (Rare)
In very rare cases, a person cannot see any colour at all. This condition is called monochromacy or achromatopsia. People with this condition see the world in black, white, and shades of grey.
They may also have poor vision in bright light because their eyes are extra sensitive to light.
Causes of Colour Blindness
Colour blindness can be genetic (inherited from parents) or acquired (caused by injury, disease, or medication).
1. Genetic Colour Blindness (Inherited from Family)
Most cases of colour blindness are passed down from parents. If a person is born with faulty cone cells, their colour vision will always be affected.
- The gene for red-green colour blindness is located on the X chromosome, which is why men are affected more often.
- Blue-yellow colour blindness is less common and not linked to the X chromosome, so men and women are equally affected.
- If a child inherits one normal X chromosome and one affected X chromosome, they will have normal colour vision. But if both X chromosomes carry the faulty gene, they will be colour blind.
There is no cure for genetic colour blindness because it is part of a person’s DNA.
2. Acquired colour Blindness (Caused by Other Factors)
Some people develop colour blindness later in life due to:
- Eye Diseases – Conditions like glaucoma, macular degeneration, and diabetic retinopathy can damage the retina and affect colour vision.
- Brain or Nerve Damage – A stroke, head injury, or brain tumour can interfere with how the brain processes colour.
- Certain Medications – Some drugs, like those used for heart conditions, malaria, or mental health disorders, can cause colour vision problems.
- Ageing – As people get older, the lens of the eye becomes yellowish, which affects how they see colours.
Unlike genetic colour blindness, acquired colour blindness may improve if the underlying cause is treated.
Common Tests for Colour Blindness
If you suspect you have colour blindness or struggle to see certain colours, an eye exam can confirm it. Eye doctors use simple but effective tests to check for colour vision deficiencies.
1. Ishihara Test (Most Common Test for Red-Green Colour Blindness)
The Ishihara test is the most well-known test for colour blindness. It consists of a series of circular plates (Ishihara plates) filled with coloured dots. These dots form numbers or shapes that people with normal colour vision can easily see.
- If you can see the numbers, your colour vision is normal.
- If you cannot see the numbers or see a different number, you may have red-green colour blindness.
This test is quick and easy, but mainly detects red-green colour blindness. It does not test for blue-yellow deficiencies or total colour blindness.
2. Farnsworth D-15 Test (For More Detailed Colour Deficiency Testing)
The Farnsworth D-15 test involves arranging a series of coloured caps or tiles in order of shade. People with normal colour vision can easily arrange them in the correct sequence.
However, if someone has colour blindness, they will place the colours incorrectly in a way that matches their specific deficiency. This test helps doctors determine the type and severity of colour blindness.
3. Anomaloscope (Advanced Testing for Red-Green Colour Blindness)
An anomaloscope is a special device used to measure how well a person can distinguish between red and green shades.
- The person adjusts two light sources until they match in brightness and colour.
- If they cannot match them correctly, it indicates red-green colour blindness.
This test is more precise but is not commonly used in routine eye exams.
4. Cambridge colour Test (Computerized Colour Blindness Test)
This is a modern, computer-based test similar to the Ishihara test but more advanced. The person looks at a screen and identifies a shape hidden in a pattern of coloured dots. It helps detect all types of colour blindness.
To get an accurate diagnosis and guidance on managing colour vision deficiencies, it’s important to consult a professional. Finding a reliable Optometry Near Me ensures you receive comprehensive testing and personalised recommendations tailored to your visual needs.
Why Is It Important to Diagnose Colour Blindness?
Many people with colour blindness don’t realise they have it until they fail a vision test for a job or struggle with everyday tasks. Getting diagnosed helps in several ways:
- Career Choices – Some jobs, like pilots, electricians, and graphic designers, require normal colour vision. Knowing early can help in choosing the right career.
- Better Daily Life – People with colour blindness can use colour filters, apps, or special colour blindness glasses to help them differentiate colours more easily.
Understanding Personal Limitations – A diagnosis helps people avoid situations where colour vision is crucial, such as reading colour-coded charts or traffic signals.
Can Colour Blindness Be Treated?
Genetic colour blindness cannot be cured, but there are tools to help:
- Colour Blindness Glasses – These glasses use special lenses to enhance colour contrast, making it easier to distinguish colours.
- Colour-Adjusting Apps – Some smartphone apps alter screen colours to make them more distinguishable for colour-blind users.
- Training & Adaptation – People with colour blindness can learn to recognise colours by brightness or position (for example, knowing that the top traffic light is red and the bottom is green).
If colour blindness is acquired due to an illness, injury, or medication, treating the underlying cause may improve colour vision.
How Can 360 Eyecare Help?
At 360 Eyecare, we offer comprehensive colour vision testing to accurately diagnose colour blindness. Our Toronto optometrists provide personalised solutions, including colour-enhancing lenses, digital tools, and adaptation techniques to help patients navigate daily challenges.
We also guide individuals on workplace accommodations and career options for those affected by colour vision deficiencies. For children, we recommend classroom adjustments and visual aids. Additionally, our regular eye exams ensure overall eye health, detecting any underlying conditions. If you suspect colour blindness, book an appointment with us for evaluation and support.
Final Thoughts
Colour blindness is a lifelong condition for most people, but it doesn’t have to be a major obstacle. With proper diagnosis and the right tools, people with colour vision deficiencies can adapt and live normal, independent lives. If you suspect you have trouble seeing colours, a comprehensive eye exam can help determine the type and severity of your condition.
Frequently Asked Questions
- Can colour blindness be treated or cured?
Genetic colour blindness has no cure, but colour-enhancing glasses, digital tools, and adaptation techniques can help improve colour perception and daily function. Acquired colour blindness may improve if the underlying cause is treated.
- How do I know if I am color blind?
If you struggle to distinguish certain colours, an eye exam with colour vision tests like the Ishihara test or Farnsworth D-15 can confirm whether you have colour blindness and its severity.
- Can colour blindness affect my career options?
Yes, certain jobs like pilots, electricians, and graphic designers require normal colour vision. However, many careers accommodate color-blind individuals with tools and adaptations to perform tasks effectively.
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