Colour blindness or colour vision deficiency is an eye condition in which an individual sees colours differently from others. According to Colour Blind Awareness Org., approximately 4.5% of the whole UK population is affected by the colour blindness and most of them are men. Colour blindness is typically genetic, but it can also occur at any age, either in the absence of cones or when the cones are non-functional.
The cones are photoreceptor cells in the retina of your eyes that help you see colours and distinguish between them. There are three types of cones, including:
- L-cones for sensing red
- M-cones for sensing green
- S-cones for sensing blue
Red and green are the colours most people find difficult to distinguish between, while yellow and blue are rare cases.
Types of Colour Blindness
Based on the non-functionality or absence of cones, there are also three types of colour blindness, such as:
Red-green Colour Blindness
This colour blindness is very common and occurs when the red and green cone cells are missing or are not working properly, making it difficult to differentiate between red and green colours. The condition is also known as ‘daltonism’.
The subtypes include:
- Protanomaly: When all cones are functional except the red ones, people experience decreased sensitivity to red light, making red, orange and yellow colours look less bright and muted.
- Protanopia: While protanomaly is a mild form of red-green colour deficiency, protanopia is a severe form in which people with this eye condition have red cones missing in their retinas. These people see red in shades of grey and often perceive green as yellow.
- Deuteranomaly: Deuteranomaly is when the green cones in the retina detect too much red light instead of green light, making green, red, yellow and brown appear the same or muted. While some people may see green as red or brownish, others may find it difficult to distinguish between purple and blue colours.
- Deuteranopia: Caused by the absence of green cones, this eye condition has people confused between red, green and yellow colours, as they may perceive red as brownish and green as beige /yellow.
Blue-yellow Colour Blindness
This is a rare condition in which the blue cones are either missing or damaged due to diabetes, an eye injury, eye disease (such as glaucoma) or hereditary reasons. The subtypes include:
Tritanomaly: This is caused by abnormal functionality of blue cones. Those who are affected see blue as green and yellow as pink or orange.
Tritanopia: The absence of blue cones causes tritanopia, making it hard to see blue and yellow. The blue appears more like green and there is little or no perception of yellow.
Complete Colour Blindness
Also known as monochromacy, complete colour blindness is very rare. Those who are affected cannot see any other colours but different shades of white, black and grey. The subtypes are:
Blue Cone monochromacy (BCM): BCM is a genetic eye disorder in which the L and M cones are missing in the retina. The signs include severe colour blindness, low visual acuity, sensitivity to light and uncontrollable eye movements.
Rod monochromacy: This condition occurs when none of the cones in the retina function normally. Also called achromatopsia, it is a severe colour blindness. Those who are affected see the world in white, black and grey and their eyes are extremely sensitive to light.
Colour Blindness Tests
There are two types of colour blindness tests, including:
Ishihara test: It is the most commonly used test, which involves a screening technique to detect red-green colour deficiency. The test is conducted using a series of Ishihara plates, featuring coloured dots in different shapes and sizes. Within the dotted pattern, there are some dots that form either a number or a shape. While these shapes or numbers are visible to people with normal vision, those with red-green colour deficiency cannot see them.
Colour arrangement test: This test involves arranging coloured chips or tiles closest to their shades. It helps identify the type and severity of colour blindness by analysing how those with colour blindness arrange colours.
Treatment of Colour Blindness
As of now, there is no cure for genetic colour blindness. However, available treatments are more focused on helping individuals manage the eye condition.
There are also other options available to help with colour vision deficiency, including:
Colour blindness glasses: These are specialised glasses for those with a mild form of red-green colour blindness. Although these glasses do not provide a complete corrective solution, they help improve the wearer’s ability to distinguish between shades. Popular brands that make colour blindness glasses include ColorCorrection System, EnChroma, Pilestone and VINO Optics.
”Please note that these glasses shouldn’t be worn without consulting your optician.”
Visual aid apps: Certain mobile applications and AI technology can help people click photos and distinguish colours in real-time. Users can either point their camera at various objects to get instant identification of the colour or tap the photo to identify the colour.
Frequently Asked Questions
Is colour blindness permanent?
Yes, this condition is permanent unless the colour deficiency is caused by an eye condition or the use of certain medication.
What famous people have colour blindness?
Several famous people, including Prince William, Mark Zuckerberg, Keanu Reeves and Eddie Redmayne have colour blindness.
What jobs to avoid with colour blindness?
People with colour blindness should avoid aviation and transportation fields, marine and armed forces, emergency services, and plumbing and electrical engineering roles.
Disclaimer: The advice in this article is for informational purposes only and does not replace medical care or an in-person check-up. Please check with an eyecare professional before purchasing any products or remedies. For information on our article review process, please refer to our Editorial Policy.
Khuram Sarwar is a qualified Dispensing Optician at Feel Good Contacts. He holds over 14 years of experience in the optical industry. Registered with the General Optical Council (GOC), Mr. Sarwar is also a member of the Association of British Dispensing Opticians (ABDO). He completed his training at ABDO College before achieving a BSc (Hons) in Ophthalmic Dispensing from Canterbury Christ Church University. In his professional career, Khuram has worked with some of the industry’s leading experts and continues to offer practical, expert advice on both contact lenses and glasses.
