What is Colour Blindness? And How Does It Impact The Life Of Someone With It?
Updated: Jul 31, 2018
The way we experience life is principally determined by our senses. The functioning sensitivity of those senses can have a profound effect on the quality of our lives. Would food be so enjoyable if we could only taste half as well as we do? And would relaxing in sunshine be as effective if we couldn't feel the warmth of those rays? What about if you could only see certain colours, or none at all? There is a surprisingly large number of people with a sensory impairment few of us really understand, and it is called colour blindness.
Approximately 1 in 8 men and 1 in 200 women suffer from a colour blindness or colour-deficiency, meaning the chances are you probably know at least one person who has it. Statistics on colour blindness suggest that males of Caucasian descent (5.6%) are the most likely to suffer from it, followed by Asian males (3.1%) compared to other ethnicities.
Despite what many people mistakenly think, colour blindness is not about seeing in black and white. Although total colour blindness does exist in the form of achromatopsia, it is the rarest form of colour vision deficiency. People who can only see in black and white make up a mere 0.00003% of the world's population.
More than 99% of all colour blind people can actually see colors - just a narrower spectrum compared to somebody with normal colour vision.
The term "colour vision deficiency" (CVD) is considered to be more accurate, despite "colour blindness" being more commonly used.
What is the life of a colour blind person like?
It's easy to take perfect colour vision for granted until you meet someone who is colour blind or colour deficient. Although not as dramatic as other visual impairments, colour blind people can face daily challenges when undertaking simple tasks such as playing sports, selecting fruit and vegetables whilst shopping, and choosing what colour clothes to wear.
Despite knowing several people with colour vision deficiency, including Sensorama's own Oliver, I had never given much thought to the impact it had on their daily lives. Since those with colour blindness have grown up with it, they have several subtle strategies for dealing with everyday situations - from asking other people to help, to hazarding a guess based on previous experience and logic. However, dig a little deeper and it's easy to see the impact being colour blind can have.
A major frustration for colour blind people is to be laughed at for making a colour selection faux pas, as this is not a matter of incompetence or unwillingness to see the right colours. What’s more, it is difficult to explain what exactly they do see. Living an entire life without being able to see certain colours places limitations on a person's colour vocabulary. If you have never seen bright apple-red or rich teal-blue, then explaining those colours, or even the washed out hues you can see, is practically impossible.
For those colour blind people with the time and patience there are numerous helpful tools available to help find precise colour descriptions, such as Colbindor's Colour Name and Hue page. This sadly doesn't help to actually 'see' the colours, just find out where they are on a colour spectrum and use descriptions a person with normal vision would understand.
How colour blindness can limit career choices.
At its worst, colour blindness can cost a person their dream career. One of my friends mused that with perfectly functioning colour vision his life would have been very different. He grew up in the Air Cadets completely unaware of any problem until he decided to join the RAF. However he failed his medical exam in the most unexpected way: failing a colour blindness test. Without the ability to distinguish clearly between red and green, he could be a flying hazard, unable to tell the exact direction another aircraft was flying at night, or decipher the runway coding lights.
What exactly are the mechanics behind colour blindness?
Simply put, colour blindness is the decreased ability to see colour or differences in colour. It is caused by an inherited genetic fault in the colour sensing cones in the eye, for which there is currently no cure. In rare cases it can also result from physical or chemical damage to the eye, optic nerve, or parts of the brain.
The National Eye Institute USA succinctly summarises the mechanisms behind our colour vision:
Our vision begins when light enters the eye and the cornea and lens focus it onto the retina, a thin layer of tissue at the back of the eye. This 0.3mm diameter area contains millions of light-sensitive cells called photoreceptors. Some photoreceptors are shaped like rods and some are shaped like cones.
Each eye contains approximately 120 million rods compared with only 6 million cones. Rods are more responsive to dim light, which makes them useful for night vision. Cones are more responsive to bright light, such as in the daytime.
Cones contain three different photopigments sensitive to long (red), medium (green), or short (blue) wavelengths of light. The presence of three types of photopigments, each sensitive to a different part of the visual spectrum, gives us our colour vision.
Colour blindness is the result of defects which alter the photopigment's sensitivity to colour. Depending on the type of defect and the cone that is affected problems can arise with red, green, or blue colour vision.
What exactly does a person with colour blindness see?
The obvious answer is that it depends on the nature of their deficiency.
One cone has a weakness...
If they have a 'weakness' of one of the cones but the other two cones function perfectly, then it is referred to as an 'anomaly':
- Red Cone (Protan) = Protanomaly (red-weakness)
- Green (Deutan) = Deuteranomaly (green-weakness)
- Blue (Tritan) = Tritanomaly
One cone doesn't function...
If they are actually 'missing' of one of the cones, but the others function well, then it is 'anopia':
- Red (Protan) = Protanopia
(total red colour blindness)
- Green (Deutan) = Deuteranopia (total green colour blindness)
- Blue (Tritan) = Tritanopia
(total blue colour blindness)
As you can see from the pictures above, red and green deficiencies curiously result in quite comparable colour vision problems. Therefore they are put together under the term red-green colour blindness.
Two cones aren't functioning...
Finally, if they are 'missing' two of the cones (so only one is functioning properly) then it is known as monochromacy or achromatopsia and is extremely rare.
What is the most common form of colour blindness?
The most common type of color blindness is called Deuteranomalia - green cone weakness. Around 4.63% of men and 0.36% of women experience this type of color vision deficiency. Many sufferers don't even realise it's an issue - these people see a more subdued color palette, especially colors with green and red, but otherwise see a large spectrum of colour.
If you want to know more about the most common form of colour blindness, Deuteranomalia, then take a look at my post 'What's It Really Like To Be Colour Blind?'. I experiment on my co-blogger, Oliver, who sufferers from colour blindness to find out exactly what type of colour deficiency he suffers from, how he experiences the world, and find a way for him to see colours they way I do.
For more information on colour blindness or to use their fantastic colour-blindness simulator, head to Colblindor which covers this topic in immense depth.
Do you know someone with colour blindness? What are their experiences of living with it? Let us know your stories in the comments section below.