Many of you have probably heard the term Colour Blind before. You may even know someone who is colour blind to a greater or lesser degree. But do you know what it means? Does it mean that you see the world in black and white? Well, not exactly. In fact, some people may be colour blind and not even aware of it.
Colour Vision Deficiency
Colour Vision Deficiency (CVD) (not to be confused with Cardiovascular Disease with the same acronym) causes those affected to perceive colours differently from those who do not have it. Most people who have CVD are usually not even aware that they see colours differently, unless it is pointed out to them. In many cases, mild forms of colour blindness may fly under the radar and not affect a person’s life much. Mismatched clothing may be written off as eccentricity, trend setting, or, since colour blindness affects men more than women, just a guy’s lack of fashion sense. However more serious cases of colour blindness could be dangerous, especially since one of the more common cases is red/green colour blindness, the colours of traffic lights.
How do you get Colour Blindness?
In the vast majority of cases, colour blindness is inherited, known as a Congenital Condition. Inherited colour blindness affects approximately eight per of men and .5 percent of women. This is because the gene for colour blindness is in the X chromosome and men have two X’s whereas women have only one. Women are usually the carrier of the colour blindness gene, even if they are not colour blind themselves. Non-hereditary colour blindness can be caused by trauma, drug abuse, or through side effects of Glaucoma, Diabetes, Macular Degeneration, Alzheimer’s disease, Parkinson’s disease or Sickle Cell Anemia.
Varieties of Colour Blindness
There are two main types of colour blindness in which there are several sub-categories. The most common type is red/green colour blindness, which affects the red (protan) and green (deutran) Photopigments of the eye. This category is broken down into four sub-categories. In the first, Protanomaly, red, orange and yellow all appear greener, and colours aren’t as bright as they would be without the condition. It is usually mild and often doesn’t affect lifestyle. The next, Protanopia, causes red to appear black, and many shades of yellow orange and green may all appear to be yellow. Deuteranomaly causes yellow and green to appear redder and makes it difficult to tell violet from blue. This condition is usually mild and quite common. The last, Deuteranopia, causes red to appear brownish-yellow and green to appear beige.
A more rare type of colour blindness is blue/yellow, which usually affects the blue (tritan) photopigments. One form is called Tritanomaly, which causes blue to appear greener and makes it hard to differentiate red and yellow from pink. The second type is Tritanopia, which causes blue to appear green and yellow to appear either violet or grey. Unlike red/green colour blindness, these rare conditions affect males and females equally. Another rare and severe form of colour blindness is Achromatopsia, in which none of the photopigments are functioning. People with Achromatopsia experience the world in shades of grey, black and white.
What can You Do About Colour Blindness?
If a person has acquired colour blindness through illness or injury, the solution may be as simple as dealing with the cause. Unfortunately, at this time, there is very little that can be done about hereditary colour blindness. In some cases, coloured lenses or contact lenses can help enhance the difference between colours, but it doesn’t always help and in some cases may even confuse the colour blind person even more. In most cases, the best a colour blind person can do is learn to adapt and adjust to the visual deficiency. If you think that you may be colour blind or have a colour vision deficiency, see your optometrist to find out, and to get advice about how to deal with any concerns you may have.