10/14/2025
"Colourblindness"... What Is It?
Colourblindness isn’t really what it sounds like. Most people with the condition can see some colours correctly but can’t pick out others. “Colour deficiency” might be a better name. Whatever you call it, it’s more common in men than women. About 1 in 12 men have a colour deficiency, compared with about 1 in 200 women.
With the most common kind of colour deficiency, it's hard to tell the difference between some shades of red and green. Other people have a type that makes you confuse certain shades of blue and yellow. Either one can be mild, moderate, or severe.
Most people who have a colour deficiency are born with it. That’s because it usually begins with the genes you get from your parents. Those genes don't provide your eyes the proper information on how to make blue, red, and green pigments for your cones. Without the pigments, the cones can’t detect the proper colours and the brain misinterprets the colour value.
Colour deficiency can also affect some people who aren’t born with it. Certain eye diseases can lead to it, and it also can happen along with leukemia, Parkinson’s disease, Alzheimer’s disease, sickle cell anemia, or alcohol use disorder.
Some drugs, including some that treat heart disease, high blood pressure, erectile dysfunction, nervous ailments, or emotional disorders can have an effect on colour perception. Colour perception issues also can come from working around chemicals like fertilizers or solvents. But while things like taking certain drugs or working with certain chemicals can cause secondary colour deficiency, it is uncommon.
Living With It...
Apps for your cellphone or tablet computer can tell you what colour something is. You take a photo, and when you tap on a place in the image, the app tells you the colour. Some apps can even tell shades of colours. If you have red-green colour deficiency, special lenses may let you see colours more clearly, although their effectiveness is widely controversial. For instance, special lenses to correct for colour deficiency are not permitted for pilots.