Colour blindness is when a person has difficulty seeing specific colours. The causes and symptoms of colour blindness vary, as there are many different forms. That said, the majority of colour-blind people lead normal lives. What is colour blindness? What are the different types of colour blindness? What tests are available? Our eye professionals share their answers with you.
Colour blindness and colour perception
Colour blindness is a vision dysfunction resulting in impaired colour perception. You may also hear the terms "dyschromatopsia" or "colour perception deficiency" used to describe colour blindness.
This eye condition can be hereditary. This is known as genetic colour blindness. But colour blindness can also occur at a certain point in your life. This is known as acquired colour blindness.
It's also interesting that colour-blind people don't always perceive the same colours differently. Most have difficulty distinguishing between green and red. However, there are other types of colour blindness.
What's more, the form of colour blindness varies too. Most sufferers have moderate symptoms that do not interfere with their daily lives. However, some people have more severe forms of colour blindness.
If you have concerns about your colour vision, we recommend you make an appointment for an accurate diagnosis.
What are the different types of colour blindness?
There are three main types of colour blindness.
Protanopic colour blindness
People with this type of colour blindness have difficulty perceiving colours in the red part of the spectrum. All shades of red appear dull, and they confuse red with green.
Deuteranopic colour blindness
This type of colour blindness affects the perception of colours in the green part of the spectrum. Affected individuals have difficulty distinguishing green from red and may confuse the two.
Tritanopic colour blindness
Less frequent than the two previous types, this type of colour blindness affects the perception of colours in the blue part of the spectrum. Affected individuals may confuse blue with green or violet.
There are also other, rarer forms of colour blindness which have a more significant impact on people's lives. This is the case, for example, with achromatopsia, which corresponds to a total absence of colour vision.
Colour blindness in men and women
It is estimated that around 8% of men and 1% of women are affected by colour blindness. Most cases are detected in childhood through eye tests carried out by optometrists.
However, note that this rate corresponds to estimates based on a Western population. This rate may vary according to populations and geographical regions.
What causes colour blindness?
Colour blindness is a hereditary condition linked to genetic variations in the chromosomes. This variation affects the eye's cones responsible for colour perception. As we have just seen, this genetic variation affects men more than women.
Colour blindness can also be acquired due to an eye injury, eye disease or exposure to certain toxic substances. In this case, colour blindness can affect women and men equally.
Certain diseases can be associated with colour blindness, including glaucoma, macular degeneration, cataracts, uncontrolled diabetes and multiple sclerosis. Decreased colour perception may also be a natural effect of aging eyes.
What test can tell you if you're colour-blind?
Colour-blindness tests are carried out in daylight, using cards representing an image of coloured dots. You've probably already seen these cards in a health professional's clinic. Generally, the person being tested is asked whether they can read a number or word in the image of dots.
A more complex test is carried out using an instrument called an anomaloscope. During the test, the person is exposed to red and green light. They are then asked to adjust the light until a yellow light is obtained. This way, it is possible to assess the degree of colour blindness by observing the person's propensity to perceive more red or green.
Is there a treatment for colour blindness?
When colour blindness is an inherited condition linked to genetic variations, it is incurable. But in the case of acquired colour blindness, it can sometimes be eliminated or reduced by treating the disease or injury that caused the problem in the first place.
Most colour-blind people are not bothered by a slight variation in colour perception. They lead completely normal lives.
More advanced colour blindness can affect certain activities, such as driving. Indeed, the person will have difficulty distinguishing colours on different road signs. However, special glasses and contact lenses can be prescribed to adjust colours.
