Colour blindness is a condition in which a person has difficulty distinguishing between specific colours. Causes and symptoms vary according to the form of colour blindness, but most sufferers lead normal lives. What are the different forms of colour blindness? What tests can be used to diagnose it? Our eye care professionals answer your questions.
Colour blindness or colour perception
Colour blindness, also known as “dyschromatopsia” or “colour perception deficiency,” is a visual disorder that alters colour perception. It can be hereditary (genetic colour blindness) or acquired over a lifetime.
Malperceived colours vary from one individual to another. Most colour-blind people have difficulty distinguishing between red and green, although there are other types of colour blindness. The forms are equally diverse, ranging from mild to severe, but they often do not interfere with daily life.
If you have any concerns about your colour vision, it's advisable to consult an optometrist for an eye exam.
The different types of colour blindness
There are three main types of colour blindness:
- Protanopic colour blindness: difficulty perceiving shades of red, often confused with green.
- Deuteranopic colour blindness: difficulty distinguishing green from red.
- Tritanopic daltonism is less frequent. It affects the perception of blue, which can be confused with green or violet.
Rarer forms, such as achromatopsia, result in a total absence of colour perception.
Daltonism in men and women
Approximately 8% of men and 1% of women are colour-blind. Based on Western populations, these figures may vary from region to region. Screening tests are often carried out during childhood.
Causes of colour blindness
Colour blindness is generally hereditary, linked to genetic variations affecting the cones of the eye, which are responsible for colour perception. Men are more often affected than women. Acquired colour blindness can result from eye injury, disease or exposure to toxic substances.
Certain conditions such as glaucoma, macular degeneration, uncontrolled diabetes or multiple sclerosis may be associated with colour blindness. Aging eyes can also impair colour perception.
Screening for colour blindness is generally carried out using coloured dot cards. The most accurate test, the anomaloscope, evaluates the ability to adjust red and green light to obtain yellow light, thus determining the degree of colour blindness.
Treatments for colour blindness
Colour blindness of genetic origin is incurable, but in acquired colour blindness, treatment of the underlying cause can sometimes alleviate symptoms. In more severe forms, special glasses or lenses can help adjust colours.
Most colour-blind people suffer only a slight variation in colour perception and lead normal lives.
