Definition There are two types of colour blindness:
achromatopsia (ack-row-ma-top- see-ah), in which you cannot see colour.
dyschromatopsia (dis-crow-ma-top-see-ah), in which you can see some colour. Since some colours are seen, the term "colour defective" rather than "colour blindness" may be better suited for this condition.
What is going on in the body? The eye cannot tell the difference between colours. Some people with achromatopsia can only see shades of grey. A person with this condition usually has poor distance vision, light sensitivity, and rapid eye movement.
Dyschromatopsia is the more common form of colour blindness. Individuals with this condition usually have excellent vision. The person usually cannot tell the difference between shades of red and green. In rare cases, the person cannot tell the difference between shades of blue and yellow. This makes it difficult to match colours.
What are the signs and symptoms of the condition? The signs and symptoms of colour blindness may include:
only seeing shades of grey
difficulty telling the difference between reds and greens
difficulty telling the difference between blues and yellows
poor vision
What are the causes and risks of the condition? Colour blindness is caused by an inherited trait. Dyschromatopsia, or the inability to see some colours, occurs in about 8% of men and less than 1% of women.
What can be done to prevent the condition? Colour blind people can be identified through genetic counseling if the condition is uncovered through the person's family history.
How is the condition diagnosed? Colour blindness is usually self-diagnosed. Achromatopsia may not be uncovered until a child is 3 to 5 years old. To confirm the self-diagnosis, a doctor usually performs a colour test, such as the HRR pseudoisochromatic plates or the Ishihara plates. The diagnosis of achromatopsia is sometimes determined by performing an electric eye test. This test is called an electroretinograph.
What are the long-term effects of the condition? There is no known treatment for colour blindness. Determining colour blindness as early as possible can help individuals cope with employment, hobbies, and games that require more exact colour vision.
What are the risks to others? There are few risks to being colour blind. Individuals with dyschromatopsia can see the difference between bright red and green as in traffic lights. However, this could be risky if the person drives or operates heavy machinery. Proper precautions should be taken.
What are the treatments for the condition? There are no known medical, surgical, or nutritional treatments available for colour blindness.
How is the condition monitored? Periodic eye examinations are important for children with this condition. Wearing dark lens glasses can sometimes help individuals with achromatopsia.
Author: Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
