Nearly all people who are “colour blind” can see colours but have difficulty distinguishing between certain colours. Not all people who are colour blind have trouble with the same colours – most cannot distinguish between reds and greens in dim light; some cannot separate blues from yellows; and a very small group have a condition called monochromatism which only allows them to see black and white.
Colour blindness of various kinds affects roughly 7% of men – and less than 1% of women.
What Causes Colour Blindness?
Colour blindness is a genetic condition caused by a difference in how one or more of the light-sensitive cells found in the retina of the eye respond to certain colours. These cells, called cones, sense wavelengths of light, and enable the retina to distinguish between colours. This difference in sensitivity in one or more cones can make a person colour blind.
Symptoms of Colour Blindness
The symptoms of colour blindness are often observed by parents when children are young. In other cases, symptoms are so slight, they may not even be noticed. Common symptoms of colour blindness include:
Difficulty distinguishing between colours
Inability to see shades or tones of the same colour
Rapid eye movement (in rare cases)
Treatment for Colour Blindness
There is no known treatment for colour blindness. Fortunately, the vision of most colour-blind people is normal in all other respects and certain adaptation methods are all that is required.