What is colour vision deficiency?

The following was written by Bill Evans and published in the Coolum and North Shore News, Ask the Professionals page on Friday, 28th January 2011.

Q: What is colour vision deficiency?

Colour vision deficiency, also known as colour blindness, is the inability of a person to distinguish between colours that other people can see as different. People with normal colour vision have photoreceptors in their retina each containing one of three pigments; red, green or blue. With the most common type of genetic colour vision deficiency, the cells containing either the red pigment or the green pigment are not present in the retina. Some people may be only mildly colour deficient; they can tell a bright red object from a bright green one, such as traffic lights, but they may struggle with pastel colours and confuse pale greens and pale reds with grey. Other people with colour vision deficiency may not even distinguish between red and green.

There has been some exciting research conducted into genetic colour vision deficiency. Researchers have been applying gene therapy to monkeys with remarkable results. The monkeys, having been colour blind from birth, have gone from having only two pigmented cell types in the retina to having all three, and seeing the full spectrum of colour for the first time.