Colour Blind Test

The most common cause of color blindness is due to a fault in the development of one or more of the three sets of color sensing cones in the eye. Males are more likely to be color blind than females as the genes responsible for the most common forms of color blindness are on the X chromosome. As females have two X chromosomes, a defect in one is typically compensated for by the other, while males only have one X chromosome. Color blindness can also result from physical or chemical damage to the eye, optic nerve, or parts of the brain. Diagnosis is typically with the Ishihara color test; however a number of other testing methods also exist.[2]

There is no cure for color blindness.[2] Diagnosis may allow a person's teacher to change their method of teaching to accommodate the decreased ability to recognize color.[1] Special lenses may help people with red-green color blindness when under bright conditions. There are also mobile apps that can help people identify colors.[2]

Red-green color blindness is the most common form, followed by blue-yellow color blindness and total color blindness. Red-green color blindness affects up to 8% of males and 0.5% of females of Northern European descent. The ability to see color also decreases in old age.[2] Being color blind may make people ineligible for certain jobs in certain countries. This may include pilot, train driver, and armed forces. The effect of color blindness on artistic ability, however, is controversial. The ability to draw appears to be unchanged and a number of famous artists are believed to have been color blind

Color vision deficiencies can be classified as acquired or inherited.

Deuteranopia is a type of color vision deficiency where the green photoreceptors are absent. It affects hue discrimination in the same way as protanopia, but without the dimming effect. Like protanopia, it is hereditary, sex-linked, and found in about 1% of the male population.[6]

Protanomaly is a mild color vision defect in which an altered spectral sensitivity of red retinal receptors (closer to green receptor response) results in poor red - green hue discrimination. It is hereditary, sex-linked, and present in 1% of males. The difference with protanopia is that in this case the L-cone is present but malfunctioning, whereas in the earlier the L-cone is completely missing.[7]