Color blindness

Color blindness (color vision deficiency) is the decreased ability to see color or differences in color.[3] It can impair tasks such as selecting ripe fruit, choosing clothing, and reading traffic lights.[3] Color blindness may make some educational activities more difficult.[3] However, problems are generally minor, and most color-blind people adapt.[3] People with total color blindness (achromatopsia) may also be uncomfortable in bright environments[3] and have decreased visual acuity.

Color blindness
Other namesColour blindness, color deficiency, impaired color vision[1]
An Ishihara color test plate. With properly configured computer displays, people with normal vision should see the number "74". Viewers with red-green color blindness will read it as "21",[2] and those with total color blindness may not see any numbers.
SymptomsDecreased ability to see colors[3]
DurationLong term[3]
CausesGenetic (inherited usually X-linked)[3]
Diagnostic methodIshihara color test[3]
TreatmentAdjustments to teaching methods, mobile apps[1][3]
FrequencyRed–green: 8% males, 0.5% females (Northern European descent)[3]

The most common cause of color blindness is an inherited problem in the development of one or more of the three sets of the eyes' cone cells, which sense color.[3] Among humans, males are more likely to be color blind than females, because the genes responsible for the most common forms of color blindness are on the X chromosome.[3] Females have two X chromosomes, so a defect in one is typically compensated for by the other. Non-color-blind females can carry genes for color blindness and pass them on to their children.[3] Males only have one X chromosome and therefore always express the genetic disorder if they have the recessive gene.[3] Color blindness can also result from physical or chemical damage to the eye, the optic nerve, or parts of the brain.[3] Diagnosis is typically with the Ishihara color test; other methods include genetic testing.[3][4]

There is no cure for color blindness.[3] Diagnosis may allow a person's teacher to change the teaching method to accommodate the condition.[1] Special lenses such as X-chrome lenses may help people with red–green color blindness in bright light.[3] Mobile apps can help people identify colors.[3]

Red–green color blindness is the most common form, followed by blue–yellow color blindness and total color blindness.[3] Red–green color blindness affects up to 8% of males and 0.5% of females of Northern European descent.[3][5] The ability to see color also decreases in old age.[3] In certain countries, color blindness may make people ineligible for certain jobs,[1] such as those of aircraft pilots, train drivers, crane operators, and people in the armed forces.[1][6] The effect of color blindness on artistic ability is controversial.[1][7] The ability to draw appears to be unchanged, and a number of famous artists are believed to have been color blind.[1][8]