In the power of conceiving colors, too, there are striking differences among individuals: and, indeed, I am inclined to suspect, that, in the greater number of instances, the supposed defects of sight in this respect ought to be ascribed rather to a defect in the power of conception. The phenomenon only came to be scientifically studied in 1794, when English chemist John Dalton gave the first account of colour blindness in a paper to the Manchester Literary and Philosophical Society, which was published in 1798 as Extraordinary Facts relating to the Vision of Colours: With Observations. Genetic analysis of Daltons preserved eyeball confirmed him as having deuteranopia in 1995, some 150 years after his death.Influenced by Dalton, German writer J. W. von Goethe studied color vision abnormalities in 1798 by asking two young subjects to match pairs of colors.In 1875, the Lagerlunda train crash in Sweden brought color blindness to the forefront. Following the crash, Professor Alarik Frithiof Holmgren, a physiologist, investigated and concluded that the color blindness of the engineer (who had died) had caused the crash. Professor Holmgren then created the first test for color vision using multicolored skeins of wool to detect color blindness and thereby exclude the colorblind from jobs in the transportation industry requiring color vision to interpret safety signals.
Color blindness (color vision deficiency) is the decreased ability to see color or differences in color. It can impair tasks such as selecting ripe fruit, choosing clothing, and reading traffic lights. Color blindness may make some academic activities more difficult. However, issues are generally minor, and the colorblind automatically develop adaptations and coping mechanisms. People with total color blindness (achromatopsia) may also be uncomfortable in bright environments and have decreased visual acuity. The most common cause of color blindness is an inherited problem or variation in the functionality of one or more of the three classes of cone cells in the retina, which mediate color vision. 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. Non-color-blind females can carry genes for color blindness and pass them on to their children. Color blindness can also result from physical or chemical damage to the eye, the optic nerve, or parts of the brain. Screening for color blindness is typically done with the Ishihara color test.There is no cure for color blindness. Diagnosis may allow an individual, or their parents/teachers to actively accommodate the condition. Special lenses such as EnChroma glasses or X-chrom contact lenses may help people with red–green color blindness at some color tasks, but they do not grant the wearer "normal color vision". Mobile apps can help people identify colors.Red–green color blindness is the most common form, followed by blue–yellow color blindness and total color blindness.