Color blindness - Wikipedia, the free encyclopedia


** Color blindness **

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This article is about color blindness in humans. For color blindness in
other species, see Color vision.
"Colorblind" and "Colourblind" redirect here. For other uses, see
Colorblind (disambiguation).

Color blindness or color deficiency
/Classification and external resources/

An 1895 illustration of normal vision and various kinds of color blindness
ICD-10 H53.5
ICD-9 368.5
DiseasesDB 2999
MedlinePlus 001002
MeSH D003117

*Color blindness*, or *color vision deficiency*, is the inability or
decreased ability to see color, or perceive color differences, under normal
lighting conditions. Color blindness affects a significant percentage of
the population.^[1] There is no actual blindness but there is a deficiency
of color vision. The most usual cause is a fault in the development of one
or more sets of retinal cones that perceive color in light and transmit
that information to the optic nerve. This type of color blindness is
usually a sex-linked condition. The genes that produce photopigments are
carried on the X chromosome; if some of these genes are missing or damaged,
color blindness will be expressed in males with a higher probability than
in females because males only have one X chromosome (in females, a
functional gene on only one of the two X chromosomes is sufficient to yield
the needed photopigments).^[2]

Color blindness can also be produced by physical or chemical damage to the
eye, the optic nerve, or parts of the brain. For example, people with
achromatopsia suffer from a completely different disorder, but are
nevertheless unable to see colors.

The English chemist John Dalton published the first scientific paper on
this subject in 1798, "Extraordinary facts relating to the vision of
colours",^[3] after the realization


can girls be color blind

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