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Color Vision Defects

  1. Maureen Neitz,
  2. Jay Neitz

Published Online: 27 JAN 2006

DOI: 10.1038/npg.els.0006000



How to Cite

Neitz, M. and Neitz, J. 2006. Color Vision Defects. eLS. .

Author Information

  1. Medical College of Wisconsin, Milwaukee, Wisconsin, USA

Publication History

  1. Published Online: 27 JAN 2006

This is not the most recent version of the article. View current version (15 SEP 2011)

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Figure 1. Tuning of cone photopigment absorption spectra. (a) Absorption curves for S (blue curve), M-class (family of green curves) and L-class (family of red curves) pigments. Wavelength of peak absorption is 415 nm for S pigment, near 530 nm for M-class pigments and near 560 nm for L-class pigments. The rectangular bar below the x axis indicates the color appearance of different wavelengths to a person with normal color vision. (b) Two-dimensional representation of L and M opsins. Balls represent amino acids. Gray balls are invariant amino acid positions among normal L and M opsins. The black ball is the residue to which the chromophore is attached. Red balls are the two amino acid positions that produce the spectral difference between M- and L-class pigments. Yellow balls are positions that produce small spectral shifts and produce subtypes of M and L pigment. Blue balls are variant positions with no influence on the spectrum.

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Figure 2. Comparison of dichromatic and normal color vision. (a) The colors of the visible spectrum as they appear to a person with normal color vision (left) were digitally altered (right) to illustrate the appearance of the same spectrum to a red–green color blind dichromat. (b) Photograph of red and green peppers (left) digitally altered to illustrate the appearance of the same peppers to a red–green color blind dichromat. There are two properties of color: hue and brightness. A person with normal color vision can detect the difference in hue between bell peppers that do not differ significantly in brightness. A dichromat cannot detect the difference in hue, and the peppers appear to be all the same color.

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Figure 3. Recombination between X-chromosome pigment gene arrays required to produce arrays observed in the present-day population underlying normal, protan and deutan color vision. (a) Intergenic recombination between ancestral two-gene arrays that confer normal color vision gives rise to one new array that confers normal color vision and another that confers dichromacy (deuteranopia). (b) Intragenic recombination between two two-gene arrays that confer normal color vision produces two new arrays that both confer color blindness. (c) Intragenic crossover needed to produce protanomalous arrays. The parental three-gene array must be produced by crossover between two ancestral two-gene arrays, and this added step probably accounts for the lower frequency of protanomaly in the population. (d) To delete the M gene from a deutan array requires a crossover between a deutan array with an M gene and another array.