Health and Beauty Tips

hina

As Seen By The Color Blind

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Color blindness affects a significant amount of the population, and it is even more prevalent in more isolated populations with a smaller gene pools. Those affected either cannot distinguish red from green, or see red and green differently. It is mostly a genetic condition, though it can be caused by eye, nerve, or brain damage, or due to exposure to certain chemicals.

For those of us who see colors just fine, it is hard to imagine what those with color blindness are seeing. Luckily humans are smart and have methods to show how the world looks to the color blind. Here are a few examples from some popular websites showing how they look like to people suffering from color blindness.

Iconic Art: As Seen by the Color Blind

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http://nicefun.net/userpix/5_armand_colorblind_1.jpg

http://nicefun.net/userpix/5_warhol_colorblind_1.jpg

http://nicefun.net/userpix/5_thescream_colorblind_1.jpg

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hina

Color Blindness Background

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The normal human retina contains two kinds of light cells: the rod cells (active in low light) and the cone cells (active in normal daylight). Normally, there are three kinds of cones, each containing a different pigment. The cones are activated when the pigments absorb light. The absorption spectra of the cones differ; one is maximally sensitive to short wavelengths, one to medium wavelengths, and the third to long wavelengths (their peak sensitivities are in the blue, yellowish-green, and yellow regions of the spectrum, respectively). The absorption spectra of all three systems cover much of the visible spectrum, so it is not entirely accurate to refer to them as “blue”, “green” and “red” receptors, especially because the “red” receptor actually has its peak sensitivity in the yellow. The sensitivity of normal color vision actually depends on the overlap between the absorption spectra of the three systems: different colors are recognized when the different types of cone are stimulated to different extents. Red light, for example, stimulates the long wavelength cones much more than either of the others, and reducing wavelength causes the other two cone systems to be increasingly stimulated, causing a gradual change in hue. Many of the genes involved in color vision are on the X chromosome, making color blindness more common in males than in females.

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hina

Types of Color Blindness

There are three types of inherited or congenital color vision deficiencies: monochromacy, dichromacy, and anomalous trichromacy.

Monochromacy

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Monochromacy, also known as “total color blindness”, is the lack of ability to distinguish colors; caused by cone defect or absence. Monochromacy occurs when two or all three of the cone pigments are missing and color and lightness vision is reduced to one dimension.