Colour Blindness, daltonismo, Farbenfehlsichtigkeit , 色覚異常, дальтонизм

Color blindness is an inaccurate term to describe a lack of perceptual sensitivity to certain colors, a more precise term is Color Vision Deficiency (CVD). Color blindness is, however, the most commonly used term though it is misleading if taken literally, because colorblind people CAN see colors, but cannot make out the difference between some couples of complementary colors. Color vision deficiency is not related to visual acuity at all and is most commonly due to an inherited condition. Red/Green color vision deficiency is by far the most common form, about 99%, and causes problems in distinguishing reds and greens. Another color vision deficiency Blue/Yellow also exists, but is rare and there is no commonly available test for it.

Shinobu Ishihara

The most commonly used test to detect color vision deficiencies was developed by the Japanese ophthalmologist Shinobu Ishihara (1879-1963). This test is called The Ishihara Plate Test. More about him, pay a visit to this link... http://en.wikipedia.org/wiki/Shinobu_Ishihara

you should see the number 74!

42

16

8

57

There is no treatment for color vision deficiency, nor is it usually the cause of any significant disability. Actually, most color deficient persons compensate well for their defect. At one time the U.S. Army found that colorblind persons can spot 'camouflage' colors where those with normal color vision are fooled by them. In fact, a reduction in color signals makes the differences in texture and brightness more apparent.

Reverse color blindness test
Color vision deficient people have a tendency to better night vision and, in some situations, they can perceive variations in luminosity that color-sighted people could not. Only color blind people can actually read what is written in the picture above... That means, if you fail the test, you probably have the full range of color sensitivity that is attributed to color-sighted people.