Color deficiency is a lack of the ability to discriminate between colors. Designs that rely totally on color to convey essential information will be inaccessible to a small percentage of women and a larger percentage of men.
inability to distinguish some colors and shades; occurs when the color-sensitive cone cells in the retina do not properly pick up or send normal color signals to the brain
a reduced ability to detect and distinguish some colors; 8-10% of Caucasian males, 4% of non-Caucasian males, and .5% of all females are born with some variation of the possible deficiencies in color vision (Thorell & Smith, 1990).