Color Vision Deficiency

Color Vision Deficiency (a.k.a. "color blindness") is a kind of vision impairment that causes a person to have difficulty perceiving certain colors.  It is a relatively common impairment, affecting up to 8% of men and about 0.5% of women.  The most common type of color vision deficiency results in difficulties in distinguishing between reds and greens, but other forms of color vision deficiencies also exist. Although common terms like "red-green color blindness" suggest complete inability to distinguish between some colors, most affected people experience partial color vision deficiencies -- they perceive the differences less well than people with typical vision.

The high prevalence of color vision deficiencies in the world population has implications for accessible design.  In particular, good design should avoid using hue as the sole means of communicating important information.  Instead, redundant cues should be used.

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