Those with deuteranomaly have defective M-cones and are sensitive to green light. Just as with protanomaly, they see reddish brown and some purple. Green is weaker and less distinctive. Deuteranopia results in seeing far less red and purple and no green. Studies show some people have unilateral deuteranopia: color blindness in one eye. Between approximately one and five percent of men and 0.35 and one percent of women have this type of condition.

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