What is Red and Green Color Blindness?

Red and green color blindness is a condition in which a person cannot easily distinguish between various shades of green and red. A person affected by this condition will typically perceive a number of different colors — those that contain red and green — as muddied or gray in color. This can make it difficult for a person with this type of color blindness to differentiate between different markings and colorations of food. Red and green color blindness is a genetic condition that is the most common form of color blindness and is primarily found in men, though women can very rarely have this form of color blindness.

Also called deutan color blindness or Daltonism after the person who first documented this condition, red and green color blindness seems to affect about 8-12% of males. The condition manifests as an inability to properly distinguish between red and green and improperly view colors that contain these two primary colors. Someone with red and green color blindness is not “blind” in the sense that he or she cannot perceive color; the colors are simply not perceived accurately. The term “color vision deficiency” is often used rather than “color blindness” as a more accurate descriptor of the condition.

Red and green color blindness is most common among males because the genes that control the proper development of red and green color receptors in the eyes are located in the X chromosome. Women have two X chromosomes, one from their father and one from their mother. If either X chromosome can properly develop the red and green color receptors for the person, then she will not have red and green color blindness but can still be a carrier of the condition. Men only receive a single X chromosome from their mother, so if they receive the affected chromosome from a mother who is a carrier then they will be color blind.

There are a number of different negative consequences that red and green color blindness can cause. Choosing ripe fruits and vegetables based on color can often be difficult and different types of apples can appear the same greenish color, rather than varying shades of red, green, and yellow. It can similarly be difficult to tell when meat is cooked through and no longer raw, and distinguishing between ketchup and chocolate sauce can be impossible without a label. Traffic lights may also be hard to distinguish for someone with red and green color blindness, so someone with the condition must learn to recognize each light based on position rather than color.