That refers to the most common form of color blindness, where people have trouble distinguishing RED and GREEN shades. So, for example, in the grocery store, a display of Red Delicious apples might look exactly the same as the Granny Smiths. And in nature, most trees and lawns appear to have a similar yellow shade.

According to the National Eye Institute, about 1-in-20 people have some form of color blindness… but it’s a whopping 16 TIMES more common in men than women! That’s because the condition is linked to a defect in X chromosomes, which controls the color-detecting cells at the back of our eyes. And since women have TWO sets of X chromosomes, the “defective” genes in one X chromosome can be offset by the healthier genes in the other X.

Most people with deuteranopia live perfectly normal lives. But the condition can be DANGEROUS if you have trouble distinguishing colors on traffic lights and road signs! That’s why it’s important to have your eyes checked regularly by an eye doctor, who can test for color blindness. And if you DO have a problem, doctors may be able to prescribe special glasses, which emphasize the shades your eyes normally can’t detect.