To understand what causes color blindness, you need to understand how your eyes see objectives. Our eyes see objectives by light stimulating the retina, a neuro-membrane at the back of the eyes. The retina is made up of Rods and Cones. While the rods give you night vision; the cones let you see color during daylight.

The cones, about the size of a postage stamp, are located in the center of the retina. There are "red," "blue," and "green" cones. If you don't have all the three types, or your cones don't work properly, your brain can't tell the right colors you're seeing.

Color blindness is often an inherited trait, but can also occur because of some nerve, eye, or brain damage, or exposure to certain chemicals.You can ask your eye doctors for a test for color blindness.

According to some studies, more than 5% of the men in the world are born color blind, while only 0.5% for women. So, one in twenty men, is at least a little color blind.