Can’t See Certain Colors?

If you’ve headed off to work wearing one red sock and one green, maybe you’ve dressed in the dark—or maybe you have a color vision defect.

About 1 in every 76 Americans has a color vision defect, according to the National Center for Health Statistics. The condition is usually inherited from your parents. Men are affected more often than women.

The defect affects cells in the back of the eye called cones, says Dr. Catherine Cukras, a staff clinician at NIH’s National Eye Institute (NEI).

Cones allow us to identify differences between colors. Each of the 3 types of cones is most sensitive to a particular color: red, green or blue. If any of the cone types are damaged or missing, you can’t distinguish between certain colors.

Most people who have color vision defects have trouble seeing differences among colors in the red-green range. Problems with colors in the blue-yellow range are less common. Even more rare is total color blindness, in which the eye can only recognize white, black and shades of gray.

The defects can vary from person to person. “For some, the differences among colors are just not as obvious as for people who have normal color vision,” Cukras says. “For others, different colors can actually look exactly the same.”

Though color vision defects might be inconvenient for people whose careers depend on discerning colors—such as decorators—most people can adapt relatively easily.

“It just means that a lot of men have women pick out their ties,” Cukras says.

You can learn more about eye health from NEI’s “Ask the Doctor” series at www.nei.nih.gov/eyeonnei/askthedoctor.