What Is Colorblindness?

Colorblindness means your eye doesn't see color the way it should.

Your eyes see differences in the light that comes in. It’s a bit like the way we hear sounds as being low or high. This is called pitch, and it corresponds to the frequency of the sound, or how many times it vibrates in a given time period.

The keys on the left side of a piano keyboard make low-frequency sounds. The frequency rises as you go to the right. There’s a similar order to the colors we see.

The colors of every rainbow always appear in the same order: red, orange, yellow, green, blue, indigo, and violet. The different colors in each part of the rainbow correspond to a different wavelength of light. Reddish colors have a long wavelength. Bluish colors are shorter. Just as there are many notes on the piano, there are many wavelengths of light that match the different colors.

How Does Your Eye See Colors?

Think of your eye as a camera. The front part has a lens. Its job is to focus images on the inside of the back of your eye. This area is called the retina. It’s covered with special nerve cells that contain pigments that react to light:

Cones control your color vision. There are several kinds of pigments present in three types of cone cells. Some react to short-wavelength light, others react to medium wavelengths, and others react to higher wavelengths

Rods only have one kind of pigment. It reacts the same way to any light wavelength. Rods don’t have anything to do with color vision. But they are very sensitive to light and allow us to see at night.

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What Is Colorblindness?

When the cones have all the various pigments, your eye sees all possible colors. If there’s a problem with the pigments, you won’t see colors the way you should. This is called color deficiency or colorblindness.

If just one pigment is missing, you might only have trouble with seeing certain colors.

Incomplete red-green color deficiency is the most common. People with it find it hard to tell red from green.

Blue-yellow colorblindness is the second most common. There are two forms. Both cause blues to look green. Yellow might look red or pink to some people but appear violet or gray to others.

If you don’t have any pigments in your cones, you won’t see color at all. This is known as achromatopsia.

What Causes Colorblindness?

It’s a genetic condition. You get it from your parents. It happens because your eyes don’t make all the pigments you need for color vision. It affects men more often than women.

Does Colorblindness Cause Other Health Problems?

The kind that’s present at birth doesn't. Most people who are colorblind lead normal and complete lives. The condition might keep you from a job -- like a pilot -- that requires a certain level of color vision.

If you think you have a problem with color vision, talk to your eye doctor right away. She can tell you if you’re seeing colors properly and what to do if you aren't.

WebMD Medical Reference Reviewed by Alan Kozarsky, MD on December 08, 2016

Sources

SOURCES:

American Association for Pediatric Ophthalmology and Strabismus: "Color Blindness."

American Academy of Ophthalmology, geteyesmart.org: "What is Color Blindness?"

NDT Resource Center: “Frequency and Pitch.”

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