Color blindness affects approximately 300 million people worldwide and occurs more frequently in men. One in 12 men and 1 in 200 women are color blind. Those with a mild form of color blindness may not even be aware of their condition!

In the simplest sense, people with color blindness are not able to perceive the differences between various colors.

To understand color blindness a bit better, let’s review how we see color.

How does the human eye see?

You may remember from biology that the retina of the eye contains two types of light-sensitive cells: rods and cones. Rods work in low-light conditions (think night vision), and cones work in daylight, helping us see color.

We have three different kinds of cone cells, and each type of cells responds to either blue, green or red light (light wavelengths).

So, when we look at something, light enters our eyes, stimulates the cone cells, and then our brain interprets the signals from the cones cells to determine the color of the object. Together, blue, green and red cones allow us to see the whole spectrum of colors.

Each of the three types of cone cells has a different makeup of photopigment cells, which are molecules that undergo a chemical change when they absorb different types of light.

Are there different kinds of color blindness?

There are a few types of color blindness. Red-green color blindness is the most common, followed by blue-yellow color blindness. A complete absence of color vision —total color blindness – also occurs, but it’s quite rare.

Someone with red-green color blindness typically confuses blue and purple because they cannot detect the red element of the color purple.

What causes color blindness?

Most color blindness is genetic. A mother can pass on color blindness to her son since it is encoded on the x-chromosome — hence why more men are color blind. Inherited color blindness is a result of abnormal photopigments, the color-detecting molecules inside the cone-shaped cells of the retina.

Other times, color blindness can be caused by physical or chemical damage to the eye, optic nerve, or parts of the brain that process color information. In addition, with age, the hardening of the eye’s lens (which leads to cataracts) can also affect color vision. Cataracts, however, can be corrected with surgery.

Most color blind people see things just as clearly as other people, with the exception of not being able to fully perceive red, green or blue light.

Curious how well you can distinguish between different colors? Try this neat color test to see how you do:

And remember, if your results are concerning or alarming in any way, please schedule an appointment with your optometrist to discuss your questions or concerns.



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