What You Need to Know About Color Blindness Tests

Medically Reviewed by Whitney Seltman, OD on March 13, 2024
3 min read

Do you have a hunch that you don’t see colors as clearly you should? Ever been told that something has different shades, but they all look the same to you? If so, you could be color blind.

Some people are color blind and don’t know it. For example, they know tree leaves are green, so they think the color they see is “green.”

This vision issue usually doesn’t make you see things in shades of gray. That’s rare. Most people who are color blind have trouble telling some colors apart. They may not be able to tell the difference between red and green or blue and yellow.

Eye professionals have lots of ways to check for the condition. The most common tests use colored tablets or diagrams.

If you notice a serious change in how you see color, call an ophthalmologist or optometrist. They are  trained in eye care and vision. Your symptoms could be a warning sign of something more serious, so it's a good idea to get them checked out. You should also tell your regular doctor if you think you’re having trouble seeing colors.

In some schools, nurses test children for color problems.

Color blindness runs in families. If you have relatives with the condition, it’s important to get tested.

Ishihara color test. This checks for red-green color blindness. The doctor will ask you to look at a series of circles (also called plates) with dots of different colors and sizes. Some of the dots form shapes or one- or two-digit numbers. If you have trouble seeing red and green, those shapes will be hard to see, or you may not see them at all.

Cambridge color test. This is a lot like the Ishihara test, except that you look at a computer screen. You’ll try to find a “C” shape that’s a different color than the background. It pops up randomly. When you see it, you press one of four keys.

Anomaloscope. You look through an eyepiece and see a circle. The top half of the circle is a yellow light. The bottom half is made up of red and green lights. You turn knobs until both halves are the same color and brightness. Doctors use this test to check for trouble seeing red and green.

Farnsworth-Munsell 100 hue test. This uses blocks or pegs that are different shades of the same color. Your task is to line them up a certain way. This test checks to see if you can pick up slight color changes. Companies that need workers to see colors correctly sometimes use it.

Farnsworth lantern test. The U.S. military uses this to see if recruits have a mild or severe form of color blindness. You can serve in the armed forces if your condition is mild.

Being color blind can make some things tricky, but it’s not serious. You can still drive, work, and live a normal life. You may need to find other ways to do some things, though. Some people with red-and-green color blindness wear special contact lenses. Others download apps to help them with colors.