What is a color blind test?

A color blind test checks if you can accurately see colors.  If you cannot pass the test, you have a form of color blindness. Most color blind tests are screening tests. They can detect color blindness but cannot determine how severe it is. More in-depth color blind testing is needed for that.

Color blind tests can identify children who might have trouble recognizing colors. This could be a factor in certain activities in school and at home.

These tests can also identify people who might struggle at jobs that require excellent color vision.

Screening tests for color blindness

A very popular screening test for detecting the presence of color blindness is the Ishihara Color Vision Test.

Shinobu Ishihara, a Japanese ophthalmologist, developed the test more than 100 years ago. It can quickly detect red-green color blindness (the most common color vision deficiency).

Ishihara plates used to screen patients for color vision problems. Someone with red-green color blindness may not see the red number in this example.

The Ishihara test consists of several circular images (or "plates"). Each image contains many dots of various colors, brightness and sizes.

A person who has normal color vision will be able to detect a visible number "hiding" within the array of dots.

But someone with red-green color blindness won't be able to see the number. Instead, they will see:

• A random pattern of dots, or

• A number different than the one seen by a person with normal color vision.

The complete Ishihara color blind test contains 38 plates. A shorter version of the test (with fewer plates) may be used during an eye exam to screen for color blindness.

The screening takes place under normal room lighting. If you need prescription glasses, you will wear them for this test.

If you fail the Ishihara Color Vision Test, your eye doctor will discuss this with you and whether a more detailed color blind test is recommended.