Online color blindness tests may give people an idea of whether they may be color blind and if so, which type of color blindness they might have.

This information comes from the National Eye Institute (NEI).

Ishihara plates consist of many colored dots, which create a picture. Using the various combinations of colors and shapes within the plates, a doctor can tell if a person sees colors differently than others.

In this article, we explain how the Ishihara test works and then look at a real example of an online color blindness test.

Many online tests that can identify color blindness are variations of the Ishihara test. To take the test, people look at a series of colored plates that contain different colored spots. The spots make up an image.

The spots making up the image background are in various shades of one color, while spots making up a specific shape are in various shades of a second color. For example, the background spots may be green, while the shape consists of red spots.

People without color blindness are able to clearly see the image within the spots. If they cannot, they may have a type of color blindness.

Digital Ishihara tests can work just as well as traditional paper tests. However, it is important to note that only a doctor can make an official diagnosis.

Below is an example of an Ishihara color blindness test. It may give people an idea of whether they may have color blindness.

The table below lists the correct answers to each plate. Click to expand the results.

Plate numberAnswer
26purple and red spots
27purple and red spots
30blue-green line
31blue-green line
32orange line
33orange line
34blue-green and yellow-green line
35blue-green and yellow-green line
36pink and orange line
37pink and orange line
38everyone should see a line

If a person cannot see the image in some of the Ishihara plates, they may have a type of color blindness. Doctors determine this by looking at:

  • the overall number of plates they got right
  • the colors and given answers for the plates they got wrong
  • the plates that they had more trouble seeing than others or needed to trace with a finger

Red-green color blindness

This is the most common type of color blindness. If a person has red-green color blindness, they may see different numbers in the Ishihara test than the correct answers.

For some plates, a person with this condition may not be able to make out the number or shape, or need to trace it with their finger.

There are several types of red-green color blindness:

  • deuteranomaly, which makes green look more like red
  • protanomaly, which makes red look more like green and makes red less bright
  • protanopia and deuteranopia, which make it impossible to tell the difference between green and red

Blue-yellow color blindness

This form of color blindness is less common. It has two subtypes.

Tritanomaly makes it difficult to tell the difference between blue and green, as well as yellow and red.

Tritanopia causes difficulty telling the difference between:

  • blue and green
  • yellow and pink
  • purple and red

Complete color blindness

Complete color blindness is uncommon. People with this condition can only see shades of gray. They may also have difficulty seeing clearly or sensitivity to light.

The Ishihara test is not the only method of diagnosing color blindness. If the results are not clear, or a person may have a rarer type of color blindness, a doctor may use another test, which could include:

  • Anomaloscope test: This test involves looking into a device known as an amaloscope, which resembles a microscope. A person looks into the eyepiece at two lights, each with a different level of brightness. They then use a dial to adjust the brightness so that both lights are the same. If a person struggles with this, they may have color blindness.
  • Hue test: This involves looking at blocks of colors in different hues. To do the test, a person has to arrange the blocks into rainbow order, starting with red on the left and purple on the right. If a person cannot put the colors in the right order, they might have color blindness.

If a person thinks they may have color blindness, they should speak with a doctor for a firm diagnosis. They may also want to ask some questions, such as:

  • Do you think I should have a color blindness test?
  • How soon can I have the test?
  • How conclusive are the results?
  • Which type of color blindness do I have?

If the person also has other symptoms, such as blurry vision or light sensitivity, they should also mention this to the doctor.

There is no cure for color blindness that a person has had from birth. Instead, treatment consists of using tools to help with distinguishing colors. Some examples include:

  • special glasses or contact lenses that help with differentiating color
  • mobile apps that tell a person what color something is
  • computer software that makes it easier to distinguish between colors
  • adequate lighting indoors, as this can help people with mild color blindness see better

However, the most common types of color blindness are often mild. They may not interfere with daily activities, meaning a person may not need much support.

Depending on the severity, color blindness may affect a person’s ability to:

  • read labels
  • choose matching clothes
  • identify if fruit is ripe or if meat is fully cooked
  • read safety or warning signs
  • participate in certain school-based learning activities

Color blindness can also affect a person’s choice of career and hobbies. For example, a person may not be able to pursue a career that requires accurate color perception, such as a pilot, train driver, or air traffic controller.

People can let teachers, employers, and family members know they are color blind and explain the assistance they might need. Usually, color blindness does not prevent a person from driving.

If color blindness is possibly the result of something else, such as a medication side effect, a doctor may be able to treat the underlying cause.

Online color blindness tests, such as the Ishihara test, can suggest if a person has a type of color blindness. It may reveal difficulty distinguishing between two colors or in rarer cases, complete color blindness.

A person cannot reliably diagnose themselves with color blindness. If a person believes they may have this condition, they should speak with a doctor. This is especially important if a person has vision changes they have never experienced or noticed before.