Understanding Ishihara’s Test for Color Deficiency

Understanding Ishihara’s Test for Color Deficiency

Colorblindness occurs in roughly 1 in 12 men and 1 in 200 women. Color deficiencies often pass down from our parents, rather than developing over time. Even though color blindness is more commonly an inherited condition, many people still live their lives without knowing they have a deficiency at all. Because vision is all about perception, many people with a deficiency do not realize they perceive colors differently than a person with average sight would. Therefore, getting tested for a color deficiency is important. There are many ways to test for a vision deficiency, but the more common method is the Ishihara test. 

Shinobu Ishihara’s Test

Shinobu Ishihara is the creator of the Ishihara test for color deficiency. Ishihara was a professor of Ophthalmology at the University of Tokyo and created the Ishihara test in 1917. The test originally came in three versions, two in Japanese and one in Arabic, to test the vision of soldiers in the Imperial Japanese Army. In later years, the third version of the test, written in Arabic, became widely available in the west. Since then, it has changed numerous times throughout the years to become the test we so often rely on today in color vision testing. 

Understanding Ishihara’s Test for Color Deficiency

If you have ever been to an optometrist, you have most likely encountered the Ishihara test without knowing it. Ishihara’s test relies on 38 numbered plates. Each plate displays a mosaic of dots in different sizes and colors. The image each card makes up is that of a number spelled out in one or two colors, set against a circular background composed of one or two different colors that contrast to varying degrees.

When taking the test, the goal is to identify the number on the plate. A person with perfect color perception would be able to identify all the numbers without issue. Different types of color deficiencies will see different numbers or no numbers at all, depending on the type of deficiency. In this way, this test can also help determine the specific type of deficiency a person may have. 

The Importance of the Plates

As previously mentioned, Ishihara’s test relies on 38 different plates that can help to identify and diagnose color vision deficiencies. However, not all plates have the same purpose. There are many different types of plates used in the test that accurately specify and diagnose a color vision deficiency. There are six different types of plates used in Ishihara’s vision deficiency test.

Each test begins with a demonstration plate. The demonstration plate has a number that is visible to all types of color vision. This plate usually displays the number 12 and functions solely as an example to explain the test to those who are taking it. This plate does not count in the scoring of the test or diagnosis in any way.

Transformation plates are plates where an individual with a color vision deficiency will see a different figure than those with normal color vision, such as seeing the number five instead of the number eight.

A vanishing plate is a plate for which only those with normal color vision can see a figure. For those with a vision deficiency, the plate will look as if it has no visible number in the center.

Hidden digit plates are the opposite of vanishing plates. The figure on a hidden digit plate will only be visible to those who have a color vision deficiency.

Diagnostic plates function specifically to diagnose what type of color vision deficiency an individual has and the severity of the deficiency.

Lastly, tracing plates require individuals to trace a line within the circle rather than identify a number. Someone with a red/green color vision deficiency may not be able to follow and trace a line that uses red and orange colors or shades. 

Should I Get Tested, and Where Should Can I Get Tested?

Many people with colorblindness are still able to function normally within their daily lives, meaning that it’s not as necessary to have regular screening the way one would for the loss of overall vision. However, you should take a color vision deficiency test at least once, if you have not already done so. Luckily, Ishihara’s color vision test is easily accessible. An optometrist can easily diagnose you using the Ishihara testing plates if you suspect you are color blind. Colorblind tests are also widely available online. A simple color blind glasses test online will utilize the Ishihara plates in a digital format. It will ask you to identify the numbers and type in your answer to accurately assess your color vision, negating the need to schedule an appointment and visit a doctor. 

Is There a Cure for Color Blindness?

Currently, there is no cure for colorblindness. However, color blindness is a condition that many people have with little disruption, thanks to a few tips and tricks. Labeling items, such as clothing and heavily color-coded objects like school supplies or work materials, can limit color deficiency-related mistakes in your daily life. Colorblind corrective glasses are another great solution for individuals with a color deficiency. Color-correcting glasses use a filter to cut out the confusing overlapping wavelengths of light that make their way to our brains and cause color blindness. The filter will negate overlap and allow for normal color vision. These glasses give individuals with a color vision deficiency the ability to see in perfect color and are the best solution to color blindness available today. 

Color vision deficiencies present themselves in many different ways and can often go unnoticed by those experiencing them. Shinobu Ishihara’s test for color vision deficiencies, known as the Ishihara test, is one of the most common ways to diagnose color vision deficiencies. While you’ve most likely seen this test before, you may not have understood Ishihara’s test for color deficiency. The Ishihara test's unique use of tactfully color-coded plates allows for the identification of a color-blind deficiency and the diagnosis of the specific colorblindness at hand. 

Ishihara’s Test for Color Deficiency