How does Ishihara test work?

In old times, there was no proper way of testing the eyes of any person.

Any sightedness was very difficult to detect as there wasn’t any equipment or any method to do so.

Tilsvarende, color blindness also remained undetectable until recent times.

Imidlertid, with the increasing number of cases, it became necessary to invent ways and equipment to counter such problems.

In 1917, a color perception test was designed by a Japanese professor in order to detect the red-green color deficiencies. I

t was named Ishihara test after the professor Dr. Shinobu Ishihara.

Nowadays it’s the most widely used color perception test for such deficiencies.

Working on Ishihara test

It is a color perception test which uses 38 plates in order to detect red-green color deficiencies.

It is also called as ‘38 plates CVD test’. There are several types of plates which are given to the person under test.

Each of the plates consists of a circle of dots which appear to be randomized in color and size.

Some plates contain a number which are visible to the person with normal eyes and invisible or very difficult to the person with red-green color deficiencies.

Other plates contain numbers which are visible to the person with deficient eyes and barely visible to those with normal eyes.

The results extracted from plate observations define the person as normal or deficient.

Normalt, a severe deficiency can be detected after few plates and a little deficiency may require all plates to be categorized accordingly.

I dag, a lot of eye specialists use this test. These tests are also required before the recruitment of army individuals and duty pilots.

Following are some types of plates used during an Ishihara test:

Demonstration Plate

These are designed purposely to be visible for every person whether normal eyed or deficient eyed.

These are for demonstration purposes only and their score doesn’t count.

Transformation Plates

A different color will be visible for a normal person than the color deficient ones.

Both of the groups, control, and test group, will be able to see different figures and numbers.

Vanishing Plates

The figures on these plates will be visible just for the normal eyed persons.

Hidden Digit Plates

The figures on these plates will be visible to only those person having color deficient eyes.

Diagnostic Plates

These are purposely built to detect the severity of deficiency and the type of it.

Get the complete test so you can examine yourself whether you are colorblind or not with the Vision test available at

Lower the score, more deficient the eyes are. Så, anyone who does feel that some colors are confusing for him, he should consult a specialist.

Hvis du har været diagnosticeret med farveblindhed kan du bruge Vision at se alle farverne perfekt.

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