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Different types of colour blindness tests

ishihara colour blind test

A colour blind test checks if you can accurately see colours.  If you cannot pass the test, you have a colour vision deficiency — also calledcolour blindness.

Color blind tests can identify children who might have trouble recognizing colours. 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 perfect colour vision.  

There are two types of colour blind tests:

  1. Screening tests that can detect the presence of a colour vision problem.

  2. More in-depth tests that can detect a colour vision deficiency and measure how severe it is.

Colour blind screening tests

A very popular test for colour 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 colour blindness (the most common colour vision deficiency).

Eye doctors use Ishihara plates to screen patients for colour vision problems. Someone with a red-green colour deficiency 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 colours, brightness and sizes.

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

But someone with red-green colour 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 colour vision.

The complete Ishihara colour blind test contains 38 plates. A shorter version of the test (with fewer plates) may be used during an eye exam to screen for colour 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 talk to you about what this means for you.

In-depth colour blind tests

A screening test may be able to detect colour blindness, but a more detailed colour blind test is needed to measure how severe the condition is.

The most popular in-depth test is the Farnsworth-Munsell 100 Hue Test.

The Farnsworth Munsell 100 Hue test identifies and quantifies colour vision problems. (Image: Macular Pigment Research Group, Waterford Institute of Technology)

This test consists of four trays containing many small disks of varying hues. Each tray has a coloured reference disk at one end.

You must arrange the disks in each tray to create a continuous sequence of colour change.

This test should take place under room lighting that simulates natural daylight.

Each coloured disk has a number on the bottom that enables the tester to compare the results against a key. 

This comparison determines the type and severity of colour blindness.

A shorter version of the Farnsworth-Munsell 100 Hue Test — called the D15 Test — contains 15 coloured disks. Like the Ishihara test, the D15 test is for colour blindness screening only.

Online colour blind tests

Many colour blind tests are available online. Most of these tests are versions or variations of the Ishihara screening test.

Be aware that these online versions may be less accurate, based on the colour accuracy of your display.

For the most accurate colour vision testing, see your eye doctor.

Who should take a colour blind test?

Everyone should take a colour blind test at least once in their lifetime, especially if their job depends on it. 

Excellent colour perception is required for certain technical and manufacturing positions. It's even more important for anyone considering a profession that requires perfect colour vision. Examples include:

  • Commercial artist

  • Marketing professional

  • Designer

  • Electrician

Though there's no cure, people with colour blindness lead full and rewarding lives. Specially tintedcolour blind glasses can help some people see colours more accurately.

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