Must Know Details About Color Blindness

This fairly common condition often goes undiagnosed because you don't realize that you don't see colors the way other people do. However, the color blindness test is simple, it doesn't even require a doctor's visit. Symbols below and enter the numbers  you can see on the test  based on the Ishihara standard  color plate test. You will immediately get a result that will help you if you have problems with color blindness and which colors are more problematic.

A color blind test checks if you can  see colors accurately. If you fail the test, you have some form of color blindness. Most tests for color blindness are screening tests. You can identify color blindness but cannot determine how severe it is. This requires more in-depth color blindness testing. Color blindness tests can identify children who  have trouble seeing colors.

This could be a factor in certain activities at school and at home. These tests can also identify people who may have difficulty in jobs that require excellent color vision. 

Testing someone for color blindness

Someone who is not color blind will clearly see the number "74" here. A person with color blindness may either see "21" or no number at all.

The Ishihara plate test has been in use since 1917. Each plate has an image with dots of different size and color. People will then see different images (most often Arabic numbers). Those with certain types of color blindness will see different numbers from those not affected by color blindness.

Because many young children have not learned numbers yet, other tests have been developed. They use symbols, like a square, a circle or a car instead of numbers.

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.

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.

Plates

The plates make up several different test designs:

Demonstration plates: (plate number one, typically the numeral "12"); designed to be visible by all persons, whether normal or color vision deficient. For demonstration purposes only, and usually not considered in making a score for screening purposes.

Transformation plates: individuals with color vision defect should see a different figure from individuals with normal color vision.

Vanishing plates: only individuals with normal color vision could recognize the figure.Hidden digit plates: only individuals with color vision defect could recognize the figure.

Diagnostic plates: intended to determine the type of color vision defect (protanopia or deuteranopia) and the severity of it.

Tracing plates: instead of reading a number, subjects are asked to trace a visible line across the plateThe numbering and rotation of plates differs between the shortened diagnostic versions of the test and the full 38-plate test.

History

Born in 1879 to a family in Tokyo, Shinobu Ishihara began his education at the Imperial University where he attended on a military scholarship.Ishihara had just completed his graduate studies in ophthalmology in Germany when war broke out in Europe and World War I had begun. While holding a military position related to his field, he was given the task of creating a color blindness test.

Ishihara studied existing tests and combined elements of the Stilling test, named after the German ophthalmologist Jakob Stilling, with the concept of pseudo-isochromaticism to produce an improved, more accurate and easier to use test.

Test procedures

Being a printed plate, the accuracy of the test depends on using the proper lighting to illuminate the page. A "daylight" bulb illuminator is required to give the most accurate results, of around 6000–7000 K temperature (ideal: 6500 K, Color Rendering Index (CRI) >90), and is required for military color vision screening policy. Fluorescent bulbs are often used in school testing, but the color of fluorescent bulbs and their CRI can vary widely.

Fluorescent lighting showed better results and faster recognition speed compared to CFL and LED luminance in trichromats. Incandescent bulbs should not be used, as their low temperature (yellow-color) gives highly inaccurate results, allowing some color vision deficient persons to pass.

Proper testing technique is to give only three seconds per plate for an answer, and not allow coaching, touching or tracing of the numbers by the subject. The test is best given in random sequence, if possible, to reduce the effectiveness of prior memorization of the answers by subjects. Some pseudo-isochromatic plate books have the pages in binders, so the plates may be rearranged periodically to give a random order to the test.

Since its creation, the Ishihara Color Blindness Test has become commonly used worldwide because of its easy use and high accuracy. In recent years, the Ishihara test has become available online in addition to its original paper version. Though both media use the same plates, they require different methods for an accurate diagnosis.

Occupational screening

The United States Navy uses the Ishihara plates (and alternatives) for color vision screening. The current passing score is 12 correct of 14 red/green test plates (not including the demonstration plate). Research has shown that scores below twelve indicate color vision deficiency, and twelve or more correct indicate normal color vision, with 97% sensitivity and 100% specificity.

The sensitivity of the Ishihara test varies by the number of plates allowed to pass, which can vary by institutional policy. Sensitivity also may be influenced by test administration (strength of lighting, time allowed to answer) and testing errors (coaching by administrators, smudges or marks made upon the plates).

Detailed color blind tests

A screening test may be able to detect color blindness, but a more detailed color blind test is needed to measure how severe the condition is. The most popular in-depth color blind test is the Farnsworth-Munsell 100 Hue Test.

This test consists of four trays containing many small disks of varying hues. Each tray has a colored reference disk at one end. You must arrange the disks in each tray to create a continuous sequence of color change. This test should take place under room lighting that simulates natural daylight.

Each colored 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 color blindness.

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

Online color blind tests

Many color blind tests are available online. Most of these tests are versions or variations of the Ishihara screening test for color blindness. Be aware that these online versions may be less accurate, based on the color accuracy of your display. For the most accurate color vision testing, see your eye doctor.

Who should take a color blind test?

Everyone should take a color blind test at least once in their lifetime. Color blind screening tests are especially important for young children. This is because some learning tasks in school may involve color detection or matching.

• Do you need to pass a color vision test for your job or licensing?
• Are you concerned about your results?
• Did you struggle to see several of the numbers?
• Did you find yourself guessing instead of confidently entering the answers?

If the test shows that you may be color blind, and you feel that color blindness is affecting your everyday life, then there is good news for you. Color blindness treatment is available to help you see the full range of colors that other people see and can guarantee the passing of the Ishihara Color Plate Test!

This system has helped thousands of people just like you overcome color blindness and the challenges it can cause. Whether you have known for a long time that you are color blind or just found out using this test, there is a solution. Reach out to our team today to learn more about the ColorCorrection system and how it can help you see colors clearly again.