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  • Writer's pictureMaria Cholakova

Colorblind Tests and Diagnosing Color Blindness

Despite its prevalence, color blindness often goes undiagnosed until it starts interfering with daily functions. Colorblind tests have become essential tools in diagnosing this condition. Learn about the various types of testing available, their accuracy, and how they aid in diagnosing color perception problems.

Diagnosing Color Blindness with Colorblind Tests

Diagnosing color blindness involves a series of tests conducted by an eye doctor.

The most common diagnostic tests are the Ishihara test, anomaloscope examination, and a hue test.

1. Ishihara Colorblind Test

The Ishihara test is the most widely used test for red-green color blindness (Daltonism).

The test consists of plates with colored dots in various patterns. Numbers (for adults) or shapes (for kids) are embedded within these patterns. The goal of the test is to see which numbers/shapes the examined person can distinguish.

The first plate shown to the patient is a control plate. It should be visible to everyone regardless of color vision status.

For the next few plates, people with red-green color blindness may see different numbers or no numbers at all compared to those with regular color perception!

Some of the Ishihata test samples are transformation plates. They show one number to individuals with normal color vision and another number to those with red-green color blindness.

There are also vanishing plates. Vanishing plates show a number to people with color vision which those with red-green color blindness cannot see.

Another "trick" of the Ishihara test is the hidden digit plates. These plates reveal a number only to the red-green colorblind. Those with normal color vision cannot see a clear number.

By the end of the test, the examiner has a clear view of the patient's red and green color-distinguishing capabilities. So the eye doctor can give or dismiss a Daltonism diagnosis.

For other types of color blindness, the patient may need to undergo additional tests.

2. Farnsworth-Munsell 100 Hue Test

example of Hue Test for colorblindness
Example color tubes of an online Hue Test

This test involves arranging colored caps in order of hue.

The Farnsworth-Munsell 100 Hue Test is another method to evaluate color vision deficiencies. But unlike other methods, it is particularly useful for diagnosing subtle and more complex forms of color blindness.

It helps in assessing a person's ability to discern slight variations in color hues.

The test includes four trays, containing a series of small colored caps, each with a slightly different hue.

The patient starts to arrange the caps in each tray in a sequence, which represents a gradual transition of color hues from one end of the tray to the other.

At the end of the Farnsworth-Munsell 100 Hue Test, the sequence is compared to the correct order.

Errors in arranging the caps indicate the presence, severity, and type of color vision deficiency. Specific patterns of mistakes correlate with different types of color blindness.

The test provides a detailed assessment of hue discrimination. It identifies color vision deficiencies other tests might not detect.

3. Anomaloscope Colorblind Test

Example of anomaloscope color matching test
Example of anomaloscope color matching test

An anomaloscope is a device used to diagnose the common red-green color blindness. The test measures how well a person can match different colors. It helps determine the type and severity of color vision deficiency.

The anomaloscope examination is quick, effective, and non-painful.

At the beginning of the colorblind test, the patient looks into an eyepiece. There they see two separate fields of light.

One field displays a fixed yellow light, while the other field allows the patient to adjust the mixture of red and green lights until it matches the yellow field.

The patient uses controls to change the intensity and ratio of the red and green lights to achieve a perceived match with the fixed yellow light.

The way a patient adjusts the colors and the accuracy of their matches indicate the presence and type of color blindness.

For example, individuals with protanopia or deuteranopia will have different matching patterns compared to those with normal color vision.

The results help determine the type and severity of the color blindness.

In summary...

Colorblind tests not only help in diagnosing color blindness but also assist in tailoring coping strategies for those affected. If you suspect that you or someone you know is colorblind, try the abovementioned colorblind tests online and if the results suggest abnormal color perception, schedule an eye doctor's appointment.

There are many coping strategies for the colorblind to make life a bit easier.

Checked by Atanas Bogoev, MD.


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