A red-green color blind test detectsred-green color blindness. The most common such test is theIshiharatest.
Red-green color blindness makes it difficult for someone to differentiate between red, green, and yellow. Some people with red-green color blindness may not be aware of their condition.
A red-green color blind test can let such people know that they have this form of color blindness so they can take the necessary precautions to stay safe even when they can’t tell some colors apart.
This article explains red-green color blindness along with why it happens and the tests used to diagnose it.
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Red-Green Color Blindness
Red-green color blindness, also called a red-green vision defect, is the most common type of color blindness, affecting up to 8% of males and 1% of females globally.
This type of colorblindness results from loss or damage to red- or green-sensing photoreceptors in the eye. For people with this form of color blindness, reds and greens look similar to each other, appearing as a brownish, muted tone.
The terms “protan"and “deutran"are often used to refer to red and green color deficiencies, respectively.
That said, there are four subtypes of red-green color blindness:
What Causes Color Blindness?
Color blindness, also known as color vision deficiency, is usually genetic, meaning it is passed on from parents to children. In theretina, light receptor cells calledrodsandconestransmit signals from the eye to the brain. Rods provide vision in low light, while cones provide vision in bright light and color vision.
Some cases of color blindness are acquired. They can arise from diseases involving the retina or areas of the brain involved in processing visual information, as side effects of certain drugs, or from exposure to particular chemicals.
What Do Color Blind People See?
Types of Red-Green Color Blind Tests
Ishihara Test
The test includes the following four types of plates.
The Ishihara test works for most people. However, other tests may be needed in some cases, such as for people whose eyesight is so poor they can’t see any of the image well, regardless of color.The military also uses more specialized testing.
Cambridge Color Test
Combining the principles of the Ishihara test plus new technologies, the Cambridge Color Test uses plates with colored dots like the Ishihara test but the C-shape is a different color than the background. The C-shape, called the target, appears randomly in one of four orientations, and the person taking the test must click on one of four keys to indicate the orientation.
At first, the target includes vivid, bright colors, which help establish the test taker’s reliability in determining the orientation of the C-shape shown. Then, the computer alters the color quality (chromaticity) between the target and background according to the person’s performance. There are longer and shorter versions of this test.
Another version of the Cambridge test used for people with low vision has four plates, but instead of the plates showing dots and a target, they are all of one color. Three of the plates have a neutral, grayish color, and one has a different color. The person taking the test needs to identify the circle with the indicated color.
Lantern Test
D-15 Test
This test involves arranging a set of colored plates or discs in the correct color-coded order (a continuum of gradually changing hue).
It is especially useful in detecting dichromatic vision, a condition in which a person only has two types of functioning color receptors in their eyes. Additionally, this test can help determine the severity of the color blindness.
Richmond Hardy-Rand-Rittler Test
Also called the Richmond HRR, this test is used to check for red-green and blue-yellow color blindness along with color blindness severity. Many consider the Richmond HRR test to be the most advanced color-vision test available, capable of detecting color blindness with approximately 97% accuracy.
Color Vision Testing Made Easy (CVTME)
This color vision test is a less demanding test designed for children as young as 3 years old. The test can be easily adapted for children with intellectual disabilities. CVTME uses pictures made of colored dots that display simple images, like stars, circles, and squares. It is a fun test for children that can be completed within 60 seconds.
Neitz Test of Color Vision
The Neitz Test is a simple, quick, and inexpensive test that can identify the type or severity of color blindness within minutes and under any kind of lighting. The Neitz test is similar to other tests in that it displays colored shapes within grey dot patterns. Under each visual, users mark what shape they see. If no shapes are seen, the user can be considered color blind.
Farnsworth–Munsell 100 Hue Color Vision Test
Originally created in the 1940s, the Farnsworth-Munsell Color Vision test has been made into several variations. For example, the Farnsworth-Munsell 100 Hue Color Vision test features 100 hued tiles, while the Farnsworth-Munsell D15 Color Vision test features just 15. Farnsworth-Munsell tests are available in physical form, but can also be taken online.
Anomalscopes
Who Needs a Color Blindness Test?
The American Optometric Association recommends that all children have a comprehensive optometric examination before beginning school, since a lot of learning materials rely heavily on color perception or color coding.
You may also need a color-blindness test if:
Some diseases can cause color blindness, such as glaucoma, age-related macular degeneration, Alzheimer’s disease, and multiple sclerosis. The rheumatoid arthritis medication Plaquenil is also linked to decreased color vision.
Consider having your vision checked if you have been diagnosed with one of these conditions, or if you experience any changes in your vision or color perception.
How Do I Check If I Am Color-Blind?
If you suspect you may be color-blind, first schedule an appointment with your healthcare provider or an eye specialist (an opthalmologist or optometrist).
You can find versions of the Ishihara color test and many others online. However, it’s important to note that several factors can impact the reliability of the test, including the type of device or monitor you are using and whether it has a blue light filter.
Summary
Most people adjust to red-green color blindness without any serious issues. If you suspect that you may have this form of color blindness, ask your eye doctor for a test. The test you are given may depend on your age or occupation. The final results will help your provider determine the severity of color blindness you have, and whether it is inherited or acquired. It will also help them determine which technologies, if any, will be beneficial for improving your eyesight.
A Word From VerywellAlthough there is no cure for color blindness, there are special glasses or contacts and visual aids that can help people distinguish differences in color better. Fortunately, people with color blindness typically don’t have much trouble with day-to-day activities.—CHRISTINE L. LARSEN, MD, MEDICAL EXPERT BOARD
A Word From Verywell
Although there is no cure for color blindness, there are special glasses or contacts and visual aids that can help people distinguish differences in color better. Fortunately, people with color blindness typically don’t have much trouble with day-to-day activities.—CHRISTINE L. LARSEN, MD, MEDICAL EXPERT BOARD
Although there is no cure for color blindness, there are special glasses or contacts and visual aids that can help people distinguish differences in color better. Fortunately, people with color blindness typically don’t have much trouble with day-to-day activities.
—CHRISTINE L. LARSEN, MD, MEDICAL EXPERT BOARD
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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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