The red-green colorblind test, known as Ishihara plates test, can help you find out if you have color blindness or not. It is designed to perform a quick and accurate assessment. This is a test you’ve probably seen before – it has little circles colored in red, green and blue.

What is color blindness?

Color blindness is a color vision deficiency in which a person cannot distinguish a certain color. It is the most common form of color vision disorder and typically it affects more men than women. About 98% of color blind persons have difficulty in distinguishing red and green colors. There are some people who cannot distinguish blue from yellow. The color blindness disorder is also known as dyschromatopsia.

Some people believe that when a person is color blind, he or she cannot see colors. Instead he sees the world in black, white or gray. This is a major misconception although there are some very rare cases. Colorblind people can perform daily tasks effectively as a person with a normal vision.

Red, Green and Blue – the main colors of the light spectrum

Types of color blindness

There are different kinds of color blindness: Protanopia – not recognizable red color, Deuteranopia – not recognizable green color, and Tritanopia – not recognizable blue color.

The most common form is caused by problems with the middle or long wavelength systems. It will have the difficulty of distinguishing red and green. This is often referred as red-green color blindness. Physically acquired color blindness is unlike the normal form and often it is reversible and temporary.

Normal vision




The types of genetically acquired color blindness depend on the severity of the functional loss of one or more of the different cone systems. When only one cone system is damaged, dichromacy results.

Achromatopsia is a rare case of the disability of seeing colors. Although this term can also be used to refer to the other color disorders such as agnosia and cerebral achromatopsia, it is normally congenital color vision disorder such as rod monochramacy and cone monochromacy.

When a person has a color agnosia or a cerebral achromatopsia, he cannot perceive colors even though the eyes are normal. The problem is in the barin’s visual cortex.

Causes, risk factors and prevention

Color blindness is due to a lack of a specific dye in the nerve cells that distinguish colors. The lack of dye in turn is due to genetic reasons. Dyes are light-sensitive chemicals.

The cells that “see” the colors are located in the retina and are called cone cells or cones. Very rarely, color blindness may be due to damage to these cells.

Some diseases and conditions, such as diabetes, glaucoma, Parkinson’s disease, macular degeneration, leukemia, etc., as well as some medications, can cause an inability to see one or another color shade.

About one in 10 men suffers to some degree from color deficiency. The condition is 20 times less common in women than in men.

Symptoms of color blindness

In most cases, the color blindness is mild and we do not notice it. When it interferes, shades of red, green, blue and yellow are usually not visible. A complete color blindness is very rare. The people that have it see only shades of gray.

Red-green color blindness is usually diagnoses through different clinical testing such as the red-green Ishihara plates test. The Ishihara color test has a series of images of red and green circles. A figure usually a number is embedded in the pictures and can be seen with normal eyes. Most assesments are designed to be efficient in identifying broad categories of color blindness. Some types of filters and contact lenses may help a person to observe different colors better.

How do colorblind glasses work?

What is the treatment for color blindness?

In most cases, color blindness is not curable because it is hereditary. It is a lifelong condition. When the condition is due to medication or an illness, removing the cause usually restores vision. In case we do not see certain colors completely, it helps to remember the sequence of colors when it is important, such as at traffic lights.

Types of colorblind tests

There are different types tests and the Ishihara plates red-green colorblind test is the most common. There’s also the HRR test. A lot of clinics are using it because it’s a little bit more specific to what type of color deficiency or color blindness somebody has. There’s even the D15 or the D100 where people put colored circles in order. This can tell us a little bit more about what type of color saturation and hues they’re able to perceive. There’s even special color vision anomaly scopes which are usually in more in University settings, for people with other types of color deficiency or color blindness.



The term daltonism is often used as a synonym for this condition, although it refers to a specific type of color blindness. The term comes from the name of the English chemist John Dalton – the first to describe color blindness and suffer from it himself.

Iodopsin and Rhodopsin

In color blindness, there is a dysfunction of the cones (one of the sensitive cells in the eyes) containing the pigment iodopsin, which is responsible for color perception, while the pigment rhodopsin contained in the rods allows the differentiation of lights and shadows.

Trichromats and dichromats

People which are abnormal trichromats, have slight disturbance in the sensitivity of the cones. In the case of dichromats, there is a partial or complete absence of some of the cones, in which people distinguish only two of the basic colors. Find out if you are dichromat, with the red-green Ishihara colorblind test.

Note: If you experience some of the symptoms of color blindness, we recommend you to asses yourself with the red-green colorblind test. And if you need further assessment, call your doctor.