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Surely you have taken a color blind test, whether it was just a game or an in-person test at the doctor. Usually, a color blindness test is done as a condition for entry to college or work. Some occupations do require you not to be color blind. However, do you know how the color blindness test actually works?
What is color blindness?
People with color blindness see colors differently than normal people. If a normal person sees a red object, a color blind person will see the object in another color, perhaps green, blue, yellow, or some other color.
Color blindness occurs because there is an error in the retina. The retina of the eye is responsible for conveying light information obtained by the eye to the brain, so that you can see colors. However, in color blind people there are components of cone cells (cells in the retina that detect color) that are missing or do not function.
You need to know, cone cells are concentrated near the center of vision. There are three types of cones, namely cells to see red, green, and blue. If one of these components is "defective", it will be difficult for a person to distinguish between colors. Usually people with color blindness cannot distinguish certain colors, for example between green and red. Color blindness can range from mild to severe, depending on the problem with the cone cells in the retina.
What is the color blindness test like?
To find out whether you are color blind or not, you are usually faced with a colored image that forms a pattern (like the picture above). This test is called the Ishihara color vision test. You will encounter this test often. As the name implies, the inventor of this test was Shinobu Ishihara, an ophthalmologist from Japan, in 1917.
The Ishihara test is a screening test to detect whether a person has color blindness or not. When running this test, you are usually presented with a book that contains a circular pattern (disk) with many dots of various colors and sizes inside. In one Ishihara book there are usually 14, 24, or 38 images of circles or colored plates. This colored disc is usually called a pseudoisochromatic. The meaning of the term is that the colored dots in the pattern first appear to be the same (iso) in color (chromatic), but the similarity is false (pseudo).
The colored dots in a circle are arranged in such a way that numbers are formed inside. The color of the small dots in the circle is almost similar, so that people with color blindness will mistake the hidden number patterns because it is difficult to distinguish the colors in the image. People with normal eyesight may be able to find the hidden numbers in the circle easily. However, people with color blindness will see different numbers from people with normal vision.
