There are many types of color blindness, not only seeing gray and white

Even though the name is color blind, this visual impairment is not as simple as being able to see only black and white. There are many types of color blindness, ranging from partial to total. Then, what do people who are color blind see?

The ins and outs of the eye, the window to the world

In the eye, there is a retinal layer which has 2 types of cells to capture light, namely rods and cones. Stem cells are very sensitive to light so they are useful when you are in a dim room, whereas cones have better accuracy and also have the useful photopigments to distinguish between colors.

Cone cells have 3 kinds of photopigments that are useful for distinguishing 3 basic colors, namely red, blue, and green. Colors other than the three basic colors are a combination of the three basic colors, such as yellow which is a combination of red and green.

Then, what causes color blindness?

Color blindness is most often caused by genetic disorders that are inherited from parents. In green red color blindness, the gene responsible for color blindness is found on the X chromosome, so that men who only have 1 X chromosome suffer more color blindness than women who have two X chromosomes. Meanwhile, blue and yellow color blindness is an autosomal disorder.

Different types of color blindness have, what they see differently

Color blindness is not as simple as black and white, but there are several types of color blindness based on the type of cone cell disorder and the type of cone cells involved. There are three types of color blindness, namely

• Green red color blindness
• Yellow blue color blindness
• Total color blindness

1. Green-red color blindness

Red or green color blindness red-green color blindness is a type of color blindness that is most often found. This condition is caused by the loss or limitation of the function of the red (protan) or green (deutran) cone cells. There are several types of green color blindness, namely:

• Protanomaly: abnormal red photopigment of cone cells. Red, orange, and yellow look greener.
• Protanopia: the red photopigment of cone cells is not totally functional. The red color will appear as black. Some colors like orange, yellow, and green appear as yellow.
• Deuteranomaly: abnormal green photopigment of cone cells. Green and yellow appear redder, and it is difficult to distinguish between purple and blue.
• Deuteranopia: the cone cell's green photopigment is not totally functional. The red color looks brownish yellow and the green color looks pale brown (beige).

2. Blue yellow color blindness

Type of blue yellow or color blindness blue-yellow color blindness less frequent than green red color blindness. Caused by the blue photopigment (tritan) not functioning or only partially functioning. There are 2 types of blue and yellow color blindness, namely:

• Tritanomaly: limited function of the blue cone cells. The blue color appears greener and it is difficult to distinguish between yellow and red from pink. This type of color blindness is very rare.
• Tritanopia: limited or less blue cone number of cells. Blue looks green and yellow looks like purple. Color blindness is also very rare.

3. Total color blindness

Type of total or color blindness monochromacy make patients completely unable to see color and their visual acuity can also be affected. There are two kinds, namely:

• Conical monochromation: This type of color blindness occurs due to the malfunction of 2 types of cone cells. To be able to see color, it takes at least 2 types of cones so that the brain can compare 2 different kinds of signals. If only 1 type of cone cell works, the comparison process does not work so that the color is not visible. There are 3 types of monochromation depending on the cone cells that are still working, namely red cone cell monochromation, green cone cell monochromation, and blue cone cell monochromation.
• Monochromation of rods: This is the rarest and most severe type of color blindness. In this color blindness, there are no cones at all. There are only stem cells at work so that the world actually appears as black and white and gray. Patients with rod monochromation tend to be uncomfortable when exposed to brightly lit environments.

How do doctors diagnose this type of color blindness?

There are many tests that can be done to check for color blindness, but the most common and easy to do is to use the Ishihara test. A book containing certain pictures and numbers will be shown to the patient and the patient will be asked to read the numbers in the picture. However, the color blindness test developed by a Japanese doctor named dr. This Shinobu Ishihara can only be used for red and green color blind examination.