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Color Blindness

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Introduction to What is Color Blindness

The inability of the human eyes in which they won’t be able to perceive red, yellow, blue or green colours, is called the colour blindness. Colour blindness is not any form of blindness but it is the inability or deficiency of the way a person sees colours. Normally, any person who is colour blindness will have trouble seeing one or two colours and they will perceive them in a different way in comparison with the person with normal colour vision. For example, if a person has blue-yellow colour blindness, then they may see these colors red and green.

When any person watches an object, it’s image is being projected on the screen which is called retina and is located at the back of the eyes. Retina is a neural membrane line which is made up of two types of photoreceptor cells which are known as rods and cones. These are responsible for perceiving objects which are in the dark or at night and won't be able to perceive color. Approximately, there are 120 million rods present in each retina. Cones are responsible for perceiving the colors in the presence of light.

Types of Color Blindness

The type of color blindness can be determined by the functioning of the cones. The types of color blindness are as follows –


Any person who is having monochromatism will not be able to distinguish between any color, which is usually because of the absence or total malfunction of the cones present on the retina. A person will be able to distinguish the color objects according to their brightness. This type of blindness is very rare and it occurs usually in the combination with other problems related to vision.


Any person who is having dichromatism usually has two functional types of cones and the third type of cones will be missing or not functioning properly. This results in not perceiving a specific section of the light spectrum to which the missing cones are very sensitive.

Deuteranopia (Green Color Blindness ):

In deuteranopia, the green cone cells which are present in the retina are missing or non functional. When a person is having this particular problem, the mixture of green and red colors are being presented in front of that person and will not be able to make out any difference between those colors.

Tritanopia (Blue Colour Blindness ):

A person with tritanopia is deficient in blue cone cells and is not able to distinguish between the yellow and blue colors. This type of blindness is very rare.


Trichromatism is a type of color blindness in which all the three types of cells function who perceive light and colors, there used to be a shift in the sensitivity of the wavelengths in one of those colors.

Causes of Color Blindness

It can be caused because of chronic diseases like diabetes, etc.

Color blindness can be caused when the medications are being used for a very long time specially those help in the treatment of the nervous disorders. It can also be caused if any accident has happened and which has caused any damage to the eyes or has restricted the supply of the blood to the eyes. Color blindness can be caused because of the age as it is a part of physical changes.

It is mostly caused due to inheritance. It usually comes from parents. The X chromosome carries the gene which is responsible for color blindness. Due to this, men get more affected.

But some severe accidents, illness, and medication can also cause color blindness. The healthy eye retina of humans consists of rod and cone cells. So if these cells fail to perform then it leads to color blindness. If a person’s eyes have no cones or only one cone, it causes monochromacy.

Dichromacy is caused if one type of cone is missing. When all cones are present but not aligned, it causes anomalous trichromacy in these cases. 

How to Check Color Blindness

To measure color blindness in people there are some diagnoses available for them. These tests include the Ishihara plate test and screen testing.

  • Ishihara Plate Testing:

It is considered to be the most common color vision screening. It is a well-known process that is used in schools and also in eye clinics. In this test, a circle is created with two colored irregular dots. Here, the total plate is 38. In this process, patients have to find the total number on the plates

  • Screen Testing:

It determines the types of color blindness one is having. The severity of the syndrome is detected by this testing. 

Treatment of Color Blindness

To date, no cure has been invented for color blindness. One can use glasses or contact lenses that are available with filters, and it helps in curing color deficiencies if necessary. In daily life, people with red and green color blindness can face a few problems like choosing fresh vegetables, fruits, etc. 

Most color-blind people’s vision is normal; all they require is a certain adaptation. People who have this syndrome can follow a properly balanced diet.

Symptoms of Color Blindness

  • The child can have a difficulty in choosing the red and green color crayons or pencils.

  • In coloring activities, the child pays less attention or patience towards it.

  • The child uses the wrong colors in the coloring workbooks.

  • The child denies any decisions which are based on any colors.

  • The child is showing a lack of interest in the activities which are related to color.

  • The color discrimination of the child gets worse when the light is dim.

  • Some children may also have sensitivity to the bright lights.

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FAQs on Color Blindness

1. Is color-blindness common?

Approximately one in twelve men can be affected by color deficiency and in the case of women, the number is one in two hundred women. Worldwide, three hundred million have color blindness. The majority of people inherit color-blindness and some become colorblind in their lifetime due to diseases like diabetes, accidents, etc. Red-green color-blindness is the most common type of it. It really doesn't create any problem in a clear vision for most people. A survey says that color blindness is seen in less than 2% in African- Americans, 6% of Caucasian boys, 3% of Asian and Hispanic boys.

2. How can I pass the Ishihara test?

The Ishihara test is one of the famous tests to check color deficiency syndrome.  This is mainly used for people who are officers, pilots because they need perfection in distinguishing colors. The suggestion is to not cheat in these kinds of tests due to which the real requirement could not be found. During a doctor's examination, a patient should exhibit what he exactly can see. This will help the doctor to find the area of the problem. Other than this, one can challenge the effectiveness of this test by saying that the lantern color blindness method is more realistic than it.