All you need to know about color blindness

If you think color blind people live in a black and white world, you are mistaken! Color blind people also see colors, just not the way normal people do. Let me explain.

How do we see colors?

Before understanding what causes color blindness, let’s understand normal color vision.

Visible light spectrum is composed of seven colors. Yes you guess it right, the seven colors of the rainbow! Violet, Indigo, Blue, Green, Yellow, Orange and Red.

Now our eyes primarily have 3 types of light sensitive cells known as photoreceptors. The “Red” photoreceptors, the “Green” photoreceptors and the “Blue” photoreceptors.

All the colors that we are able to see is due to a combination of these three types of photoreceptors. However when one of more of these are dysfunctional, color blindness develops.

The image below depicts how a person with normal color vision sees colors.

What are the different types of color blindness?

Color blindness is of two types.

1. Red-Green color blindness

People suffering from color blindness are unable to perceive red and green colors. They are however, able to see other colors. Objects of red and green color appear faded.

The medical term for this type of color blindness is “Protanopia”. It’s severity can range from mild to severe.

There is another condition similar to “Protanopia” called as “Deuteranopia” in which the green color vision defect is worse that the red color vision defect.

The image below is an example of what the above image will look like to a person with red-green color blindness.

2. Blue yellow color blindness

People suffering from this type of color blindness are unable to identify blue and yellow colors, while their red color perception is relatively intact.

The medical term for this type of color blindness is “Tritanopia”.

This is a relatively rare type of color blindness.

The image below depicts how a person with blue-yellow color blindness perceives colors.

What causes color blindness?

Color blindness is a genetic condition, that is X linked, which means it will affect males more common that females.

In some cases, people born with normal color vision can later become color blind due to certain diseases of the retina and the optic nerve (the nerve responsible for vision).

How common is color blindness?

You’ll be surprised to know that color blindness is quite common. In India, 8% of males and 1.6% females are color blind.

Color blindness is more common in males because it is an X linked genetic trait.

How can you find out if your have color blindness?

One of the most commonly used tests for colorblindness is Ishihara’s color vision plates.

They were designed by a Japanese scientist Dr. Shinobu Ishihara. They have a specific arrangement of colors, such that a person with normal vision will see a particular number and a color blind person will see a different number. The original test consists of 38 plates, but let’s take a little test with a few plates here.

What number do you see?

If you see the number “74” your color vision is normal. People with red-green color blindness will see the number “21” in this plate.

Let’s try one more plate!

If you see the number “6” your color vision is normal. People with red-green color blindness will not be able to see any number in this plate.

Sounds fun? Let’s try one more!

If you see the number “42” your color vision is normal. Now notice that 4 and 2 in this plate are of slightly different color.

This slight difference is the same as the difference between “Protanopia” (red>green color blindness) and “Deuteranopia” (red<green color="" blindness)

People with “Protanopia” (red>green color blindness) will see only “4” and “Deuteranopia” (red<green color="" blindness)="" will="" see="" only="" "2".

Now let’s come to a really interesting plate!

Can you read a number?

No? Don’t worry! It means your vision is absolutely normal.

People will red green color blindness will be able to see number “5” in this plate.

So this was just a fun test. Why don’t you share this blog with some friends and have them test their color vision too?

To get your color vision fully tested, please visit your eye doctor.

What are the other tests for color vision?

Although Ishihara’s test charts are most widely used, it can detect only red green color blindness. Therefore it is considered as a screening test. Once a color vision abnormality is detected on the Ishihara’s chart, the patient may be advised to undergo detailed color vision evaluation.

Other tests for accurately charting color deficiencies are Nagel’s anomaloscope, Farnsworth Munsell 100 Hue Test and Lantern tests.

Curious what these tests actually are? Follow the links to look them up!

Is there a cure for color blindness?

Unfortunately, no. There is no specific treatment for color blindness. Some types of tinted glasses and contact lenses are available that may help some people identify colors better.

Since color blindness is a genetic defect, some gene therapy based research is going to to find a cure for color blindness.

Why is it important to get yourself tested for color blindness?

Color blindness is quite common and runs in families. If you have color blindness, you may pass it on to your children as well.

A minor color vision defect often goes unnoticed. Although most people with colorblindness lead a normal life, they may face minor difficulties in their daily life due to altered color perception of common items such as fruits, vegetables and other eatables.

Color blindness excludes them from choosing certain professions such as armed forces, pilots, sailors. Children, if diagnosed with color blindness at an early age can be given proper career counselling.

If you have any questions about this post, feel free to drop in a comment below or email me at

I’ll meet you soon in my next blog. Keep adding color to your life with your beautiful eyes and stay healthy!

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