According to colourblindawareness.org, color blindness or colour vision deficiency affects approximately 1 in every 12 men, and 1 in every 200 women in the world. Though it affects many people, the severity of color blindness varies from person to person, and generally can be categorised into one of several types.

How Many Kinds of Color Blindness Are There? 

There are generally three kinds of color blindness, and they are related to photopigment defects in the three kinds of cones that respond to blue, green, and red light. The most common type of color blindness is red-green color blindness. The second most common is blue-yellow color blindness. The third type, total color blindness, is rare.

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Red-Green Color Blindness 

Red-green color blindness happens when there is a lack of function or loss of function of the red cone (also called the protan) or the green cone (also called the deutran) photopigments.

This kind of color blindness affects individuals differently, because the degree to which their cones aren’t working vary.

For example, some males have Protanomaly, the type of red-green color blindness where the red cone photopigment isn’t normal, while others have Protanopia, where none of the red cone cells work at all.

Others have Deuteranomaly, where the green cone photopigment is abnormal, while others have no working green cone cells at all (Deuteranopia).

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What you see with different kinds of Red-Green Color Blindness:

• If you have Protanomaly, red orange and yellow colors appear greener.
• If you have Protanopia, red looks black and some shades of orange, yellow and green look yellow.
• If you have Deuteranomaly, yellow and green look redder, and you have difficulty distinguishing violet from blue.
• If you have Deuteranopia red colors look brownish yellow, and greens look beige.

Blue-Yellow Color Blindness

Blue-yellow color blindness occurs when the blue-cone photopigments (also known as the tritan) have limited function or are non existent. Just as with red-green colour blindness, blue-yellow colour blindness affects people to vary degrees.

Some people have Tritanomaly, which is the limited functionality of the blue cone cells, while others have Tritanopia, which is the complete lack of blue cone cells.

What you see with different kinds of Red-Green Color Blindness:

• If you have Tritanomaly, blue looks greener, and you have trouble distinguishing yellow from pink.
• If you have Tritanopia, shades of blue appear green and shades of yellow appear violet or grey.

Total Color Blindness

Total color blindness (also known as monochromacy) is very rare and those who have it cannot see colour at all. However, there are two kinds of monochromacy:

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• Cone monochromacy which is caused by a failure of two of the three cone cell photopigments.
• Rod monochromacy or achromatopsia which occurs at birth and is the result of cone cells having no functioning photopigments at all.

The National Eye Institute states that “ People with cone monochromacy have trouble distinguishing colors because the brain needs to compare the signals from different types of cones in order to see color. When only one type of cone works, this comparison isn’t possible. People with blue cone monochromacy, may also have reduced visual acuity, near-sightedness, and uncontrollable eye movements, a condition known as nystagmus.”

What Type of Color Blindness Do I Have?

In order to find out what kind of color blindness you have, you must see an eye care professional, who will perform a spectrum of tests to diagnose you properly.

Common tests include:

• The Ishihara Color Test: This test uses Ishihara plates–plates with different colored circles and dots that create a shape or number. Those with no color blindness will be able to see the shapes or numbers clearly, while those suffering from color blindness will have difficulty seeing the shapes or numbers, or they will not see them at all.

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• The HRR Pseudoisochromatic Color Test: This test uses color plates to test for red-green color blindness as well.
• The Newer Cambridge Color Test: This test is similar to the Ishihara Color Test, except it uses a computer screen, and those who are tested must find the letter “C” which is a different color from the background.
• The Anomaloscope: This test uses different light sources to test for color blindness. Those being tested must try and make two different colored light sources the same using a knob that adjusts brightness and color.
• The Farnsworth-Munsell 100 Hue Test : This test helps discern minor colour differences by hue or shades of the same colour. Those being tested must arrange the colour blocks or pegs in order of hue, usually lightest to darkest. It is most often used to ensure individuals in professions such as digital design, photography or food inspection have pinpoint colour perception.

Is There a Way to Cure Color Blindness?

You cannot cure color blindness, but for some people with red-green color blindness, specially developed lenses can help them see colours more accurately.

There are also many online aids and apps that help those with color blindness distinguish colors from each other for daily tasks, such as matching clothes or selecting ripe fruit.

If you suspect that you might have a form of color blindness, you must book an appointment with an eye care professional to receive an accurate diagnosis. Those affected by color blindness may have difficulty driving, reading and performing a variety of daily tasks without even knowing it.

Having a proper diagnosis will help you find easier ways of managing color blindness if you have it, and give you a better understanding of your condition as well.

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