by on December 20, 2022

We must first comprehend how the eye functions to comprehend color blindness. Your eye's front (lens) lets light in, which is focused onto the retina (back of the eye). 

The retina is made up of unique nerve cells called photoreceptors that respond to light with pigments. These are your rods and cones.

Rods respond to all colors of light in the same way; they are irrelevant to your color vision. Rods are very light-sensitive and contribute to our night vision!

Today, we should concentrate on cones. Cone cells come in three different varieties, and they govern your ability to see color. Different light wavelengths cause the pigments in these cone cells to respond as follows:

  1. Short wavelengths (blue)
  2. Medium wavelengths (green)
  3. Long wavelengths (red)

When the pigments in your cone cells don't react properly, color blindness can result (or at all).

What kinds of color blindness are there?

"Color vision deficiency" is another name for color blindness. This is because a lack of cone cells in your eye is what causes color blindness.

Your cones have about 60% red, 30% green, and less than 10% blue sensitivity. Therefore, whether red, green, or blue cone cells are affected will determine which type of color blindness a patient experiences.

1. Red-Green Color Blind

Red-green color blindness is the most well-known type of color deficiency and happens when your red or green cones are damaged. The most prevalent type of color blindness, affecting 8% of men and 0.5% of women, is red-green color blindness. Because your red cones and green cones can malfunction separately, there are multiple types of red-green color blindness.


The most common type of color blindness, this form affects 5% of men. It also goes by the name of deutan color blindness and happens when the green cones don't work properly. Yellow and green appear redder as a result, and blue is challenging to determine from violet.


Red cones don't function properly in protan color blindness. The severity of this kind of color blindness varies. Colors are less vibrant overall and orange, red, and yellow appear greener.


Your red cone cells are completely inoperative. Red and orange and yellow and green just appear to be shades of grey.


The green cone cells don’t work at all. Reds appear brownish-yellow and greens appear to be beige.

2. Blue-Yellow Color Blind

Contrary to red-green color blindness, Tritan color blindness only affects 1 in 10,000 people and equally affects both men and women. Blue-yellow color blindness can be inherited, but it's more likely to develop later in life as a result of glaucoma, cataracts, age-related macular degeneration, retinopathy, or other eye conditions that harm the optic nerve or retina.

There are two varieties of blue-yellow color blindness.


The blue cones' color sensitivity changes in this type of color blindness. People who are Tritan colorblind frequently mix up the colors yellow, orange, and red as well as blue and green.


The blue cones don’t work at all. 

Blindness to all colors

Anomalous trichromacy or dichromacy are the types of color blindness that were previously mentioned. That is, having all three color rods still, but some of them not working or having only two color rods working.

There are, however, more advanced forms of color blindness, such as:

Cone Monochromacy

This occurs when two of the three cone cell pigments don’t work.


A total lack of color vision. Complete achromatopsia restricts vision to black, white, and grey and is frequently accompanied by other vision problems.

What symptoms indicate color blindness?

Depending on the degree of color blindness, different people experience different symptoms. Some people have symptoms that are so mild they aren't even aware they have a color perception deficit. The sharpness of vision is typically unaffected by color blindness. Primary symptoms of color blindness include:

  • Trouble seeing colors or the brightness of colors.
  • Inability to tell the difference between shades of the colors (most commonly with red and green or blue and yellow).

Ask your eye doctor about a color vision test if you think you might be color blind.

Exactly how is color blindness identified?

Children typically undergo a color blindness test as part of a routine eye exam, especially if they are at risk for the condition.

You've probably seen pictures from the Ishihara cooler test, even if you've never taken a color vision test.

The numbers that are concealed in these fields of colored dots can be seen by patients with normal color vision. The numbers will either not be visible to color-blind people or, depending on the image, they will see a different number. This enables the eye doctor to identify the type and degree of color blindness in a patient.

Why It's Important To Test For Color Blindness And How To Do It?

Your optometrist will perform the eye examination while you cover one of your eyes in a well-lit room. They will then offer you a series of test cards that have multiple dots on each. 

These cards will have patterns, letters, or numbers that will be perceived by those who can see the whole color spectrum, but those who struggle to determine the symbols among the dots include people with color vision impairment.

The test will be performed again with the other eye. It is possible to have a color vision deficiency in one eye and not the other. After the eye exam, the eye doctor may ask you questions about your perception of the intensity of the colors.

What causes color blindness?

Men are more prone to developing this condition because it is primarily genetic in origin and is carried on the X chromosome. Approximately 1 in every 12 men has some form of color blindness versus approximately 1 in every 200 women. 

Color blindness may be caused by certain diseases affecting the optic nerve such as glaucoma, damage to the eye or parts of the brain, medications, aging, or exposure to chemicals. Other diseases that can cause color blindness include:

  • Diabetes
  • Alcoholism
  • Macular degeneration
  • Leukemia
  • Alzheimer’s
  • Parkinson’s
  • Sickle cell anemia

If your color blindness is due to any of the diseases listed above, color vision may be restored following treatment for the underlying illness. If color blindness is genetic there is no cure, although there are tinted glasses and contacts available to help correct vision and technological advances are showing promise for the future of color blindness correction.


Q: If color blindness is genetic, is it dominant or recessive?

A: Color blindness is a recessive hereditary trait that is carried on the X chromosome. Women are less likely to be color blind because they would need both of their X chromosomes to be carrying the gene, while men only need the gene on their singular X chromosome.

Q: How old can a child be to get tested for color blindness?

A: Take your child to the optometrist for a color vision test at approximately 4 years old. 

Although children should be going for eye exams before this (starting at about 6 months old), 4 is an appropriate age for a color vision test because the child will be able to communicate what colors they perceive. 

This is also around the time the child will be going to school where many objects for younger children are color coded.

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