Color Blindness: A Comprehensive Guide

If you discover that you do not see and experience colors as well as other people in your life, you may have an eye condition known as color blindness. 

The condition is often genetic. The X chromosome passes it down from generation to generation, making it much more prevalent in boys than girls. About 1 in 12 men have some type of color deficiency. 

Some eye conditions (including glaucoma and cataracts) can cause color blindness symptoms later in life. If your vision changes, visiting your doctor is a smart idea.

What Is Color Blindness?

People with color blindness don’t perceive color in a typical manner. A lack of certain types of cone cells (the cells responsible for color vision) inside the eye is typically to blame.  But some medical conditions can change your vision too. 

Your optometrist can test you for color blindness upon request. There is no cure for color blindness, but several treatment options can improve your quality of life.

Types of Color Blindness 

Three main types of color blindness exist. Understanding what they are, and how they can alter your perception, can help you determine the best solution for you. 

Red-Green Color Blindness

Four subtypes of red-green color blindness exist. They are as follows:

• Deuteranomaly: This is when your green-sensitive cones do not work as well as your red-sensitive ones. You cannot see green well. This is the most common type of color blindness.
• Deuteranopia: This is when you have no cones that can see green light. You cannot tell the difference between green and red. 
• Protanomaly: This occurs when your red-sensitive cones do not work as well as your green-sensitive ones. You cannot see red well.
• Protanopia: This is when you have no cones that can see red light. You cannot tell the difference between red and green.

Blue-Yellow Color Blindness

There are two types of blue-yellow color blindness: 

• Tritanomaly: This occurs when your blue-sensitive cones do not work well. You have difficulty distinguishing between blue and green or red and yellow. 

Tritanopia: This is when you have no cones that can see blue light. You cannot distinguish between blue and green, yellow and pink, or red and purple. You also have difficulty seeing bright colors in general. 

Complete Color Blindness

Everyone sees color a little differently — even people who aren’t color blind.

National Eye Institute

Complete color blindness, or monochromacy, occurs when you cannot see colors. This is the least common type of color blindness. People with this condition see everything in various shades of gray. 

Some kinds of monochromacy also cause additional vision issues like light sensitivity and trouble focusing your vision.

Who Has Color Blindness?

Color blindness is often genetic. If someone in your family has a history of the condition, you’re more likely to face the same difficulties. But the risks rise if you’re male. 

An estimated 1 in 10 men has some form of color blindness, and it’s more common among men of Northern European descent. 

People with medical issues like the following may have an increased risk of developing color blindness later in life:

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

Symptoms of Color Blindness 

The symptoms of color blindness all relate to how you perceive color. People who are color blind may find it difficult to do the following:

• Distinguish between some colors
• See brighter versions of some colors
• Tell the difference between shades of the same color 

If you were born with color blindness, you may not realize you are not seeing the same colors everyone else can see. Many people only begin to suspect that they may be color blind when someone else points out one or more of these symptoms. 

Not all cases of color blindness are equally severe. If your symptoms are mild, you may not notice them for a long time. Some people never notice them.

The Genetics of Color Blindness

Color blindness is usually an inherited condition, meaning that it is caused by a genetic mutation that can be passed from parent to child. Color blindness is much more common in men than women due to the specific genes involved in this condition. 

Among populations with Northern European ancestry, red-green color vision defects occurs in about 1 in 12 males and 1 in 200 females.

National Library of Medicine

Red-green color blindness is passed through the X chromosome, one of the two sex chromosomes in the human genome. A male child has one X chromosome and one Y chromosome, while a female child has two X chromosomes.

This additional X chromosome gives girls some protection against color blindness. If they have one X with the mutation for color blindness, they will only be a carrier for the condition. For girls to be affected, their X chromosomes must carry the mutation for red-green color blindness. It’s only possible if both parents have the mutation. 

However, boys lack a backup X chromosome. If their single X has the mutation for red-green color blindness, the condition will affect them. They only need one involved or carrier parent. 

Blue-yellow color blindness and complete color blindness are passed by chromosomes on different genes unrelated to sex. As a result, they are equally common in men and women. 

Causes of Acquired Color Blindness

While most people with color blindness have the condition due to genetics, some people develop the issue later in life due to disease. 

Eye health conditions like cataracts and glaucoma can interfere with healthy vision and alter your perception of color. For example, cataracts can keep light from entering the eye, while glaucoma can change how well your eyes communicate with your brain. 

Health issues like diabetes and multiple sclerosis can change your vision too. Those problems sometimes improve with proper treatment, but not always. 

Medications can cause color blindness too. The arthritis and lupus medication Plaquenil can cause color blindness in people who use it as the drug can damage your retina. Using the drug for long periods can increase your risk. 

Diagnosing Color Blindness

If you suspect that you may be color-blind, you can ask your eye doctor to test you for the condition. 

First, they will perform a basic eye exam to rule out other conditions. Then, they will administer the following color vision tests: 

• Ishihara test: During the Ishihara test, you will look at images made up of colored dots. A number is hidden in each circle that can only be seen if you can see certain colors. If you cannot tell your eye doctor what that number is, you are likely color blind.
• Color arrangement test: During this test, you will be asked to arrange a set of same-colored objects from lightest to darkest. This test is most useful for determining the severity of your color blindness.

Treating Color Blindness

Color blindness has no cure, but treatment options can make it easier to live with. These are some of them:

• Special glasses or contacts: Corrective eyewear can be made with tinted lenses to help compensate for color blindness. 
• Assistive technology: Computers and mobile devices usually include display options that adjust colors to make them easier for color-blind people to see. Many mobile apps can identify colors for you online and in the real world. 
• Accommodations at school or work: Certain tasks are much more difficult or impossible for color-blind people to accomplish. When these tasks arise, ask for accommodations, such as alternate assignments or work-sharing arrangements.

References

1. Color Blindness. (August 2023). National Eye Institute.

2. Types of Color Vision Deficiency. (August 2023). National Eye Institute.

3. What Is Color Blindness? (September 2022). American Academy of Ophthalmology.

4. Is It True That Colour Blindness Only Affects Boys? Montreal Children’s Hospital.

5. What Is Plaquenil? (April 2023). American Academy of Ophthalmology.

6. Colour Vision Deficiency (Colour Blindness). (March 2023). NHS.

7. Color Vision Devices for Color Vision Deficiency patients: A Systematic Review and Meta‐Analysis. (September 2022). Health Science Reports.