Color Blindness: Causes, Types, Treatment

Written By: Susannah Lockett

What is commonly called color blindness is a misnomer. Although people with color perception disorders have trouble seeing specific colors, they’re not entirely unable to see other colors.

The only actual exception is an inherited, rare condition called monochromacy. It affects about three persons per 100,000. These unfortunate individuals see the world in only black and white, making daily life a real chore in countless ways. 

Color blindness typically does not cause any type of eye pain or discomfort.

Why is Color Blindness More Common in Men?

Looking at all forms of color blindness, the incidence in men is far higher, about 8 percent for men and only about .5 percent for women. This reflects the genetic cause of some types of red-green color blindness. 

Because the gene involved is located on the X chromosome, males who inherit the faulty gene have this type of color blindness. This is because males have only one X chromosome, which is always passed down from their mothers, and one Y chromosome passed down from their fathers. 

Males with one wrong X chromosome do not have another to take over the functions of the one dysfunctional X chromosome they do have. 

Females, who have two X chromosomes, are typically unaffected if they have a faulty gene on one of their chromosomes. This is because their other X chromosome will compensate. This is also why other X-linked genetic diseases, such as hemophilia, are so rare in females. 

How Do We See Colors?

Color blindness, while often inherited, can also be acquired. There are seven different types of the inherited condition. One is monochromacy. Of the six remaining, four involve red and green colors, and two involve blue and yellow. 

Before describing the different color blindness types, it’s crucial to understand how and why humans see colors. Vision is possible because we have a light-sensitive membrane at the back of the eye called the retina. Light enters the eye and lands on the retina, which has cells called rods and cones. 

The rod-shaped cells are responsible for black and white vision. They are highly sensitive to all degrees of light. Along with the pupil dilating to let in more light, the retina’s rod cells are why your eyes adjust and can see at least basic shapes even in very dim light. Humans have about 18 times more rod cells than cone cells. 

Contrary to popular belief, cats can’t see in total darkness any better than we can. They do have superior low-light vision compared to humans, but no human or animal can see in the complete absence of any light at all. 

The cone-shaped cells give us detail and color vision. They need light to work correctly, which is why colors are vastly dimmed or even absent in very low light. This information will be discussing the cones in greater detail because all forms of color blindness involve the cone cells.

Three Different Types of Cones

People have S cones for blue colors, M cones for green, and L cones for red. All colors humans can see are produced from just these three kinds of cells. Defects in the cones or the absence of them cause color blindness. 

Most people are trichromats, meaning their three essential cones work correctly, and they can see colors. 

All kinds of color blindness are classified as being either red-green or blue-yellow. You already know the primary colors we all learned in grade school: red, blue, and yellow. 

Color blindness is further identified as being either inherited or acquired. An acquired disorder is one not related to genetic causes. 

Inherited Color Blindness

Most types of color blindness have a genetic cause.

Anomalous Trichromacy

This is a spectrum of red-green color vision disorders with four subtypes:

-Protanopia, meaning red-blind
-protanomaly or red-weak, meaning the person has limited red vision but can see some of it
 -deuteranopia, where the person has no green cones 
-deuteranomaly or green-weak, meaning there is some function of green cones, but it’s not normal. 

People with this group of color perception disorders see the world in hues of muted or murky green with some shades of blue and yellow. These people confuse browns, reds, and oranges and typically have trouble seeing pale hues at all. These disorders are the most common types of color blindness. 


Tritanopia means the person has no blue cones, while tritanomaly means they have blue cones, but their function is abnormal. Still, most people with tritanomaly can still see some shades of blue. 


Up to 12 percent of all females inherit this condition giving them a fourth cone, sometimes called “super color vision.” These women can see as many as 100 times more colors than someone with normal color vision!


Acquired Color Blindness

If not genetic, then color blindness is said to be acquired. There are many causes of acquired color blindness:


This may result from the eye’s lens becoming less transparent as it ages, allowing less light to reach the retina. 


This may have a toxic effect on the eye’s color cones, especially the blue-yellow ones.


Carbon disulfide, a flammable, malodorous, and neurotoxic chemical used in some industry types, is known to cause color blindness. The same is true of lead. Both substances are highly toxic, even at low levels. 

Brain injury

Although rare, head trauma and stroke may lead to color blindness.

Chronic illnesses

Alzheimer’s, Parkinson’s, and leukemia are examples of chronic diseases possibly associated with some types of color blindness. 

Most individuals with acquired forms of color blindness retain at least a limited ability to see colors. However, the condition may progress into much more severe kinds of color blindness, even monochromatism. 

The Incidence of Color Blindness

Color blindness is an eye disorder more commonly found in Caucasian populations. The deuteranomalous or green-weak type is by far the most prevalent at 62.5 percent. Red-blind, red-weak, and green-blind all lag far behind at 12.5 percent each. 

Blue-yellow types of color blindness involve much more rare kinds of the condition, some of which affect only about one in 10,000 persons. However, these types also affect males and females equally, unlike the red-green types so much more common in males. 


There are no medical treatments for color blindness in humans at this time. Treatments for inherited types of the condition will likely require advancements in gene therapy not currently available. 

Some types of acquired color blindness may be amenable to improvement by treating the underlying cause, but this would vary by person and the cause. 

Help from Technology

A corrective eyeglass lens called the EnChroma works by increasing color contrast, but results have been mixed. While the manufacturer promotes miraculous color vision with their device, eye care professionals are more guarded about the use of EnChroma. 

This is because success will significantly depend on the individual and their exact type of color blindness. In fact, one study found the EnChroma lens no more effective than high-contrast hunting glasses costing far less. 

Help from Apps

Many apps may help with color blindness:

Color Blind Pal: This basically analyzes colors. It has graphs for saturation, hue, and value. It features overlay patterns and may help the user with color differentiation. 

Dalton Lens: This is specifically for graphs and charts. The app allows the user to hover over a color and get a full description. Color filters help the user to tell different colors and shades of colors apart. 

Sim Daltonism: This one is more for people who are not color blind to help others who are. For example, the app can show you what the world looks like for someone with total red blindness or green-weakness color blindness. 

This helps employers create color-blind friendly workspaces and help website developers design websites usable by color-blind people. 

Color-Blindness in the Workplace

Many careers are not an option for color-blind people: Law enforcement, military, firefighter, and aviator jobs are only a few examples. Interior design, fashion, textile manufacture, and pharmacy are other career choices not suitable for someone with color blindness. 

Many medical careers would also be impossible since color is vital in many medical diagnoses, test results, and interpretations. 

Employers should be aware even in other fields that as many as 10 percent of their employees may have some degree of color blindness and be prepared to accommodate these employees whenever possible. 

Find a Top Eye Doctor Near You

If you’re looking for the perfect eye care professional for an eye exam or because you think you may have an eye condition or disorder, we’re here to help. Our highly-trained doctors can prescribe any vision correction you may need and diagnose and treat any type of eye health condition. 

Our doctors can also test you for color blindness. Treatments to improve your quality of life may be available for your type of color blindness. Schedule an eye exam today or visit our home page for more information.

Published on: Nov 5, 2021
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