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The Causes of Color Blindness (Can It Be Prevented?)
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Color blindness is an uncommon visual issue that is most often linked to a genetic cause. It affects 1 in 12 men.
The most common form of color blindness is red/green blindness, with blue/yellow being the second most common. Achromatopsia, or total color blindness, is extremely rare.
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Most people who are color blind have this condition for their whole lives and rarely experience other problems. Severe color blindness may have some other impact on your vision.
There might be an underlying disease or trauma that caused color blindness, so if you develop this condition, make an appointment with your ophthalmologist immediately.
Treating color blindness typically involves adjusting to the condition and finding ways to manage daily life. Overall, people who are color blind live normal lives.
What is Color Blindness or Deficiency? An Uncommon Visual Concern
Color blindness describes an incurable condition in which someone cannot see or distinguish the correct tones of colors. The condition usually affects the ability to separate red colors from green colors, although sometimes detecting blue from yellow colors is also an issue.
Medical evidence shows that color blindness is hereditary, and genes passed down from generation to generation is a main cause. Both eyes are usually affected in the same way.
The medical explanation for why color blindness happens starts with cone cells in the retina are not functioning or are not present at all. The normal human body has three of these cone cells, which detect green, red and blue. When one or more of these cells malfunction, color blindness occurs.
However, the condition is not the same for everybody who has it. Some people experience less severe cases of color blindness than others. For instance, some people can see colors fairly well under well-lighted conditions and falter only when light is poor. Some can’t distinguish any colors no matter what the light conditions are.
Severe color blindness happens when all three cone cells are absent. Mild cases come when the three cells exist but one of them does not function.
For those who have severe cases of color blindness, all colors appear the same: gray. This rare condition is called achromatopsia.
Having color blindness does not affect sharpness of sight.
Types of Color Blindness & Associated Issues
Color blindness occurs when certain light-sensitive nerve cells in your eye do not respond to light triggers as normal, so the brain does not interpret these signals as a specific color.
There are two basic types of cells in your retina that detect light: rods and cones. Cones are the cells that comprehend color. Rods interpret light and dark, and they tend to work better in low light or at night.
There are a few types of color blindness.
Red/Green
When one pigment is missing from your cones, you have trouble telling the difference between red and green. This is the most common type of color blindness.
There are sub-types of red/green color blindness, including:
- Deuteranomaly, which makes green look more red.
- Protanomaly, which makes red look duller and more green.
- Protanopia and deuteranopia, in which you cannot tell the difference between red and green at all.
Blue/Yellow
This is a rarer form of color blindness. As with red/green, it involves one missing pigment. People who struggle with yellow and blue also often have red/green color blindness. There are two sub-types of blue/yellow color blindness, including:
- Tritanomaly, which makes it hard to tell the difference between yellow and red, and between blue and green.
- Tritanopia, which is when you cannot tell the difference between blue and green, between purple and red, and between yellow and pink. Reds look duller too.
Achromatopsia
This is total color blindness which is very rare. People with achromatopsia can only see shades of gray.
Sometimes, your color blindness can be so mild, you do not notice it. Many people with mild red/green color blindness do not learn they have this condition until they are specifically tested for it.
Some people have color blindness that is severe enough that they need help navigating the world. They cannot tell the differences in something unless the hues are very different.
If you have very serious color blindness, you may also have symptoms like:
- Nystagmus, or quick side-to-side motions of your eyes due to problems processing images.
- Photosensitivity, or discomfort or pain from bright lights.
- Amblyopia or “lazy eye.”
- Poor visual acuity.
Causes of Color Blindness
The primary cause of color blindness is genetics, and those who have the condition usually had it at birth. It occurs because of a problem with molecules in the retina’s cone-shaped cells. These molecules, called photopigments, are responsible for detecting color. When they lack pigments, you won’t be able to see certain colors.
The genes you inherit from your parents are usually the reason for faulty photopigments. However, color blindness can also occur due to non-genetic reasons. Non-hereditary cases of color blindness occur due to damage to the eye or the part of the brain that perceives color.
You can also experience color blindness because of one or more of these conditions:
Glaucoma
Glaucoma is a medical term for a collection of eye conditions that cause blindness. In all these conditions, the optical nerve suffers enough damage to cause permanent visual impairments.
What happens is that the pressure inside the eye (interocular pressure) grows to be too high, which eventually leads to optic nerve damage.
The optic nerve delivers signals from the eye to the brain. Progressive damage diminishes its ability to communicate visual signals to the brain. Consequently, you can lose your ability to distinguish colors.
Age-Related Macular Degeneration (AMD)
Macular degeneration (AMD) is a common cause of vision loss that comes with age. It’s characterized by a reduction in the center of your field of vision. During the onset of AMD, vision loss is often preceded by a reduction in color perception as the photoreceptors in the cone cells die off. These cells, which are dense in the macula, are a primary means of color vision.
Multiple Sclerosis
People with multiple sclerosis often endure vision problems from time to time. In some cases, color vision deficits stem from demyelination of the optic nerve. In the absence of optic neuritis, parvocellular (red/green) and koniocellular (blue/yellow) pathways are affected, resulting in color deficiency.
Alzheimer’s Disease
Patients with Alzheimer’s discover color issues regardless of how severe their Alzheimer’s is. The neurodegenerative disease impairs cognitive functions and causes visual impairments that affect your contrast sensitivity and motion detection. Along with color blindness, a patient with Alzheimer’s is also likely to suffer from decreased color blindness.
Cataracts
Cataracts cause the eye’s natural lens to become clouded. That immediately causes a problem with color vision, whereby colors become washed out and dull.
Corrective surgery, which may involve the replacement of your natural lens with an artificial intraocular lens, can improve color vision if cataracts are the cause of your color blindness.
Clearing cataracts via LASIK surgery will also restore colors to their original brightness as well as improve the overall sharpness of your vision.
Prescription Medications
Some prescription drugs can cause changes to color vision. Plaquenil (for rheumatoid arthritis), Myambutol (for tuberculosis) and antipsychotic medications such as thioridazine and chlorpromazine tend to cause optic nerve problems that can affect the ability to see some colors.
Substance Abuse
Acquired color blindness can also come from substance abuse. Chemicals in drugs like barbiturates are known to cause nervous disorders and can impact the optic nerve as well. In addition, tobacco-alcohol amblyopia, which manifests as a scotoma (blind spot) that’s central or paracentral to the lens, can cause color vision defects.
Eye and Brain Injuries
Strokes, seizures and traumatic brain and eye injuries can damage the color processing centers and affect vision. When injuries cause issues with the receptor cells in the retina, you can develop color vision deficiencies. Even eye diseases that damage the optic nerve can cause color blindness.
Testing & Treating Color Blindness
Color testing is a common part of most eye exams. If your vision care provider does not offer this as part of the exam, you can request it.
Overall, there is no cure for color blindness, but you can find ways to adjust.
Sometimes, you can use special glasses or contact lenses to distinguish more between colors like red and green. These do not “change” your eyes or improve your vision so you can truly see these colors, but they do change the hues on some colors so you can understand that they are different colors.
If you have color blindness from another cause, like a prescription medication, work with your doctor to manage the condition. You may not be able to recover all of your vision, but in some cases, recovery is possible.
Can It Be Prevented?
If you inherit color blindness from your parents, there’s no way to prevent it. However, it’s possible to reduce the risk of developing color blindness later in life.
Some of the ways to achieve that include:
- Getting regular eye tests. Regular eye exams can help detect eye-related diseases before they affect the optic nerve. Cataracts, for instance, can be detected early and treated or prevented, reducing your likelihood of developing color vision deficiencies.
- Avoiding substance abuse. Alcohol and tobacco are linked to permanent eye damage, one of which is the development of permanent retinal blind spots that can deteriorate to permanent blindness. Substance abuse increases your likelihood of developing color blindness.
- Living a healthy lifestyle. Protecting your eyesight can prevent damage to the retinal cells that carry pigment. Using blue-light filters when watching media devices can also slow down retinal damage and reduce the chances of developing color blindness.
Most types of color vision deficiencies are untreatable. But if your color blindness is brought on by an eye disease or prescription medications, discontinuing the prescription or treating the underlying eye condition can restore your color vision.
It’s important to speak to an eye health expert to understand the causes of your color blindness before choosing a course of action.
References
- Color Blindness. (May 2019). MedlinePlus.
- Types of Color Blindness. (June 2019). National Eye Institute (NEI).
- Color Blindness. (July 2019). National Eye Institute (NEI).
- What Are the Symptoms and Causes of Color Blindness? (September 2019). American Academy of Ophthalmology (AAO).
- Causes of Color Blindness. (June 2019). National Eye Institute
- How Drug Abuse Affects the Eye. (September 2018). Review of Optometry.
- Color Vision. (January 2018). The Brain Recovery Project.
- What Is Color Blindness. (April 2021). American Academy of Ophthalmology.
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