What is color blindness?

Color blindness is when you see colors differently than most people do.

The retina is the light-sensitive lining in the back part of your eye. It sends visual information to your brain. Your retina has special cells that detect color. These are called cone cells. A normal retina has 3 types of cone cells: green, red, and blue. If you have a problem with any of these types of cone cells, you may have problems seeing colors. But in most cases, the condition will not affect the sharpness of your vision.

The types of color blindness include:

  • Trouble seeing the difference between red and green. The 2 colors look the same. This form of color blindness is common. It occurs much more often in men than in women.
  • Trouble seeing the difference between blue and yellow. This is less common.
  • Seeing only shades of gray. This type is rare.

What causes color blindness?

In most cases, a person is born with color blindness (congenital). But there are types of color blindness that occur later (acquired). These can be more common in older adults.

Color blindness that’s present from birth results from problems with the cones in the retina. This happens because of problems in the genetic information passed from parents to their child. An abnormal gene can cause certain types of cones to develop incorrectly or not develop at all. Problems with the red or green cones are more common than problems with the blue cones.

The most common kind of color blindness is due to a gene problem. The gene is found on the X chromosome. For a man to get this kind of color blindness, he only has to inherit the gene from his mother. For a woman to get color blindness, she must inherit the gene from both her mother and her father. This is why color blindness is much more common in men.

In rare cases, color blindness can be caused by a health condition instead of being present from birth. These include:

  • Optic neuritis
  • Macular degeneration
  • Glaucoma
  • Diabetic retinopathy
  • Multiple sclerosis
  • Parkinson disease
  • Alzheimer disease
  • Other diseases that affect the optic nerve or retina
  • Diseases that affect the lens of the eye
  • Toxic effects from medicines
  • Stroke, especially in the occipital lobe
  • Chronic alcoholism
  • Leukemia
  • Sickle cell anemia

Who is at risk for color blindness?

Having family members with color blindness may increase your risk. Even if you don’t have the condition, you may be at risk of passing it to your children. If the problem runs in your family, ask your healthcare provider about the risks for your children.

What are the symptoms of color blindness?

The most common kind of color blindness is trouble seeing the difference between reds and greens. They may both look gray. Some people may be able to tell the difference between these colors, but only with great difficulty. Others might not be able to tell the difference at all. Depending on the type of problems you have with your cones, your color blindness might be very slight. You may not even know you have it for many years. Other people have red and green color blindness that is more severe. Less often, color blindness causes a problem seeing the difference between blue and yellow. They may look gray.

Most kinds of color blindness don’t affect the sharpness of your vision. Often the only problem is trouble seeing different colors.

If you have a rare and severe form of color blindness, you see only shades of black, white, and gray (achromatopsia). You may also have other symptoms. These include poor sharpness of vision and eye movements that you can't control.

These kinds of color blindness are present from birth. They always affect both eyes. If you have color blindness due to a health condition, your symptoms may get worse slowly over time. They may also affect one eye but not the other. You may find it very hard to pick out dark colors, especially blues.

How is color blindness diagnosed?

An eye care provider can diagnose color blindness with a special eye exam. The exam may use special pictures to see if you can tell the difference between colors. They typically look like circles containing hundreds of dots of different sizes. Some of the dots have a different color than the others. They are arranged to create a number or figure. If your color vision is normal, you will be able to see the number or figure. If your color vision is abnormal, you won't be able to. Your eye care provider may also ask you to use a special device to try to match two colored lights on a screen.

If your eye care provider finds a problem, you may need more detailed color vision tests to find out how severe the problem is.

A color blindness test may be given as part of a standard eye exam. People with mild color blindness might not know they have it. They may find out when they take a screening test for a job that requires seeing colors accurately. Anyone who has a family history of color blindness needs screening.

How is color blindness treated?

Currently there is no cure for color blindness that is present from birth. If you have this condition, you may benefit from special color glasses or tinted contact lenses. They may help you tell the difference between some shades. But they don't give you normal color vision.

If you have acquired color blindness, your healthcare provider will try to address your underlying problem. This can help make the color blindness less severe. Or it can improve the symptoms. In other cases, treatment may help stop the symptoms from getting worse.

Can color blindness be prevented?

There is no way to prevent color blindness that is present at birth. But you may be able to reduce your chance of having color blindness later in life. Get regular eye exams, see your healthcare provider regularly, and follow a healthy lifestyle. These may help reduce your risk for acquired color blindness.

Coping with color blindness

If you are color blind, you may have problems with some common tasks such as:

  • Seeing the difference between ripe and unripe fruit
  • Finding matching items of clothing
  • Seeing if meat is undercooked
  • Telling sporting jerseys apart in a sporting event
  • Seeing information shown in color on graphs or charts

Organizing and labeling objects may help you with some types of tasks. People with color blindness can also learn to focus more on spatial arrangement. For example, the red light is always at the top of a traffic light. There are also many phone apps and devices that can help you decipher between similar colors. It may be helpful for your friends and coworkers to know that you have color blindness.

Some careers may not be an option for people with color blindness. If you are thinking about a career, make sure your color blindness will not be a major problem.

Key points about color blindness

  • Color blindness happens when you can't tell the difference between certain colors in a normal way. And you don't see colors as most people do.
  • This happens because of problems with special cells, called cones, found in the eye.
  • It's often present at birth. Less often, it happens later in life because of a health condition.
  • The most common form of color blindness is having trouble seeing the difference between reds and greens.
  • Currently there is no treatment for color blindness that is present from birth. Special glasses, contextual clues, and organizational strategies may help you cope.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
  • Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.
  • Ask if your condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if you do not take the medicine or have the test or procedure.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.