What Is Color Blindness? Types, Causes and How It’s Tested

Ask most people what color blindness means, and they picture a world in black and white, like an old movie. That picture is almost always wrong. Most people with color blindness see plenty of color. They just see some colors differently, or have trouble telling a few shades apart. A stoplight still looks like a stoplight. A sunset is still beautiful.

The medical name is color vision deficiency. It’s common, especially in men. Most people are born with it, and it stays the same their whole life. But color vision can also change later on, from eye disease, aging or certain medicines. That kind is worth paying attention to, because it can be a sign of a problem that needs care.

This guide clears up the myths, explains the types, shares tips for everyday life, and tells you when a change in how you see color means it’s time for an eye exam.

Key Takeaways

• Color blindness usually means trouble telling certain colors apart, not seeing in black and white.
• Red-green color blindness is the most common type. It’s passed down in families.
• It’s much more common in men. The National Eye Institute (NEI) says about 1 in 12 men have it.
• The kind you’re born with has no cure, but it doesn’t get worse, and there are good ways to cope.
• Color vision that changes later in life can be a sign of an eye or health problem.
• A quick, painless test with colored dots can show if you have it.

What Is Color Blindness?

Color blindness is when your eyes don’t see certain colors the way most people do. The name is a little misleading. Seeing only shades of gray is very rare. Most people with color blindness see a colorful world. They just mix up certain pairs of colors, most often reds and greens, and sometimes blues and yellows.

If you’re born with it, you haven’t lost anything. It’s simply how you’ve always seen. Many people go years without knowing. Then one day they mix up crayons, argue over whether a shirt is green or brown, or don’t pass a color test for a job. It’s not a disease, and it usually doesn’t get worse.

How Color Vision Works

At the back of your eye is the retina (a thin layer that senses light, like the film in a camera). It’s packed with tiny cells that pick up light. Some, called rods, help you see in dim light, but they don’t see color. Others, called cones, handle color.

You have three kinds of cones. One picks up red light, one picks up green and one picks up blue. Your brain mixes their signals into every color you see, a lot like mixing three paints to make any shade. Learn more in our guide: Parts of the eye.

Color blindness happens when one kind of cone is missing or doesn’t work quite right. When the red or green cones are off, red and green start to look alike. When the blue cones are off, blues and yellows are harder to tell apart.

Types of Color Blindness

Red-green color blindness

This is by far the most common type. Reds, greens, browns and oranges can look alike. A red apple might look brownish. It’s the type most often passed down in families.

Blue-yellow color blindness

This type is less common. It makes it hard to tell blue from green, and yellow from red or pink. It comes from a problem with the blue cones.

Complete color blindness

This is rare. It’s called monochromacy (seeing little or no color, only shades of gray). People with it often have other vision problems too, like trouble with bright light and less sharp vision.

Each type can be mild or strong. Some people never notice. Others find many everyday color tasks hard.

What Causes Color Blindness?

Born with it

Most color blindness is passed down from parents through genes on the X chromosome (one of the two chromosomes that decide if a baby is a boy or a girl). Men have one X chromosome, so one copy of the gene is enough to cause it. Women have two, so both would need the gene, which is rare. That’s why it’s much more common in men. Women more often carry the gene without being color blind, and can pass it to their sons.

Color blindness you’re born with affects both eyes the same way and stays the same over time. It isn’t a sign of eye disease.

Develops later in life

Color vision can also change as an adult. The NEI says this can happen with a disease or injury that affects your eyes or brain. Causes include:

• Eye diseases like glaucoma (damage to the nerve at the back of the eye) and macular degeneration (damage to the center of the retina)
• Aging, especially with cataracts (a cloudy lens inside the eye)
• Some medicines, like hydroxychloroquine (Plaquenil), a medicine used for rheumatoid arthritis
• Diseases of the brain and nerves, like Alzheimer’s disease and multiple sclerosis
• An injury to the retina, the optic nerve or the brain

This kind may affect one eye more than the other, and it can change over time. If your color vision changes, have your eyes checked.

Colors Look Faded? Pay Attention

If you were born with color blindness, nothing changes. But if colors that used to look bright now look dull, washed out or yellowed, or if one eye sees colors differently from the other, that’s new. It’s your eyes telling you something.

Signs You Might Be Color Blind

• Trouble telling red and green apart, or mixing them up with brown
• Trouble telling shades like blue and purple apart
• Often disagreeing with others about what color something is
• Trouble reading color-coded charts, maps or graphs
• A child who names colors wrong or has trouble with color lessons
• Trouble with color tasks, like telling if meat is cooked

Because the inherited kind has always been there, many adults first find out during a screening for a job or the military.

How Color Blindness Is Tested

Testing is quick and painless. The most common test uses circles filled with colored dots. Hidden inside is a number or shape made of dots in a different color. If you can see it easily, your color vision is normal in that range. If you can’t, you may have a color vision deficiency. These are called Ishihara color plates.

If that first test shows a problem, your eye doctor can do more detailed testing. One thing to know: the American Academy of Ophthalmology (AAO) says color testing isn’t part of most routine eye exams. So if you’re wondering about your color vision, ask for it.

For children, schools often do a simple color screening. If you have questions about your child’s color vision, ask your child’s doctor or a children’s eye doctor.

Living and Working With Color Blindness

Color blindness isn’t dangerous, and most people adjust so well they barely think about it. A few tips make daily life easier:

• Learn the order, not the color. Traffic lights are in the same order every time: red on top, green on the bottom.
• Use apps. Phone apps can name colors through your camera. That helps with clothes, cooking and shopping.
• Look for labels, not just color. Pick charts, maps and tools that also use words, patterns or symbols.
• Use a system. Label clothes or keep them in an order you know.
• Ask about special glasses or contact lenses. The NEI says they may help some people see the difference between colors. They don’t cure color blindness, and they don’t work for everyone.
• Tell people when it helps. Teachers, coworkers and family can avoid using color alone.

Color blindness can rule out a few jobs that need exact color judgment, like some jobs in flying, electrical work or the military. Almost every other job and activity is wide open.

When Should You See an Eye Doctor?

See an eye doctor if you think you’re color blind and want to know for sure. More important, get your eyes checked if your color vision changes, if colors suddenly look washed out, or if one eye sees color differently than the other. Those changes can come from glaucoma, macular degeneration, a medicine or a problem with the optic nerve, so they deserve prompt attention.

Even if your color vision hasn’t changed, regular eye exams help find these problems early, often before you notice anything.

Frequently Asked Questions

Do color blind people see only in black and white?

Almost never. Seeing only shades of gray is very rare. Most people with color blindness see color well but have trouble telling certain shades apart, most often reds and greens.

Why are men more likely to be color blind?

The genes for red-green color vision are on the X chromosome. Men have only one X, so one copy of the gene is enough. Women have two, so both would need it, which is rare.

Can color blindness be cured?

Color blindness you’re born with has no cure, but it doesn’t get worse, and most people adjust easily. Special glasses, contact lenses and phone apps can help with color tasks. If an eye disease or a medicine changed your color vision, an eye doctor can look for the cause and treat it.

Can you become color blind later in life?

Yes. Eye diseases like glaucoma and macular degeneration, cataracts, some medicines, and some brain and nerve diseases can change how you see color. A change like that is worth an eye exam.

Is color blindness a sign of a serious eye problem?

The kind you’re born with isn’t. It’s just how your eyes work. But color vision that changes as an adult can be a sign of an eye disease or another health problem, so get it checked.

Will my children be color blind if I am?

It depends on the type and your family. Red-green color blindness is often passed from a mother who carries the gene to her sons. Your doctor or a genetic counselor can explain your family’s chances.

Do color blind glasses work?

They help some people see the difference between certain colors more clearly. They don’t cure color blindness, and they don’t help everyone. Try them with realistic expectations.

Can color blind people drive?

Most people with color blindness drive safely. Traffic lights are always in the same order, so you can read them by position. A few jobs with strict color rules may be off limits.

Colors Look Different? Let’s Find Out Why

Maybe you’ve always wondered about your color vision. Or maybe colors just don’t look as bright as they used to. Either way, an eye exam can give you real answers. Dr. James Powers and our team can check the health of your eyes and look for what’s behind a change in color vision, at our New Port Richey, Clearwater and St. Petersburg offices.

• New Port Richey — 5413 US Highway 19, New Port Richey, FL 34652
• Clearwater — 2565 Enterprise Rd, Clearwater, FL 33763
• St. Petersburg — 603 7th St S, St. Petersburg, FL 33701

More guides: Glaucoma · Macular degeneration · Dry eye · Parts of the eye

Sources: National Eye Institute, “Color Blindness” and “Causes of Color Vision Deficiency” (nei.nih.gov); American Academy of Ophthalmology, “What Is Color Blindness?” and “How Color Blindness Is Tested” (aao.org).

This article is general information, not medical advice for your eyes. For advice about your own eyes, call us or see your eye doctor.