Color Blindness

Color blindness (color vision deficiency) is what happens when you see colors differently than usual. It’s a fairly common vision issue, especially in males.

Your vision is a complex process that happens when your eyes and brain work together to translate light into the images you see. Special nerve cells in your retinas called photoreceptors turn light into nerve signals your brain uses to create your vision.

Cones (one type of photoreceptor) help you see and tell colors apart. Even though it doesn’t look like it, light is made of tiny, colored waves. There are three types of cones that each sense a different color (wavelength) of light:

• Red-sensing cones (L cones)
• Green-sensing cones (M cones)
• Blue-sensing cones (S cones)

Usually, your eyes use all three cones to sense and put together information that tells your brain what color something is. They use each of these colors together to make every other possible color. Color vision deficiency happens when you’re born without enough cones, or they don’t work like they should.

Most people are familiar with the idea of color blindness. But this is a bit of an outdated term. Color vision deficiency is more accurate. And it’s probably what your healthcare provider or eye doctor will use when you visit them.

Color blindness implies that you can’t see any colors. And that’s not usually correct, even if you have color vision deficiency. Instead, you’ll see some colors differently from most people. Your eye doctor might call this an altered perception of color.

Types of color blindness

There are several types of color vision deficiency. The type you have depends on which of your cones are missing or don’t work properly.

Red-green color deficiency

Red-green color blindness is the most common type. If you have it, you’ll have trouble seeing colors or shades that have red or green. Red-green color deficiency is more common in males. Subtypes include:

• Protanomaly: You have all three cones, but your red-sensing cones don’t work as well as they should. Red may appear as dark gray, and every color that contains red may be less bright.
• Deuteranomaly: You have all three cones, but your green-sensing cones don’t work correctly. You’ll see mostly blues and yellows, and most colors will look muted or softer than they should. Deuteranomaly is the most common subtype of color blindness.
• Protanopia: You’re missing red-sensing cones. You won’t be able to see red. Most colors will look like a shade of blue or gold. You’ll probably have a hard time telling the difference between red and black. Other dark colors (like brown) may look green or orange.
• Deuteranopia: You don’t have green-sensing cones. You’ll mostly see blue and gold. It might be hard to tell the difference between red and green. It might also be hard to tell the difference between green and yellow.

Blue-yellow color deficiency

Blue-yellow color blindness happens when your blue cones are missing or don’t work correctly. It’s rarer than red-green. Subtypes include:

• Tritanopia: Your retinas are missing blue cones. You won’t be able to see any blue. You’ll mostly see red, pink and lavender.
• Tritanomaly: You have all the cones, but the blue-sensing ones don’t work completely. Blues will look green, and you probably won’t be able to see yellows well.

Blue cone monochromacy

This is the rarest type of color vision deficiency. It happens when you’re missing both green- and red-sensing cones. Because your retinas only have blue cones, it will be hard to tell the difference between any colors. Everything might look like a shade of gray.

If you have blue cone monochromacy, you’ll probably have other eye and vision issues, including:

• Amblyopia (lazy eye)
• Light sensitivity
• Nearsightedness
• Uncontrollable eye movements

Rod monochromacy (achromatopsia)

Achromatopsia is when you don’t have any cones. This is true color blindness. You won’t see any colors, and will probably have reduced or low vision and other complications.

Symptoms of color blindness

Not having full color vision is the main symptom. But with most types, it’s more subtle than completely not seeing some colors. If you have color vision deficiency, you might have trouble:

• Telling the difference between certain colors
• Seeing the full brightness or depth of colors
• Seeing shades or variations of the same color

What do people with color blindness see?

It can be hard to notice color vision deficiency, especially if you were born with it. To you, that’s just what colors look like because they always have. You might not know you have it until an eye doctor diagnoses you.

This is especially true in children. Kids probably won’t know or notice anything is off about how they see and understand color. If your child has color vision deficiency, you might notice them:

• Avoiding arts or crafts that require them to use colors
• Using a colored crayon, marker or paint that’s different from what they mean to use (like making the sky green or grass blue)
• Smelling foods before eating them, even if it’s a dish they’ve tasted before
• Struggling to group objects together based on color or how they look

What causes color blindness?

Color vision deficiency is usually something you’re born with (inherited color blindness). It happens because of a genetic change that you inherit from your biological parents. That’s where it gets its name. A genetic change can cause missing or malfunctioning cones that lead to color vision deficiency.

Acquired color blindness happens when you develop it later in life. This happens when something damages your eyes and the cones in your retinas. Some possible causes include:

• Eye conditions like age-related macular degeneration, glaucoma or cataracts
• Conditions that affect your brain or nervous system like diabetes-related retinopathy
• Environmental factors (something about where you live, work or spend a lot of time that damages your eyes)
• Eye injuries or another kind of trauma that damages the connection between your eyes and brain
• Side effects from certain medications

How doctors diagnose color vision deficiency

An eye doctor will diagnose color blindness with an eye exam and vision tests. They’ll examine your eyes and retinas and check your vision. Tell your provider when you first noticed symptoms or thought something might have changed in your color vision.

Color vision tests are quick, in-office tests that will diagnose a specific type and its severity. You’ll look at a series of images on cards or a computer screen and tell your provider what you see.

Your child’s pediatrician will check their eyes during well-baby checkups. They’ll tell you when your child should have their first eye exam.

Are there color blindness treatments?

There aren’t treatments for inherited color vision deficiency. If you have acquired color blindness, there’s a chance your color vision will return after you treat its cause. But the damage in your cones may permanently affect your color vision.

Color blindness glasses can help some people see more colors, or more vivid colors. They might be able to amplify some of your natural color vision. But they can’t treat or cure the cause of color vision deficiency. Ask your eye doctor if they may be a good option for you.

What can I expect if I have color vision deficiency?

Most mild types won’t affect your health or ability to participate in your usual routine. More severe cases (like achromatopsia) can increase your risk of complications and other eye issues.

Talk to your eye doctor about what to expect. They’ll tell you how often you’ll need follow-up eye exams. If your child has color blindness, ask your doctor what you can do to help them with school.