Overview
Anatomy of the eye
Anatomy of the eye
Your eye is a complex and compact structure measuring about 1 inch (2.5 centimeters) in diameter. It receives millions of pieces of information about the outside world, which are quickly processed by your brain.
Color blindness is an eye condition in which someone can't see the difference between certain colors. Though many people commonly use the term "color blind" for this condition, true color blindness — in which everything is seen in shades of black and white — is rare. The medical term for color blindness is known as color vision deficiency.
Color blindness is usually inherited, meaning it's passed down through families. Men are more likely to be born with color blindness. Most people with color blindness can't tell the difference between certain shades of red and green. Less commonly, people with color blindness can't tell the difference between shades of blue and yellow.
Certain eye diseases and some medicines also can cause color blindness.
Symptoms
You may have a color vision deficiency and not know it. Some people figure out that they or their child has the condition when it causes confusion — such as when there are problems differentiating the colors in a traffic light or interpreting color-coded learning materials.
People affected by color blindness may not be able to distinguish:
- Different shades of red and green.
- Different shades of blue and yellow.
- Any colors.
The most common color deficiency is an inability to see some shades of red and green. Often, a person who is red-green or blue-yellow deficient isn't completely insensitive to both colors. Defects can be mild, moderate or severe.
When to see a doctor
If you suspect you have problems distinguishing certain colors or your color vision changes, see an eye doctor for testing. It's important that children get comprehensive eye exams, including color vision testing, before starting school.
There's no cure for inherited color deficiencies, but if illness or eye disease is the cause, treatment may improve color vision.
Causes
Seeing colors across the light spectrum is a complex process that begins with your eyes' ability to respond to different wavelengths of light.
Light, which contains all color wavelengths, enters your eye through the cornea and passes through the lens and transparent, jellylike tissue in your eye (vitreous humor) to wavelength-sensitive cells (cones) at the back of your eye in the macular area of the retina. The cones are sensitive to short (blue), medium (green) or long (red) wavelengths of light. Chemicals in the cones trigger a reaction and send the wavelength information through your optic nerve to your brain.
If your eyes work as they should, you perceive color. But if your cones don't work properly, you will be unable to distinguish the colors red, green or blue.
Risk factors
Several factors increase the risk of color blindness, including:
- Gender. Colorblindness is much more common in males than in females.
- Family history. Colorblindness is often inherited, meaning it is passed down through families. You can inherit a mild, moderate or severe degree of the condition. Inherited color deficiencies usually affect both eyes, and the severity doesn't change over your lifetime.
- Diseases. Some conditions that can increase the risk of color deficiency include sickle cell anemia, diabetes, macular degeneration, Alzheimer's disease, multiple sclerosis, glaucoma, Parkinson's disease, chronic alcoholism and leukemia. One eye may be more affected than the other, and the color deficiency may get better if the underlying disease can be treated.
- Certain medicines. Some medicines can affect color vision, such as hydrochloroquine, a medicine used to treat rheumatoid arthritis.
- Damage to the eye. Color blindness can be caused by trauma to the eye as a result of injury, surgery, radiation therapy or laser treatment.
Jan. 10, 2025