Color blindness is a condition in which a person has difficulty distinguishing between certain colors or perceives them differently than most people. It is usually an inherited condition, although it can also be caused by certain eye diseases, injuries, or medications.

The most common type of color blindness is red-green color blindness, which affects the ability to distinguish between red and green colors. This is caused by an inherited deficiency in the light-sensitive pigments in the cones of the retina, which are the cells responsible for color vision. Other types of color blindness include blue-yellow color blindness and complete color blindness (achromatopsia), which is very rare.

Color blindness can cause difficulties in everyday life, such as problems with traffic signals, color-coded maps, and identifying ripe fruits or vegetables. However, many people with color blindness are able to compensate by using other visual cues or by memorizing the positions of colors.

There is no cure for color blindness, but there are some tools and technologies that can help people with the condition. For example, there are specialized glasses and contact lenses that can enhance color vision or improve color discrimination. There are also smartphone apps that can help identify colors or assist with tasks such as distinguishing between red and green traffic lights.

While color blindness can be a challenge, it is typically not a serious or life-threatening condition. It is important for people with color blindness to inform their healthcare provider, as well as their employer or school, to ensure appropriate accommodations are in place if needed.

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 are normal, you perceive color. But if your cones lack one or more wavelength-sensitive chemicals, you will be unable to distinguish the colors red, green or blue.

Color blindness has several causes:

• Inherited disorder. Inherited color deficiencies are much more common in males than in females. The most common color deficiency is red-green, with blue-yellow deficiency being much less common. It is rare to have no color vision at all.
• You can inherit a mild, moderate or severe degree of the disorder. Inherited color deficiencies usually affect both eyes, and the severity doesn't change over your lifetime.
• Diseases. Some conditions that can cause color deficits are 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 deficit may get better if the underlying disease can be treated.
• Certain medications. Some medications can alter color vision, such as some drugs that treat certain autoimmune diseases, heart problems, high blood pressure, erectile dysfunction, infections, nervous disorders and psychological problems.
• Aging. Your ability to see colors deteriorates slowly as you age.
• Chemicals. Exposure to some chemicals in the workplace, such as carbon disulfide and fertilizers, may cause loss of color vision.

There are no treatments for most types of color vision difficulties, unless the color vision problem is related to the use of certain medicines or eye conditions. Discontinuing the medication causing your vision problem or treating the underlying eye disease may result in better color vision.

Wearing a colored filter over eyeglasses or a colored contact lens may enhance your perception of contrast between the confused colors. But such lenses won't improve your ability to see all colors.

Potential future treatments

Some rare retinal disorders associated with color deficiency could possibly be modified with gene replacement techniques. These treatments are under study and might become available in the future.