Having color blindness means you can’t see certain colors the way most people do — or you may not see color at all.

What causes color blindness?

The most common kinds of color blindness are genetic, meaning they’re passed down from parents. If your color blindness is genetic, your color vision will not get any better or worse over time.  

You can also get color blindness later in life if you have a disease or injury that affects your eyes or brain.

How is color blindness passed down from parents?

Conditions like color blindness are passed from parents to their children on groups of genes called chromosomes.

Some of these, called X and Y chromosomes, determine if you are male or female at birth. Males have 1 X chromosome and 1 Y chromosome, and females have 2 X chromosomes. The genes that can give you red-green color blindness are passed down on the X chromosome.

Since it’s passed down on the X chromosome, red-green color blindness is more common in men. This is because:

  • Males have only 1 X chromosome, from their mother. If that X chromosome has the gene for red-green color blindness (instead of a normal X chromosome), they will have red-green color blindness.
  • Females have 2 X chromosomes, one from their mother and one from their father. To have red-green color blindness, both X chromosomes would need to have the gene for red-green color blindness.

Blue-yellow color blindness and complete color blindness are passed down on other chromosomes, so they affect males and females equally.

What diseases or injuries can cause color blindness?

Color blindness can also happen if your eyes or the part of your brain that helps you see color gets damaged. This can be caused by:

  • Eye diseases, like glaucoma or macular degeneration
  • Brain and nervous system diseases, like Alzheimer’s or multiple sclerosis
  • Some medicines, like Plaquenil (a rheumatoid arthritis medicine)
  • Eye or brain injuries

Your color vision may also get worse as you get older, especially if you get a cataract — a cloudy area on your eye.

Last updated: June 26, 2019