Having color vision deficiency (also called 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 vision deficiency?
The most common kinds of color vision deficiency are genetic, meaning they’re passed down from parents to their children. If your color vision deficiency is genetic, your color vision won’t get any better or worse over time.
You can also get color vision deficiency later in life if you have a disease or injury that affects your eyes or brain.
How do parents pass down color vision deficiency?
Parents can pass down color vision deficiency to their children through genes on chromosomes, which are made of DNA.
Some of these chromosomes — called X and Y chromosomes — are linked to our sex (also called biological sex). Parents pass down the genes for red-green color vision deficiency through the X chromosome. To have red-green color vision deficiency, all X chromosomes must carry the gene for red-green color vision deficiency. This means red-green color vision deficiency is more common in men because:
- Males at birth have only 1 X chromosome from their mother. If that X chromosome has the gene for red-green color vision deficiency, the child will have red-green color vision deficiency.
- Females at birth have 2 X chromosomes, 1 from the mother and 1 from the father. To inherit red-green color vision deficiency, both X chromosomes must carry the gene for red-green color vision deficiency. It’s rare for this to happen.
- Intersex people can have different combinations of X and Y chromosomes. To have red-green color vision deficiency, all of their X chromosomes must have the gene for red-green color vision deficiency. If they have 2 or more X chromosomes, it’s unlikely that all of their X chromosomes would have this gene.
Blue-yellow color vision deficiency and complete color vision deficiency involve other chromosomes, so they affect people of different sexes equally.
What diseases or injuries can cause color vision deficiency?
Color vision deficiency can also happen if your eyes or the part of your brain that helps you see color gets damaged. Common causes of this are:
- Eye diseases — like glaucoma or age-related macular degeneration (AMD)
- Brain and nervous system diseases — like Alzheimer’s or multiple sclerosis (MS)
- Some medicines — like Plaquenil (a rheumatoid arthritis medicine)
- Eye or brain injuries — like retinal detachment and some kinds of tumors
Your color vision may also get worse as you get older, especially if you get cataracts (cloudy areas in the lens of the eye).