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Color blindness (color vision deficiency): the signs, the types, who is more likely to have it, the color tests, and what helps
For someone who mixes up red and green, or blue and yellow; for a parent whose child has trouble learning colors, or who has color blindness in the family; for someone whose color vision changed later in life or with a medicine; and for anyone whose job or school work depends on telling colors apart. The National Eye Institute (NEI, part of the NIH) says most people with color vision deficiency are born with it, about 1 in 12 men have it, and most people don’t have problems with everyday activities. This page passes on, by name, what NEI says: the signs, the types, the causes, the tests, and what helps. It builds the words to say to the eye doctor, and prints a card to keep.
Right now
- A sudden change in sight, eye pain, or a lot of new floaters, flashes of light or a shadow like a curtain? That is not something to wait on: go to an eye doctor or an emergency room now, and call 911 in an emergency. A hurt eye: the eye injury page (ours).
- Can’t afford an eye exam? The eye care page lists free and low-cost programs (ours).
- Thoughts of suicide? Call or text 988, any hour (ours).
More help
- Linked to it, on this site: Eyes and sight: find the right page · Eye care you can afford · Cataracts · Glaucoma · Macular degeneration · Retinal detachment · An eye injury.
- School and work: Help at school for your child · Ask for what helps you work.
- Care and costs: When you need a doctor and can’t pay · Get ready for your appointment.
- In a crisis: Help right now (988, 911). All our free tools.
Your eyes or your sight, and not sure this is the right page? The pages on this site for a hurt or pink eye, glaucoma, cataracts, diabetes and the eyes, macular degeneration, a detached retina, dry eye, fading sight and eye care you can afford, on one list.
This page and its wording were written with AI (Claude) for Scarlet Beast (our AI policy). No doctor or nurse has reviewed it. The facts were read on October 16, 2026 on four National Eye Institute (NIH) pages: Color Blindness (last updated November 5, 2025), Types of Color Vision Deficiency (August 7, 2023), Causes of Color Vision Deficiency (January 30, 2025) and Testing for Color Vision Deficiency (December 6, 2024). Ours: that a sudden change in sight, eye pain, or a lot of new floaters, flashes or a curtain is not something to wait on, and 911 in an emergency; that a change in color vision later in life is worth telling an eye doctor about soon; the eye injury page; 988 for thoughts of suicide; not stopping or changing a medicine on your own; telling a teacher; asking for a change at work; that an online dot picture is not the test; what to bring; the questions to ask; low-cost eye exams; and the order of the steps. What we left out: NEI’s research news, and the brand name of the medicine NEI gives as an example. This page saves nothing and loads no trackers.