“Color blindness” is actually a misleading term, the more accurate term is “color vision deficiency.” Nearly everyone can distinguish some colors, but people with color vision deficiency have trouble seeing differences between certain shades of colors. The most common types of color vision deficiencies are with shades of reds and greens. People with normal color vision can distinguish more than 100 different colors. Those with strong color vision deficiencies may only be able to distinguish 20 colors.
Color vision deficiency is usually hereditary, though it is sometimes caused by injury. Color vision is encoded on the X chromosome, which means that men are far more likely to have color vision deficiencies than women. About 8% of men and about 0.5% of women have a color vision deficiency. Some people truly are “color blind” in that they cannot see any colors at all. This is called “achromotopsia” and is very rare: it affects around 1 in 30,000 people. Achromotopsia is also associated with poor visual acuity and nystagmus.
What does it mean for my child to have color vision deficiency?
Unfortunately, children with color vision deficiencies will often have trouble at school. Many worksheets and exercises are color coded (“color the circle red” or “how many green dots are there?”), and later, charts and graphs used in assignments often have a color component. These can be very difficult and frustrating for children with color vision deficiency. That’s why, if you know that your child has color vision deficiency, it is important that you talk with his or her teachers so they all know about it and can adjust those accordingly.
Color deficiency is common enough that statistically, there will be one student with color vision deficiency in each classroom. However, you may still need to advocate for your child and make sure he or she receives the adaptations they need in school. There’s a nice post at ColorVisionTesting that talks about ways teachers can help their students with color vision deficiency.
Children normally develop full color vision by 6 months, but as most parents will tell you, they won’t know their colors by name until well past that age. At age 2, they should be starting to match colors, around age 3 beginning to name colors, and between 4 and 6, have good color naming skills. Parents of children with strong color vision deficiency often start to notice problems between the ages of 3 and 10. If you’re noticing that your child is consistently confusing colors or naming colors incorrectly, they should be tested before starting Kindergarten.
There are online color vision tests, but you will need to see an eye doctor to diagnose color vision deficiencies accurately.
