Colour blindness is an eye condition that changes the way people see colours. It doesn’t seem like a big thing to people who have normal colour vision. But when it comes to reading things like maps, it matters a lot. Graphs, maps, diagrams and other graphic information types often rely on colour to differentiate between elements and features.
With genetic colour blindness, men are about 16 times more likely to be affected than women. Injury or disease can also affect the ability to see certain colours.
Apart from genetic reasons, some health conditions increase the risk of developing colour blindness later in life. Macular degeneration, glaucoma, diabetes, dementia, and Parkinson’s disease can all affect colour vision. Because it happens later in life it often gets unnoticed and undiagnosed. Some medications might affect colour vision too. For more, see My Vision guides.
You are at greater risk of colour blindness if you are a white male and have family members with colour blindness.
Red-green colour vision deficiency occurs in 1 in 12 males with Northern European ancestry. For women it’s 1 in 200.
The Axess Lab website has some great tips for making graphics more inclusive. For example, putting text into pie charts, and labelling goods with colours not just showing them. Colour contrast matters too as you can see in the picture below.
Readability and colour choice
Colour choice is also a factor in readability. The video below shows how easily we can be deceived by our eyes. It shows how two different shades of grey are actually the same. That’s why you can’t rely on judging contrast by eye.