Colour Blindness
Colour blindness (or Colour Vision Deficiency) is about more than just seeing in black and white.
What’s in it
What is it for?
Colour blindness (or Colour Vision Deficiency) is about more than just seeing in black and white. It affects roughly 1 in 12 men and 1 in 200 women. It changes how people perceive the world, which is a huge issue if colour is the only way information is conveyed. For example, a 'red for error' and 'green for success' status light might look the same to someone with red-green colour blindness.
How to support it
Design content to accommodate the various ways that people see. Here are the main types:
- Red-Green is the most common, and it has two main types:
- Protanopia - Red light looks dark. Crucially, purple often looks just like blue to these users.
- Deuteranopia - Green light is hard to detect. This means red and green can look almost identical (often a muddy yellow-brown).
- Blue-Yellow (Tritanopia) is much rarer. It makes it hard to distinguish between blue and green, or yellow and red.
- Monochromacy is very rare. This is seeing no colour at all, only shades of grey.
To make your work accessible, never rely on colour alone. Always add a text label, an icon, or a pattern (like hatching on a chart) so the information is clear regardless of the colour.