Colour vision deficiency

The term 'colour blindness' is misleading. People who can't see all colours can still see things (other than colour) as clearly as people who are not colour blind. The term means that a person can't see some colours, or sees them differently from other people. Very few people who are colour blind are blind to all colours. The usual colours that people have difficulty with are greens, yellows, oranges and reds. Colour blindness is inherited, affecting more boys than girls. Out of 20 boys, it is likely that one or two will have a colour vision problem.