Colour blindness is usually a genetic (hereditary) condition (you are born with it). Red/green and blue/yellow colour blindness types are usually passed down from your parents. The gene which is responsible for red/green colour blindness is carried on the X chromosome and this is the reason why many more men are affected than women. The inheritance process is explained in more detail at Inherited Colour Vision Deficiency
Inherited blue/yellow colour blindness is very rare because it is inherited differently to red/green types. The majority of our website concentrates on red/green types but we definitely do support people with blue/yellow (tritan) deficiencies! If you are affected, rest assured that all of the advice we provide will support people with all forms of CVD!
8% of the male population and 4.5% of the population of the UK as a whole have a form of red/green colour blindness. There are estimated to be over 300 million colour blind people worldwide. The vast majority of people with a colour vision deficiency have inherited their condition from their mother, who is normally a ‘carrier’ but not colour blind herself. Some people also acquire the condition as a result of long-standing illness such as diabetes, multiple sclerosis, some liver diseases and many eye diseases. Read more about acquired conditions.
The effects of colour vision deficiency can be mild, moderate or severe depending upon the defect. If you have inherited colour blindness your condition will stay the same throughout your life – it won’t get any better or worse.