Inherent Colour blindness is a usually a genetic (hereditary) condition (you are born with it). Red/green and blue colour blindness is usually passed down from your parents. The gene which is responsible for the condition is carried on the X chromosome and this is the reason why many more men are affected than women.
Chronic illnesses-Although some people become colour blind as a result of long-standing diseases such as diabetes, multiple sclerosis, some liver diseases and almost all eye diseases.
Accidents or strokes that damage the retina or affect particular areas ofthe brain/eye can lead to colour blindness.
Medications such as antibiotics, barbiturates, anti-tuberculosis drugs, highblood pressure medications and several medications to treat nervous disordersmay cause colour blindness.
Industrial or environmental chemicals such as carbon monoxide, carbondisulphide and some containing lead can also cause colour blindness.
Age – in people over 60years of age physical changes can occur which might affect a person’s capacityto see colours
The exact physical causes of colour blindness are still being researched but it is believed that colour blindness is usually caused by faulty cones but sometimes by a fault in the pathway from the cone to the brain.People with normal colour vision have all three types of cone/pathway working correctly but colour blindness occurs when one or more of the cone types are faulty. For example, if the red cone is faulty you won’t be able to see colours containing red clearly.Most people with colour blindness can’t distinguish certain shades of red and green.see below normal colour v/s colour blindness