Explanation:

Colour blindness (achromatopsia) is caused due to the fault in the retina.
Most colour blind people are able to see things as clearly as other people but they are unable to fully 'see' red, green or blue light. There are different types of colour blindness and there are extremely rare cases where people are unable to see any colour at all.
Colour blindness usually involves the inability to distinguish between shades of red and green.
There is no treatment for inherited colour blindness. If colour blindness is caused by another condition, treating the underlying cause can help.