What causes colour blindness?

We know that seeing colour is a result of our red, green and blue cone cells sending signals to our brain. What happens when there is a problem with these cone cells? Colour blindness is the result of a defect in one or more types of cone cells. Colour blindness is a condition in which the eyes have difficulty distinguishing certain colours. Someone who has green colour blindness has a defect with their green cone cells (same with blue and red). Blue colour blindness and monochromatism (only able to see black, grey, and white) are very rare. Green colour blindness is called deutranopia, red colour blindness is called protanopia and blue coulour blindness is called tritanopia. Colour blindness is usually a genetic disorder but can also be caused by damage to the retina or the optic nerve (the nerve that takes information from the eye to the brain).