Colour blindness is a condition where a person cannot figure out the difference between certain colours. This happens because he/she may be born without certain color sensitive pigments in their eyes. These pigments are usually present in the cones of the eye, which are present at the back of the eyeball.
The eye has a number of components, and one of the most important parts of the eye is the retina. The retina is placed at the back of the eyeball and is packed with nerve endings that carry impulses to the brain along with two types of photoreceptor cells, called the rods and cones.
The rods are mainly responsible for perceiving the presence of light and are placed on the outer edge of the retina. The centeral part is filled with cones. Cones have a number of pigments that help it perform its main function of helping us see colours. These pigments have a different wavelength which when activated helps us perceive a colour. The three main colours that these pigments are sensitive to are– green, blue and red.
In the case of colour-blind people, because of the deficiency of certain pigments, they are unable to see these colours. For example what we may see as red, they may see as light green or grey, depending on the type of colour blindness they are suffering from.