Vision begins when light rays are reflected off of an object and enters the eye through the cornea and then pupil. It is then passes through the crystalline lens which refracts light to be focused on the retina. By changing shape, the lens functions to change the focal distance of the eye so it can focus on objects at various distances.
The retina is a light-sensitive layer of tissue, lining the inner surface of the eye. It captures light sent through the cornea and crystalline lens to create an image by triggering nerve impulses that pass to various visual centers of the brain via the optic nerve.
When light hits the retina, tiny cells, rods and cones, capture the light signals and convert them into electro-chemical impulses in neurons. Rods communicate the object’s shape by reading black, white, and shades of grey. Cones communicate the color of the object.
Working together, the rods and cones process the light to create an image by triggering nerve impulses that pass to various visual centers of the brain via the optic nerve.