In the again of the Eye, the optic nerve and certain blood vessels pierce the sclera. Cone cells are the second type of light delicate cells within the retina of the eye. The human retina accommodates between six and seven million cones; they operate finest in shiny light and are essential for acute vision . It is believed that there are three types of cones, every delicate to the wavelength of a special major color – pink, green or blue. Other colours are seen as combinations of those main colours.