The macula, located in the center of the retina, is where most of the cone cells are located. It is very small (500µ or about the size of a ballpoint). The fovea, a small depression in the center of the macula, has the highest concentration of cone cells. The macula is responsible for central vision, seeing color, and distinguishing fine detail. The outer portion (peripheral retina) is the primary location of rod cells and allows for night vision and seeing movement and objects to the side (i.e., peripheral vision). All signals from the photoreceptor cells pass through the optic nerve head, which in turn, transmit them to the brain. Once they reach the brain, they are corrected and combined into one image. This complex process of analyzing data transmitted through the optic nerve is called visual processing.