Most of the sensory cells are present at this spot. It is another name for the macula. It is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea and perifovea areas. It has a diameter of 5.5mm in humans. They contain the pigment Iodopsin and respond to bright light and colour, because of which we can see stuff clearly around us. It lies at the back of the eye almost center of the horizontal axis of the eye ball.