The human eye functions similarly to a camera. Light enters through the cornea, passes through the pupil (regulated by the iris), and is focused by the lens onto the retina. The retina is the light-sensitive tissue lining the back of the eye; it contains photoreceptor cells (rods and cones) that convert light into electrical signals. These signals are then transmitted to the brain via the optic nerve, where they are interpreted as an image. Therefore, the image of an object is formed on the retina.