The retina is the film of the eye. It is present in the back of the eyeball and is at a distance of almost 17-18mm from the back of the lens. The retina is made of sensitive cells known as photoreceptors. The nerve fibers of these photoreceptors pass through the optic nerve and take vision to the brain. Depending upon the position of cell bodies and nerve fibers, 10 different layers of retina can be distinguished!!
There are 2 types of photoreceptors, cones & rods. The cones are highly sensitive and are responsible for fine vision like the color of objects, intricate details, reading vision, etc. Cones are mainly present in the central portion of the retina known as Macula. The Center of the macula is a very tiny area, known as the fovea. The fovea is almost as small as a pinhead. But it is responsible for fine vision almost entirely. Rods are more sensitive in dim light conditions and help one see in low contrast conditions like dusk time. However rods are unable to distinguish fine details. They are more in numbers in Peripheral retina.