What is it the retina?
The retina is a light-sensitive tissue lining the back of the eye containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed. The retina is considered part of the central nervous system (CNS) and is actually brain tissue. It is composed of many layers, all of which have specific functions. It contains photoreceptor cells called rods and cones. Rods aid in night vision and seeing black and white hues, whereas cones aid in daytime vision and seeing colors. The retina also contains the macula which helps in central vision and the optic disc, an area where the optic fibers leave the eye and go to the brain.
How does it work?
The retina acts like the film in a camera. The image is processed to the retina where it is then transmitted to the brain via the optic nerve. The photoreceptor nerve cells of the retina change the light rays into electrical impulses and send them through the optic nerve to the brain where an image is perceived. The center ten percent of the retina is called the macula. This is responsible for your sharp central vision. The peripheral retina is responsible for the peripheral vision. As with the camera, if the “film” is bad in the eye (i.e. the retina), no matter how good the rest of the eye is, you will not get a good picture.