Macular Degeneration is the name for several similar conditions that are characterised by a breakdown of the macula. The word "macula" comes from the Latin for "spot"; it is the centre portion of the retina that makes central vision, the vision directly in front of.you, possible. The macula is very small: only about three by five millimetres (about the size of a ladybug) covering about 10 percent of the retina.

To understand what Macular Degeneration can mean for your vision, it is helpful to understand a little bit about how the eye works. The eye operates like a complex machine, requiring a number of intricate, interrelated parts to act together. If one part is damaged or impaired, it will affect the others. The retina is the delicate innermost layer of tissue that lines the eyeball. It contains various layers of light-receiving - or photo receptor - cells that are directly connected to the brain by the optic nerve. The entire retina contributes to sight. If you think of the eye as a camera receiving images, then the retina is the film where those images are recorded.

There are two types of photo receptor cells in the retina: cone cells and rod cells. The cone and rod cells convert light into electrical impulses that travel through several types of nerve cells and converge in the optic nerve, which is the "cable" that carries the final electrical transmission from the eye to the brain, where "seeing" actually occurs. The rod cells are concentrated outside the macula and are required for peripheral and night vision. The cone cells are concentrated in the macula and are responsible for central and colour vision. The macula is also responsible for visual acuity, which is the ability to see things clearly and discriminate the fine details of objects.