Understanding Macular Degeneration - the Basics

What Is Macular Degeneration?

Age-Related Macular Degeneration (AMD) is the number 1 cause of vision loss in the U.S., with more than 13 million Americans showing some sign of the disorder. AMD is uncommon in people younger than 55.  If you are over 65, macular degeneration may already affect your central vision -- the vision you need for close work like reading and sewing. 

AMD occurs in two forms:

• Dry: Most common
• Wet:  Less-common but requires immediate medical attention to prevent loss of central vision

Most people with AMD do not become totally blind.  Moreover, regular examinations can detect progression of AMD so that preventive treatment can be offered.  Recent innovations in AMD can halt or slow progression of retinal changes.

What Causes Macular Degeneration?

In order to understand macular degeneration let's get to know the macula. The word comes from a Latin word meaning “spot.”  The macula is a very small portion of the retina about the size of a pencil eraser.  The macula is loaded with photoreceptors, that enable you to read, watch television, drive, sew -- anything that requires focused, precise vision.

Outside of the macula there are far fewer photoreceptors, so image resolution is much poorer.  Although this part of the retina can continue to process images along the edge your field of vision, the tissue damage caused by AMD distorts or obscures part of the crisp central image that your eye transmits to your brain.

In the dry form of AMD, tiny yellow deposits develop beneath the macula, signaling a degeneration and thinning of nerve tissue. 

A small number of cases develop into the wet, or neovascular, form of AMD, in which abnormal blood vessels grow beneath the macula.  As these vessels leak blood and fluid onto and underneath the retina, retinal cells die -- causing blurs and blank spots in your field of vision.