Learn Basics about the Leading Cause of Blindness in the U.S.
By Guest column Connie Chen, MD
Stephen King, Georgia O’ Keefe, Sam Snead, Bob Hope and Edgar Degas all have something in common — loss of vision due to a condition called macular degeneration.
As many as 11 million Americans have some form of the disease and it is the leading cause of blindness in the United States.
The part of the eye affected is the macula, the area of the retina that is responsible for the sharp, central vision we need for reading and tasks that require seeing things in detail, such as sewing.
Although macular degeneration sometimes occurs in younger people, the condition mainly affects people 65 and older, so it is generally referred to as age-related macular degeneration or AMD.
Symptoms of AMD
The onset of AMD is so gradual that early in the course of the disease most patients don’t notice any loss of vision. As a result, early AMD often goes undiagnosed until the individual has an eye exam.
However, as the disease progresses, vision may become blurred and objects may appear distorted. Individuals with AMD may first notice they are missing letters in words when they read or have difficulty seeing smaller print.
In more severe cases, there may be a significant loss or graying of central vision, while peripheral vision remains unchanged. A person’s ability to adapt to different lighting environments may also be affected.
Causes of AMD
The loss of vision is associated with two major changes in the retina. First, there is a build up of cellular debris within the retina, which produces yellow deposits called “drusen.” Second, in some cases the retina releases chemicals that stimulate the growth of new blood vessels, a process called “neovascularizaiton.” The new blood vessels, however, are weak and often leak blood and fluid that damages the surrounding retinal tissue.