Macular degeneration is an eye disease that occurs when the
small central portion of the retina, known as the macula, is
damaged. The retina is the light-sensing nerve tissue at the back
of the eye. Because the disease develops as a person ages, it is
often referred to as age-related macular degeneration (AMD).
There are two types of age-related AMD, the "dry" form and the
"wet" form.
Dry form of AMD
The "dry" form of AMD is
characterized by the presence of yellow deposits, called drusen, in
the macula. In general, drusen does not cause changes in vision.
However, as they grow in size and increase in number, they might
lead to a dimming or distortion of vision that people find most
noticeable when they read. In more advanced stages of dry AMD,
there is also a thinning of the light-sensitive layer of cells in
the macula leading to atrophy, or tissue death. In the atrophic
form of dry AMD, patients might have blind spots in their vision.
In the advanced stages, patients might even lose central
vision.
Wet form of AMD
The "wet" form -- or exudative
neovascular form of AMD -- is characterized by the growth of
abnormal blood vessels from the choroid underneath the macula. This
is called choroidal neovascularization. These blood vessels leak
blood and fluid into the eye, causing distortion of vision that
makes straight lines look wavy, as well as blind spots and loss of
central vision. These abnormal blood vessels eventually scar,
leading to permanent loss of central vision.
Most patients with AMD have the dry form of the disease and will
not lose central vision. However, the dry form of AMD can lead to
the wet form. Although only about 10 percent of people with AMD
develop the wet form, they make up the majority of those who
experience serious vision loss from the disease.
Because the dry form can change into the wet form, it is very
important for people with AMD to monitor their eyesight carefully
and see their eye doctors on a regular basis.
Who gets AMD?
As the name suggests, AMD is more
common in older adults. In fact, it is the leading cause of severe
vision loss in adults over age 60.
AMD might be hereditary, meaning it can be passed on from
parents to children. If someone in your family has or had the
condition, you might be at higher risk for developing the disease.
Talk to your eye doctor about your individual risk.