age-related macular degeneration (dry AMD), the cells and blood vessels beneath the macula begin to thin and break down as they age.
these cells and blood vessels stop working, the nerve cells in the macula that
detect light can't work as well as they used to. As more and more of the nerve cells in
the macula break down, vision loss very slowly gets worse.
Macular degeneration is the leading cause of severe vision loss in people over age 60. It occurs when the small central portion of the retina, known as the macula, deteriorates. 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). Although macular degeneration is almost never a totally blinding condition, it can be a source of significant visual disability.
may have the disease for several years before it affects how you are able to read,
drive, and do everyday activities. If you have AMD in only one eye, you may not
notice minor vision changes, because your unaffected eye automatically makes up
for vision problems in your other eye.
A small percentage of people who have dry AMD eventually develop
Wet AMD begins with the growth of abnormal blood vessels under the macula. These blood vessels break easily. They
leak blood and fluid and cause scar tissue, all of which push against the
macula. They change the macula's shape and cause it to send distorted images to
your brain. Straight lines begin to appear wavy or curved, and objects may seem
oddly shaped or smaller.
Scar tissue also cuts off the macula
from the normal support cells that it needs in order to work. Nerve cells in
the macula begin to die, causing a loss of central vision.
If not treated, the scar beneath the macula may continue
to grow, affecting more and more of the nerve cells in the macula. Vision loss
gets worse as more of the macula becomes involved. The entire macula may be
destroyed by this process, resulting in a complete loss of central
Treatment can sometimes delay or prevent further vision
loss, but it cannot reverse vision loss that has already occurred.
With wet AMD,
vision loss can happen fast—within months or even weeks. This can make it hard to adjust to
the vision loss.
Even though AMD may affect
central vision, it doesn't cause complete blindness. And most people keep good side vision.
WebMD Medical Reference from Healthwise
November 12, 2012
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