When 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.
Age-related macular degeneration (AMD) is the foremost cause of vision loss in the U.S., with millions of 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 driving as well as close work like reading and sewing.
AMD occurs in two forms:
Dry: Most common
Wet: Less common, but requires immediate medical attention to preserve central vision
You 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.
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 vision.
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.
In this article
WebMD Medical Reference from Healthwise
September 09, 2014
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