Age-Related Macular Degeneration (AMD)
Age-related macular degeneration is a common eye disease that slowly destroys sharp, central vision as you age. Central vision is needed for seeing objects clearly and for common daily tasks such as reading and driving. In some people, AMD advances so slowly that it has little effect on their vision. In others, the disease progresses faster and may lead to a loss of vision in one or both eyes. People over sixty are at greater risk than other age groups.
The exact cause of AMD is not known. In many cases, the small vessels of the eye can become narrowed and hardened due to atherosclerosis. When this happens, the back of the eye doesn’t get the blood supply it needs. This, in turn, causes it to waste away or degenerate.
How does AMD Damage Vision?
The retina is a paper-thin tissue that lines the back of the eye and sends visual signals to the brain. In the middle of the retina is a tiny area called the macula. The macula is made up of millions of light-sensing cells that help to produce central vision. Damage to these cells causes a decrease in central vision.
AMD Occurs in Two Forms
Dry AMD
Ninety percent of all people with AMD have this type. Scientists are still not sure what causes dry AMD. Studies suggest that an area of the retina becomes diseased, leading to the slow breakdown of the light-sensing cells in the macula and a slow loss of central vision.
Wet AMD
Although only 10 percent of all people with AMD have this type, it accounts for 90% of all blindness from the disease. As dry AMD worsens, new blood vessels may begin to grow and cause “wet” AMD. Because these new blood vessels tend to be very fragile, they will often leak blood and fluid under the macula. This causes rapid damage to the macula that can lead to the loss of central vision in a short period of time.
What Are the Symptoms?
Macular degeneration is painless. With the dry form, it develops slowly. With the wet form, symptoms can occur more rapidly. Symptoms for both forms are:
- Blurred or cloudy vision.
- Seeing a dark or blind spot at the center of vision.
- Distorted vision such as straight lines that look wavy.
- Trouble reading or doing other close-up work.
- Trouble doing any activity that requires sharp vision (e.g. driving).
- Complete loss of central vision. Peripheral or side vision is not affected.
The classic early symptom of wet AMD is that straight lines appear crooked. This results when fluid from the leaking blood vessels gathers and lifts the macula, distorting vision. A small blind spot may also appear in wet AMD; this results in loss of one’s central vision.
Treatment of AMD
A major national study called the AREDS study notedthat high doses of the antioxidant vitamins A, C, and E along with zinc slowed down the progress of macular degeneration. There are many popular vitamin pills for the eyes. Your eye doctor can suggest some.
Treatments for wet AMD now include laser, cold laser using Visudyne®, and injections into the eye. Your doctor will need to determine which treatments will work best for you.
Low vision aids are often helpful. The simplest and most popular aid is a hand held magnifier. The University of Wisconsin Ophthalmology Clinic provides a low vision service that will show you aids and advise you which may be helpful to you.
Phone Numbers
Please call the Ophthalmology Clinic at (608) 263-7171 if you have any questions or concerns, or wish to schedule a clinic visit.
The Spanish version of this Health Facts for You is #7271.
The information provided should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Any duplication or distribution of the information contained herein is strictly prohibited.
Last Updated: 10/31/2011
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