A degenerative disease that affects the central spot (macula) of the retina, which is responsible for central vision. Age-related macular degeneration is the most common cause of vision loss in people over 60. There are two types: wet and dry. Some people with wet macular degeneration may be helped by laser surgery. The cause of this disease is unknown, but scientists are studying whether vitamin and mineral supplements can prevent or slow its development.
A spot of eye trouble
Macula is a Latin word that means spot. In macular degeneration, a pea-sized spot in the center of the retina is permanently damaged. This spot is responsible for central vision.
When the macula is injured, objects directly ahead look blurry. Details are lost. There is a fuzzy "hole" in your vision. When looking at a face, only the ears are clear. People see a picture frame clearly, but not the picture.
How badly central vision is blurred depends on the amount of damage. Macular degeneration develops slowly and painlessly over time. It may affect one or both eyes.
People with macular degeneration have difficulty:
reading small print, street signs and distant faces or objects
driving, sewing and doing close work
Side vision remains normal, so people with macular degeneration can walk and perform daily activities without help. Two kinds of macular degeneration (MD) can affect central vision:
Dry MD
About 90% of people have dry MD. Behind the retina, a membrane separates the central spot or macula from its blood supply. Over the years, this membrane ages, thins and breaks down – exposing light-sensitive cells in the central spot to leaky or abnormal blood vessels. Cut-off from their food supply, these cells eventually stop working.
There is no way to reverse this damage. Central-vision loss occurs slowly and is usually mild. Someone with dry MD in one eye may not notice any difference in their vision.
Wet MD
Only 10% of people have wet MD, but it accounts for 90% of MD-related vision loss. It occurs when fragile blood vessels, growing between the macula and supporting layer of tissue, leak or rupture. Leaking blood or fluid damages light-sensitive cells in this region, leading to a rapid loss of central vision over a short time.
One early warning sign is visual distortion: straight lines look wavy. This happens when blood-vessel leakage forms bumps under the macula. Or, a blind spot may appear. Prompt laser therapy can prevent or slow central-vision loss.
No one knows exactly what causes macular degeneration (MD), but it tends to affect:
more women than men
smokers
and
people with high cholesterol
a family history of MD
extreme nearsightedness (myopia)
light-colored eyes
A lack of certain vitamins and minerals may play a role. The National Eye Institute (USA) is sponsoring the Age-related Eye Disease Study to find out if vitamin and mineral supplements can delay or stop macular degeneration.
MD is uncommon in Black and Asian people. There is no proof that, over time, exposure to the sun’s ultraviolet rays causes MD.
Two types of macular degeneration (MD) mean two different therapies.
Dry MD
Nothing can fix the slow breakdown of light-sensitive cells in the retina’s central spot or macula, but people with dry MD rarely have a total loss of vision. They can still use peripheral or side vision to see details. High-intensity reading lamps, magnifiers and low vision aids can help people with macular degeneration enjoy a normal, independent lifestyle.
What causes MD is unknown, but some people believe that antioxidants, such as vitamins C and E, and zinc supplements may help slow central-vision loss. Scientists are now studying how vitamins and minerals affect MD. Talk with an eye doctor before taking any natural remedies.
Wet MD
The eye doctor may ask you to use an Amsler grid to check your vision daily at home. If straight lines on the checkerboard pattern look wavy, see the eye doctor without delay.
In some people, laser surgery can seal leaky blood vessels in the early stages of wet MD. If the eye doctor sends you to an eye surgeon, don’t delay! Prompt treatment of new blood vessels, growing under the retina’s central spot or macula, may prevent damage to light-sensitive cells – and stop further loss of sight.
To find out if laser surgery can help, the eye doctor may suggest fluorescein angiography. This test detects leaky and abnormal blood vessels in the eye. Fluorescein angiography is usually done in a hospital by an eye specialist (ophthalmologist). Before the test, a yellow or red dye is injected into an arm vein. During the injection, the arm may feel slightly warm.
The fluorescein dye travels rapidly through the body’s circulation. When exposed to ultraviolet rays during the test, the dye glows yellow-green. The eye specialist photographs the fluorescent dye as it travels through blood vessels in the eye. Any leaks or abnormalities show up on the series of photographs.
Laser surgery for wet macular degeneration
At the eye-care clinic, the eye doctor dilates the pupil, then numbs the eye with drops. In the dimly lit room, a high-energy laser beam is directed through a special lens into the back of the eye. This operation, known as photocoagulation, takes only a few seconds. People often see light-green or red flashes of light, depending on the type of laser used.
The laser beam destroys fragile blood vessels behind the retina’s central spot (macula). Photocoagulation seals any blood or fluid leaks. By controlling bleeding and preventing the spread of abnormal vessels, photocoagulation protects the macula.
After surgery, blurry vision is common for about a day. The eye doctor usually prescribes drugs for pain. Frequent check-ups are the only way to find out whether new leaks have developed.
Vitamin and mineral supplements cannot restore lost vision or reverse the effects of macular degeneration (MD). But some eye doctors believe that antioxidant vitamins and mineral supplements may stop MD from getting any worse.
As yet, there is no certain link between dietary supplements and MD. Their role is controversial. The National Eye Institute (USA) is now studying how they affect the eye.
Antioxidants
People who eat leafy green vegetables, such as spinach, may develop MD less often. These foods are high in antioxidants, such as beta carotene and vitamins C and E, and the mineral selenium.
Zinc
Zinc supplements may slow MD. High concentrations of zinc occur naturally in the eye, and this trace mineral is important for a healthy retina. Elderly people often have low zinc levels – due to poor diet or less ability to absorb zinc from food – so some eye doctors recommend zinc supplements.
Not all eye doctors agree about the value of these supplements. Too much zinc can upset the action of other trace minerals, such as copper.
Before buying dietary supplements, consult an eye doctor to find out how much and what to take.
Age-related macular degeneration (AMD) is the most common cause of severe vision loss in the United States and Great Britain. It occurs in 1% of people under age 55, 10% of people between 65 and 75, and in 30% or more after 75. By age 90, everyone has signs of AMD.
Juvenile macular degeneration – a group of inherited macular disorders that occur in youth – is uncommon.
Sources
http://www.eyesearch.com/macular.degeneration.htm
http://www.aoanet.org
http://www.aao.org
