What is macular degeneration?
Macular degeneration is a deterioration or breakdown of the macula. The macula is a small area in the retina at the back of the eye that allows you to see fine details clearly and perform activities such as reading and driving.
When the macula does not function correctly, your central vision can be affected by blurriness, dark areas or distortion. Macular degeneration affects your ability to see near and far, and can make some activities-like threading a needle or reading-difficult or impossible.
Although macular degeneration reduces vision in the central part of the retina, it does not affect the eye’s side, or peripheral, vision. For example, you could see the outline of a clock but not be able to tell what time it is.
Macular degeneration alone does not result in total blindness. Even in more advanced cases, people continue to have some useful vision and are often able to take care of themselves. In many cases, macular degeneration’s impact on your vision can be minimal.
What causes macular degeneration?
Many older people develop macular degeneration as part of the body’s natural aging process. There are different kinds of macular problems, but the most common is age-related macular degeneration (ARMD). Exactly why it develops is not known, and no treatment has been uniformly effective. Macular degeneration is the leading cause of severe vision loss in Caucasians over 65.
The two most common types of ARMD are “dry” (atrophic) and “wet” (exudative):
“‘Dry” macular degeneration (atrophic)
Most people have the “dry” form of AMD. It is caused by aging and thinning of the tissues of the macula. Vision loss is usually gradual.
“Wet” macular degeneration (exudative)
The “wet” form of macular degeneration accounts for about 10% of all AMD cases. It results when abnormal blood vessels form underneath the retina at the back of the eye. These new blood vessels leak fluid or blood and blur central vision. Vision loss may be rapid and severe.
What are the symptoms of macular degeneration?
Macular degeneration can cause different symptoms in different people. The condition may be hardly noticeable in its early stages. Sometimes only one eye loses vision while the other eye continues to see well for many years.
But when both eyes are affected, the loss of central vision may be noticed more quickly. Following are some common ways vision loss is detected:
* words on a page look blurred;
* dark or empty area appears in the center of vision;
* straight lines look distorted as in the following diagram:
How is macular degeneration diagnosed?
Many people do not realize that they have a macular problem until blurred vision becomes obvious. Your ophthalmologist (Eye M.D.) can detect early stages of AMD during a medical eye examination that includes the following:
* a simple vision test in which you look at a chart that resembles graph paper (Amsler grid);
* viewing the macula with an ophthalmoscope;
* taking special photographs of the eye called fluorescein angiographs to find abnormal blood vessels under the retina.
* taking images of the eye called OCT. OCT images are very useful in determining the amount and extent of retinal swelling or edema.
How is macular degeneration treated?
Although the exact causes of macular degeneration are not fully understood, antioxidant vitamins and zinc may reduce the impact of ARMD in some people.
Large scientific studies have found that people at risk for developing advanced stages of ARMD lowered their risk by about 25% when treated with a high-dose combination of vitamins in the AREDS and AREDS 2 formulas. Among those who have no ARMD, the supplements did not appear to provide a benefit.
Deposits under the retina called drusen are a common feature of macular degeneration. Drusen alone usually do not cause vision loss, but when they increase in size or number, this generally indicates an increased risk of developing advanced ARMD. People at risk for developing advanced ARMD have significant drusen, prominent “dry” ARMD, or abnormal blood vessels under the macula in one eye (“wet” form).
It is very important to remember that vitamin supplements are not a cure for ARMD, nor will they restore vision that you may have already lost from the disease. However, specific amounts of these supplements do play a key role in helping some people at high risk for advanced ARMD to maintain their vision. You should speak with your ophthalmologist to determine if you are at risk for developing advanced AMD, and to learn if supplements are recommended for you.
Injections of anti-vegf and other medications into the vitreous cavity of the eye has been found to be very helpful in decreasing swelling from fluid leakage as well as causing abnormal blood vessels under the macula. This form of treatment has become the mainstay of wet ARMD treatment. Multiple injections over time, sometimes years are required to decrease and keep the swelling and abnormal blood vessels under control. The injections help stabilize and in some cases can even improve the vision.
Laser surgery and photodynamic therapy
Certain types of ” wet ” macular degeneration can be treated with laser surgery, a brief outpatient procedure. Laser surgery and another form of treatment called photodynamic therapy use a focused beam of light to slow or stop leaking blood vessels that damage the macula. These procedures may preserve more sight overall, though they are not cures that restore vision to normal.
Despite advanced medical treatment, many people with macular degeneration still experience vision loss.
To help you adapt to lower vision levels, your ophthalmologist can prescribe optical devices or refer you to a low-vision specialist or center. A wide range of support services and rehabilitation programs are also available to help people with macular degeneration maintain a satisfying lifestyle.
Because side vision is usually not affected, a person’s remaining sight is very useful. Often, people can continue with many of their favorite activities by using low-vision optical devices such as magnifying devices, closed-circuit television, large-print reading materials, and talking or computerized devices.
Testing your vision with the Amster grid
You can check your vision daily by using an Amster grid like the one pictured below. You may find changes in your vision that you wouldn’t notice otherwise. Putting the grid on the front of your refrigerator is a good way to remember to look at it each day.
To use the grid:
1. Wear your reading glasses and hold this grid at 12-15 inches away from your face in good light.
2. Cover one eye.
3. Look directly at the center dot with the uncovered eye.
4. While looking directly at the center dot, note whether all lines of the grid are straight or if any areas are distorted, blurred or dark.
5. Repeat this procedure with the other eye.
6. If any area of the grid looks wavy, blurred or dark, contact your ophthalmologist immediately.