Macular Degeneration

What is macular degeneration?

Macular degeneration is a lesion or breakdown of the macula. The macula is a small area of the retina at the back of the eye that allows you to see fine details clearly and perform activities such as reading or driving a car. When the macula does not function properly, your central vision may be affected by the formation of blurred images, with dark or distorted areas. Macular degeneration affects your ability to see near and far objects. It can make some activities (such as threading a needle or reading) difficult or impossible.  

Although macular degeneration reduces the vision of the central part of the retina, it does not affect the lateral or peripheral vision of the eye. For example, you can see the outline of the clock, but you cannot tell what time it is.  

Macular degeneration alone does not lead to total blindness. Even in the most advanced cases, people continue to have some useful vision and are often able to care for themselves. In many cases, the impact of macular degeneration on vision may 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 AMD. The precise cause of its development is unknown. No treatment has been consistently effective. Macular degeneration is the leading cause of severe vision loss in people over 65 years of age.  

The two types of AMD are:

• Dry (atrophic).

• Moist (exudative).

Dry” macular degeneration (atrophic)

Most people present with the “dry” form of AMD. It is caused by advancing age and thinning of the macular tissues. Usually, vision loss is gradual.

Wet” macular degeneration (exudative)

The “wet” form of AMD covers approximately 10% of all cases. It occurs when abnormal blood vessels form under the retina at the back of the eye. These new blood vessels allow leakage of fluid or blood and produce blurred central vision. Vision loss can be rapid and severe.

What are the symptoms of macular degeneration?

Macular degeneration can cause different symptoms in different people. This condition may be practically imperceptible 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 can be perceived more quickly.  

Listed below are several ways in which vision loss is detected:

• Words written on a page appear blurred.

• A dark or empty area appears in the center of vision.

• Straight lines appear deformed.

How is the diagnosis of AMD made?

Many people do not notice the macular condition until the blurred vision becomes obvious. Your ophthalmologist (eye doctor) can detect AMD in its early stages during an eye exam that includes the following:

• A simple vision test in which you look at a graph that looks like graph paper (Amsler grid).

• Observing the macula with an ophthalmoscope.

• By means of an OCT retinal scanner, which gives us images of anatomical slices of the macula.

• Sometimes special fluorescein photographs of the eye called angiograms are taken to find abnormal blood vessels behind the retina. Fluorescein is injected into a vein in the arm and then the eye is photographed as the dye passes through the blood vessels in the back of the eye.

Deposits that concentrate under the retina, called drusen, are a common cause of AMD. These deposits do not cause vision loss by themselves, but their increased number may be an indication of risk for developing advanced AMD. People at risk of developing advanced AMD have a significant amount of “drusen”, prominent dry AMD or abnormal blood vessels behind the macula in one eye (wet AMD).

How is AMD treated?

Nutritional supplements:

Although the precise causes of AMD are not completely known, the use of antioxidant vitamins and zinc may reduce the impact of AMD in some people.

An extensive scientific study has determined that people at risk of developing advanced stages of AMD can reduce their risk by 25% through a treatment that combines vitamin C, vitamin E, beta carotene and zinc.

These nutritional supplements do not appear to provide benefits among people without AMD, or in the early stages of AMD development.

It is very important to remember that vitamin supplements are not a cure for AMD, nor will they restore vision that has already been lost due to the disease. However, specific amounts of these supplements play an important role in helping to maintain vision among people at high risk of developing advanced AMD. You should talk to your ophthalmologist to determine if you are at risk of developing advanced AMD, and to find out if vitamin supplements are recommended.

Laser surgery and photodynamic therapy:

Certain types of “wet” AMD can be treated by laser surgery, a brief, outpatient procedure. Laser surgery and another form of treatment, called photodynamic therapy, uses a focused beam of light to slow, or stop, the outflow of fluid from blood vessels that damage the macula. These procedures may help preserve more vision, but they are not cures that can restore normal vision.

Intravitreal injections of antiangiogenic agents:

It is the current treatment par excellence. Despite advances in medical treatment, many people with AMD still experience some vision loss. To help you adapt to lower vision levels, your ophthalmologist may prescribe optical devices, refer you to a specialist or to a center for patients with reduced vision. A wide range of support services and rehabilitation programs are also available to help people with AMD maintain a fulfilling lifestyle.

Because lateral vision is usually unaffected, the patient’s remaining vision is very useful. Often, people continue to perform many of their favorite activities through the use of optical devices such as magnifiers, closed circuit television, large print reading materials, and computerized speech devices.