Macular Degeneration


Why is the Macula Important?

Unlike a photograph in which the entire picture is in focus, our eyes can only focus on the object at which we are looking directly. (Try reading the first word of this sentence while staring at the period at the end of the sentence).

The macula is responsible for our clear central vision. The remainder of the retina is used for side or peripheral vision. Damage to the macula causes blurring of our central vision which may make it difficult to read, drive, watch television, and recognize familiar faces

What is Age-Related Macular Degeneration?

Macular degeneration is the leading cause of poor vision in the United States. Each year, approximately 170,000 new cases of age-related macular degeneration (AMD) are discovered. Macular degeneration occurs whenever a previously normal macula begins to deteriorate. Juvenile macular degeneration begins at a young age and is quite rare. AMD is very common and occurs in older people, although getting older does not always result in visual problems.

As AMD progresses, the central vision begins to blur, but the peripheral vision remains normal. Please remember that macular degeneration does not cause total blindness. Even at its worst, AMD spares peripheral vision and allows patients to care for themselves. Macular degeneration often affects both eyes, although the second eye may not become involved for many years.
There are two main types of AMD, dry macular degeneration and wet macular degeneration.
Ninety percent of macular degeneration patients have the dry form. The cells in the macula slowly wear out. The loss of central vision is often mild. Some patients may have progressive deterioration, usually over a long period of time, resulting in severe loss of central vision. Only 10 percent of severe loss of central vision is due to dry AMD.

The more severe wet (exudative form) affects 10 percent of macular degeneration patients. In this type, fluid may collect or abnormal blood vessels may grow underneath the retina. They often cause severe damage to the vision from bleeding and scarring under the macula. The wet form accounts for 90 percent of the patients with severe loss of central vision.

DRY AMD

DRY AMD

WET AMD

WET AMD

What Causes Age-Related Macular Degeneration?

Aside from aging, no specific cause of macular degeneration has been identified. Heredity plays a role in many patients. The disorder is limited to the eye and is not associated with problems elsewhere in the body. Tumors and infections are not associated with macular degeneration. Extensive use of the eyes, reading or watching television does not cause macular degeneration or result in further damage. There is nothing a person can do that will accelerate or retard the progress of AMD.

How do I Know if I Have Macular Degeneration?

Most people with macular degeneration have either blurred or distorted vision in one or both eyes. Distorted or wavy vision is a very important symptom and should be reported promptly to your doctor. This is especially true when straight lines (doorways, telephone poles, etc.) appear wavy. Many people with visual loss in one eye may not realize they have a problem because the good eye takes over for both eyes.

You will be given a special Amsler grid test to be used at home to help you recognize early changes in your vision or identify new areas of distortion This grid test should be used on a daily basis. It is very important to check each eye separately.

NORMAL AMSLER

NORMAL AMSLER

 Metamorphopsia

Metamorphopsia

What Tests Can I Expect?

The doctor will examine your eyes on each visit. If necessary, he may order a fluorescein angiogram. In this test, a dye is injected into an arm vein, and pictures are taken of the macula as the dye circulates through the blood vessels. In some cases, another type of angiogram, called High Speed-ICG, is used to take a movie of the deepest layers of the eye using a different dye and a special infrared camera.

Because the vessels of the eye can be photographed directly, no X-rays are involved and the tests are safe for patients who are allergic to X-ray dyes. Patients allergic to Iodine should only have High Speed-ICG with special precautions. The angiogram provides a detailed picture of the retinal blood vessels and will detect any abnormal vessels that might be present. The doctor uses this information to determine whether treatment might be helpful. The dye is excreted in your urine for up to 24 hours following the injection. The whites of your eyes and your skin might turn slightly yellow for a day. Hospitalization is not required for this test, and you are free to go home when it is finished.

What Treatment is Available for Macular Degeneration?

Intravitreal Injections

The most common treatment available for macular degeneration is the injection of medications inside the eye. The majority of these drugs are a class of medicatins called VEGF Inhibitors, VEGF-I, or Anti-VEGF. ANTI-VEGF stands for Anti Vascular Endothelial Growth Factor. VEGF is thought to play a major role in the pathogenesis of wet macular degeneration. The use of these medications has revolutionized the treatment of wet macular degeneration in the past 10 years. Patients who went universally blind in the past are now able to preserve and in some cases improve their vision. There are newer medications under research that may further enable us to treat this devastating disease.

Conventional Laser Treatment

Conventional laser consists of a strong beam of light, which enables the physician to seal (cauterize) the abnormal blood vessels, which may grow in the wet form of macular degeneration. In very rare cases, before the laser procedure, an anesthetic injection may be used. The injection often causes the vision in the treated eye to be blurred for several hours. You will be in a sitting position for the treatment. The actual laser treatment, which is not painful, usually takes less than 5 minutes. You will be able to return home immediately and resume your normal activities within 24 hours. Unfortunately, only some types of wet AMD respond to conventional laser. Laser treatment does not cure macular degeneration, and it does not necessarily prevent abnormal blood vessels from returning in the future. It is important for you to continue to test your vision with the Amsler grid chart. If further changes are noted, they should be reported promptly to your doctor. If the abnormal blood vessels do return, it may be possible to treat them with laser again.

Newer Laser Technique

Abnormal new blood vessels may grow into the very center of the macula in some cases of macular degeneration. Such cases represent the worst type of macular degeneration, requiring many visits and extreme efforts from both the patients and the doctor to control the disease and limit vision loss. Abnormal vessels may grow in a variety of patterns. Depending on the pattern of leakage, one of the new laser treatment techniques may be appropriate for an individual case. If the vessels are very well defined, photodynamic therapy (PDT) may be a reasonable treatment recommendation. This involves injection of a medicine called Visudyne, which is selectively absorbed by abnormal, growing blood vessels. The medicine is allowed to adsorb for 15 minutes after beginning infusion through an intravenous line. Nonburning, red laser light is then shown into the eye, which activates the medicine. This chemically cauterizes the abnormal blood vessels, with relatively little effect on the surrounding normal tissue. This results in visual improvement in only about 15 to 20 percent of cases, but prevents further vision loss in another 50 to 60 percent. This is not the cure, but an effective way to prevent further vision loss in many patients. If vessels grow in the center of the macula, resulting in a diffuse pattern of fluid leakage, photodynamic therapy has been shown not to be helpful. In these cases, transpupillary thermal therapy (TTT), another new treatment technique may be useful. Instead of applying a hot laser, which burns the tissue that it touches, transpupillary thermal therapy involves gently heating this area with much cooler laser settings. This results in very mild photocoagulation of the abnormal tissue, with less damage to surrounding normal tissue. This has been shown to stabilize or improve vision in 50 to 70 percent of patients with this pattern of leakage. All of these treatments seek to treat the area of leakage directly. These leaky blood vessels grow in a pattern like a small flat tree or bush underneath the retina. In many cases, it would be just as effective to treat the underlying trunk blood vessel, which feeds this tree. In the past, available cameras have not been able to visualize the feeder vessel. There is a new kind of camera now available which can, in many cases, visualize this feeder vessel. Feeder Vessel Therapy (FVT) has been shown to be useful in some cases not treatable by other means.

Vitamins

Research suggests that certain dietary supplements may help. Vitamins and minerals such as zinc, vitamin E and selenium are advocated by some researchers for the purpose of trying to prevent further visual loss from dry macular degeneration. Other substances that have received much attention include Bilberry and Lutein. Current studies now show that antioxidant vitamins and zinc do seem to help, at least with more advanced disease. Taking one of the “eye vitamin” supplements as directed provides approximately what was recommended in the Age Related Eye Disease Study (AREDS). Your doctor will discuss them with you if he or she feels they might be appropriate for you.

Dietary Measures

In addition to the vitamins listed above, some people do believe that certain foods, which contain these vitamins, or other factors may help control the progression of macular degeneration. Such foods include dark green leafy vegetables, red wine (particularly the Cabernet and Petit Syrah grapes) and other foods rich in antioxidant vitamins.

Surgery

Very few patients with AMD will need surgery. Surgery may be considered when abnormal new vessels grow in the center of the macula or when a very large hemorrhage occurs. These are instances in which the eye is threatened with severe visual loss. Your doctor will discuss this further if it is appropriate.

What to Do if You Have Macular Degeneration?

Have a regular eye examination at least once yearly. If you are seeing a retinal specialist as well as your general eye doctor, you may be able to alternate visits to maximize convenience and reduce cost.

Use an Amsler grid at home to monitor your vision. Look at the chart from reading distance using any bifocals or reading glasses you normally use. All you have to do is take a quick glance. If you stare at it for too long, the image will fluctuate and become confusing.
Quit smoking and control your blood pressure as well as you can. Both of these measures may help.
At least consider using antioxidant vitamin supplements. There is some evidence that these may help stabilize the wear and tear process. There are three reasonable options:
Use a multivitamin such as Centrum Silver or an equivalent,
Use an “eye vitamin” such as Ocuvite or I-caps,
Go “ala carte” using single preparations including Vitamin A, D, E, C, B complex, zinc, and selenium. Other supplements that may help include Lutein, zeaxanthine, Billberry, and Ginko biloba.
The most convenient choice is to use an eye vitamin, which contains Lutein either with or without a multivitamin. It is also reasonable for your younger family members to consider using these, since the disease has a hereditary component, and the vitamins may have a preventative effect.
Eat well and consider including food types that are suggested to have beneficial effects. These would include dark, green leafy vegetables such as spinach, other sources of the vitamins listed above, and red wine (especially from the Cabernet and Syrah grapes).

Adapted from
http://www.sabateseye.com