Age-related Macular Degeneration (AMD)

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Age-Related Macular Degeneration

Age-related Macular Degeneration (AMD), the leading cause of legal blindness in people 65 years or older in the United States, affects more than 10 million Americans according to Prevent Blindness America. People with AMD may have difficulty with daily tasks that require fine vision such as reading, driving, recognizing faces, and dialing a telephone. However, AMD does not typically damage the side vision, which is what one uses to get around without bumping into furniture or other objects.

What is Macular Degeneration?

The retina is a layer within the eye made up of nerve cells that perceive light which is then transmitted to the brain so that we have vision. Thus, the retina acts very much like the film in a camera. Vision is distorted or decreased with significant AMD.

The retina has blood vessels that run within it just like the pattern in a wallpaper, but it also depends on support for proper nourishment from an underlying layer of blood vessels called the choroid. In between the choroid and the retina is a barrier filter called Bruch’s membrane that prevents unwanted fluid from accumulating under the retina. Although we talk of the macula as the central part of the retina the critical area within the macula is called the fovea. This is only 1/15 of an inch in diameter, about the size of a pinhead. Thus, our central vision which allows us to read and see fine detail depends on the health of this small, but very highly specialized area.

What Causes Macular Degeneration?

While we do not understand completely how the changes occur, dry macular degeneration is due to atrophy (wasting away of retinal tissue). In the wet form vision loss is usually caused by the growth of abnormal blood vessels that leak fluid and blood under the foveal area of the macula. The dry type of macular degeneration affects 90% of patients and the wet type the remaining 10%. Most macular degenerations start out as the dry type. The rate of visual loss in the dry stage is highly variable and many people maintain reading vision and good distance vision for years. At any time in the course of the disease, however, the condition can convert to the wet type and, at that point, significant visual symptoms usually suddenly occur.

In the wet type of AMD abnormal blood vessels from the choroid grow through cracks in the barrier filter (Bruch’s membrane) like grass through cracks in the sidewalk. They then leak fluid or blood and it is this leakage that initially distorts or decreases the vision. Ultimately, a large scar may form secondary to the leakage and bleeding which has occurred under the retina.

Although there is no way to halt or reverse damage from dry age-related macular degeneration, certain lifestyle and dietary measures can be taken that can help to decrease the risk of disease progression to the more advanced stages.

If you smoke cigarettes, you should try to stop. Smoking increases your risk of disease progression. Studies also suggest that a diet rich in leafy green vegetables may be beneficial. (If you are taking certain types of blood thinners, ask your medical doctor first before making significant dietary changes since they could negate to some degree the affect of some blood thinners.)

Lastly, published results from the Age-Related Eye Disease Study (AREDS) showed that a certain formulation of anti-oxidant vitamins and minerals can reduce the risk of dry age-related macular degeneration progressing to more advanced stages and associated vision loss. The daily dose of vitamins used in the study is listed here:

Please check with your doctor before starting this vitamin/mineral combination. In general, Vitamin E supplementation should not exceed 400 I.U. and smokers should not be on any beta carotene supplementation.

Risk Factors for AMD include:

• Family history of AMD (parents, brothers and sisters with the disease). Patients with a family history may show large drusen (yellow spots under the retina).
• Smoking
• High blood pressure and high cholesterol levels
• Obesity

8 Things You Can Do to Help Preserve Your Vision

1. Do not smoke.
2. Focus on healthy eating with a diet rich in green leafy vegetables, fruits, and fish once or twice a week. * See number 8
3. Cook with virgin olive oil, and avoid trans fats found in processed baked goods.
4. Maintain normal blood pressure and cholesterol levels.
5. Watch your weight.
6. Exercise
7. If you have been diagnosed with intermediate level dry AMD or advanced dry AMD in one eye, take the vitamin and mineral combination of vitamin C, vitamin E, beta-carotene and zinc, as stated earlier, in the form of Ocuvite or ICAPS after checking with your personal physician (once again smokers should not take beta-carotene).
8. Screening of those with a family history of AMD and those who smoke should be encouraged so that if large drusen are noted, the appropriate nutritional supplements mentioned earlier can be recommended. Because macular degeneration is more common as one gets older we encourage those in the Medicare population to be screened as well.

Laser photocoagulation

Photodynamic therapy (PDT) with verteporfin (Visudyne)

Anti-Blood Vessel Medical Therapy

FAQ's

There is no surgery that will help the dry type of macular degeneration. Recent scientific trials regarding surgical therapy for wet AMD concluded that it was generally of no value, although it may remain worthwhile in carefully-selected patients.

If a patient develops the wet form of macular degeneration in one eye there is a 10% chance over the next year that it may also happen in the fellow eye. If a second eye becomes affected with wet macular degeneration, the patient may understandably become depressed. It is important to point out that depression is treatable and that patients with macular degeneration can learn how to manage their lives quite successfully. In this regard low vision therapy can be helpful and is usually available at leading medical centers around the country. In addition, people who have been in the military have the option of visiting one of ten Veterans Administration (VA) Hospitals around the country. They stay for several weeks and receive instruction on how to manage their lives and even how to use a computer

In some patients, the ophthalmologist is able to see the presence of a subretinal neovascular membrane, or "net," during a routine examination, but in other patients it is necessary to obtain a fluorescein angiogram (FA) or indocyanine green angiogram (ICG). This test not only confirms the existence of abnormal blood vessel growth, but also determines the precise location of the vessels. Ocular Computerized Tomography (OCT), and ultrasound test is also helpful.

To read about these test click here

Macular disease causes no pain, redness, watering or tearing of the eye. Your ophthalmologist can instruct you on how to test yourself at home. If you detect any changes in your eyesight, such as straight lines appearing wavy or blurred cision, you should see your ophthalmologist.

AMD affects both eyes, but often proceeds faster in one eye than the other. .

Approximately 20 percent of persons with AMD have had a parent with this condition. Therefore, your children should be alerted to the condition.

That depends on the severity of the cataract and also on the severity of your macular disease. Please discuss this further with your ophthalmologist. In general, peripheral but not central vision may be improved for patients with advanced AMD.

Age-related macular degeneration (AMD) involves only the central portion of the retina. Blood pressure and cholesterol should be controlled and one should not smoke.

The ability to see, or "visual acuity" is found by using a system that compares distance vision between the patient and the standard set for normal vision. Separate measures are determined for each eye The first value is the distance the patient can see; the second value is what someone with normal vision can see. For example, if you can see at 100 feet what someone with normal vision can see at 20 feet, then your vision for that eye would be 20/200.

Legal blindness is defined as 20/200 or less visual acuity in the better eye with glasses or a visual field of 20 degrees or less.

Check one eye at a time with reading glasses on. Stare at the dot and make note of its clarity and the straightness of the lines, both horizontal and vertical. If the lines are wavy as in the picture below, see an ophthalmologist.

Amsler Grid

Amsler Grid with AMD