By Eric W. Fitz, MD | Retinal Specialist & Ophthalmology
Age Related Macular Degeneration (abbreviated AMD) is the leading cause of vision loss in Americans over 65. AMD is found in more than 10 million Americans.
The disease occurs in the light-sensitive layers that form the back of the eye— the retina and the retinal pigment epithelium. Over time, AMD may cause the central vision to appear distorted, blurry, or absent. This distorted vision has a significant impact on patient’s functional status and quality of life. Visual impairment limits the ability to read or to safely drive a car and is associated with increased rates of falls and hip fractures.
AMD is estimated to affect more than 6.5% of Americans over 40. The disease is more common in people as they age: as Americans continue to live longer, AMD is becoming more prevalent and a greater public health concern. Older Americans are at the highest risk. Up to 15% of Caucasian women over 80 will have vision loss from AMD.
The disease is classified into two forms: “Wet” or neovascular AMD in which abnormal circulation develops underneath or within the retina, and “Dry” or atrophic AMD in which vision is lost to an accumulation of metabolic waste product underneath the retina. Atrophic AMD makes up 85-90% of the cases, with neovascular AMD constituting 10-15%. The disease commonly affects both eyes, albeit with a variable severity in each eye. In some cases, previously dry AMD may progress to the wet type.
The exact causes of AMD have not been established. Genetics, race and lifestyle choices all play a role in determining who develops AMD. People with a family history, Caucasian ancestry, or a history of smoking are at higher risk.
AMD is diagnosed by a doctor specializing in eye disease. Many patients will have symptoms suggestive of the disease, like distorted or wavy central vision. These patients should seek medical attention urgently. However, some patients can be diagnosed before they have any symptoms. To facilitate early diagnosis of eye disease, the American Academy of Ophthalmology recommends a comprehensive eye examination for all adults, with a first exam at age 40 for individuals without a family history of eye disease. Individuals with vision problems or with a family history of eye disease should see a doctor at an earlier age.
The doctor will perform a full exam of the eyes, which includes a dilated exam to assess the retina. Individuals with AMD have abnormal findings in their retina in a central area known as the macula. Drusen, or yellow deposits, are the hallmark finding in atrophic AMD and may be associated with darker spots as the Retinal Pigment Epithelium becomes involved. Patients with wet AMD will have bleeding or swelling in their retina.
Early, dry AMD may be managed by a comprehensive Eye care provider, while more advanced cases are usually referred to an Ophthalmologist who specializes in care for retinal diseases.
In an initial exam, a retina specialist will perform specialized tests to classify the AMD.
These tests may include photographs, angiography of the retina or an Optical Coherence Tomography scan to search for subtle swelling in the macula. All tests, and most treatments, can be performed in the office.
There is no cure for either type of AMD. Fortunately, tobacco avoidance, healthy diet, and judicious use of supplements can reduce the chance of developing AMD. Prevention of dry AMD is vital as there is currently no therapy that can restore vision once lost.
The National Institute of Health has studied prevention of vision loss from AMD in a trial called the Age-Related Eye Disease Study (AREDS) and its follow up, the AREDS 2. These trials established vitamin therapy as beneficial. Individuals with early AMD can have a nearly 25% reduction in their risk of progressive disease over five years if they are treated with a blend of anti-oxidants, macular carotenoids and minerals — specifically Vitamin C 500 mg, Vitamin E 400 IU, Zinc Oxide 80 mg, Cupric Oxide 2 mg, Lutein 10 mg, and Zeaxanthin 2 mg. This blend is known as the AREDS 2 formula and is sold under multiple brand names including Preservision and I-Caps. The formula was not studied in people without AMD, and not shown to be useful for individuals who already had the advanced disease in both eyes.
Multiple additional studies have shown the benefit of lifestyle choices for prevention of AMD. Tobacco avoidance provides one of the biggest risk reductions. Quitting smoking is the most beneficial choice that a smoker can make. While studies of fish oil supplements (1,000 mg daily of omega-3 fatty acids) showed no conclusive benefit, studies of diet have suggested that most people would benefit from eating fatty fish at least twice a week. Wild caught Salmon, Anchovies, Bluefin Tuna, Herring, Mackerel, Sardines, or Trout are all good choices. Additionally, frequent consumption of dark leafy, green vegetables can be protective: these foods include kale, spinach, chard and collard or turnip greens. Adopting a Mediterranean Diet that emphasizes vegetables, legumes, fish, whole grains, and fruits seems to be protective against AMD.
Currently, Wet AMD is treated with medications that can either prevent ongoing loss of vision or restore vision that has been lost. These medicines inhibit the Vascular Endothelial Growth Factor and are referred to as anti-VEGF. The typical treatment course consists of a series of injections of medication into the eye. The injections are given once monthly at the onset of therapy, but the interval between treatments may be extended once the disease has responded. There are four different injections available (Macugen, Lucentis, Avastin, and Eylea) and the choice of agent is tailored to the particular patient. Therapy is ongoing in most patients. Previous treatments for wet AMD have included thermal laser photocoagulation and Photodynamic Therapy. Many new drugs and treatment strategies are under investigation.
AMD is a critical health problem affecting Americans as they age. Fortunately, many advances have been made in the care of patients with AMD. Avoiding tobacco and eating a Mediterranean diet rich in fish and vegetables is the best primary prevention strategy. Early diagnosis and early treatment after the onset of disease can prevent loss of vision. Preservation of vision averts the loss of independence and function that many American seniors once had to endure.