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Age-related macular degeneration (AMD) is a major cause of visual impairment in the U.S. Age-related macular degeneration (AMD) is a major cause of visual impairment in the United States. As many as 11 million Americans have some form of macular degeneration, including both early and later stages of the wet and dry forms. More than two million people, aged 50 and older, are living with the most advanced forms of the disease.

All wet AMD is considered advanced; however, the dry form of AMD has three stages:

• Early AMD - patients have several small drusen or a few medium-sized drusen. There is no vision loss or symptoms at this stage.
• Intermediate AMD - patients have many medium-sized drusen or one or more large drusen. Some people may need more light for tasks such as reading. A blurry spot may appear in the center of the visual field.
• Advanced AMD - patients exhibit a large number of drusen deposits and a breakdown of RPE and photoreceptor (light sensitive) cells and supporting tissue in the retina. A large blurry spot occurs in the center of the visual field and can become larger and darker, eventually causing a complete loss of central vision.

To help diagnose AMD, an eye care professional will perform a dilated eye exam to view the retina and optic nerve for damage, a visual acuity test to measure sight from various distances and a fundoscopy to examine the back of the eye. If wet AMD is suspected, fluorescein angiography, in which dye is used to detect leaking blood vessels, may also be performed. The patient might be asked to look at Amsler grid; if the straight lines on the grid appear wavy or distorted, AMD may be developing.

The National Eye Institute's Age-Related Eye Disease Study (AREDS) found that taking a specific high dose formula of antioxidants and zinc (500 milligrams of vitamin C, 400 International Units of vitamin E, 15 milligrams of beta-carotene, 80 milligrams of zinc as zinc oxide and two milligrams of copper as cupric oxide) may delay or prevent intermediate AMD from progressing to the advanced stage. There is no evidence, however, that the AREDS formula benefits people with early stage AMD. Patients with intermediate AMD in one or both eyes or advanced AMD (dry or wet) in one eye but not the other eye should consider taking the formula. Consult a physician before taking any supplements because they may be contraindicated for certain medical conditions or may react negatively with some medications.

To discover any changes to your vision as early as possible, your eye care professional will probably have you test your own vision on a regular schedule using a small, hand-held Amsler grid.  He or she may also do this at the office. At home, you will hold the chart at reading distance in good light, cover one eye, and focus on a black dot in the middle of the grid, then repeat with the other eye. If the lines of the grid appear dim, irregular, wavy, or fuzzy, you should schedule an eye exam immediately.

You can download an Amsler grid at www.brightfocus.org/amsler.

Age-related macular degeneration (AMD) typically affects individuals over 50 years old. Scientific evidence shows that genes may play a role in the development of nearly three out of four cases of this devastating eye disease.

Several genes are believed to be strongly associated with the risk of developing AMD:

• Factor H and Factor B genes are responsible for proteins that help regulate inflammation in the part of the immune system that attacks diseased and damaged cells. According to study results published in 2006 by Columbia University, 74 percent of AMD patients carry certain variants in one or both of these genes, and these may significantly increase their risk of developing it.
  
  
• PLEKHA1 – a gene located on chromosome 10; researchers believe it may increase the risk of developing AMD. Like Factors H and B, PLEKHA1 appears to be involved in the cellular processes related to inflammation.
  
  
• LOC387715 – A certain variation of this gene appears to increase the risk of developing AMD. This risk is further heightened if a person with this gene variation also smokes.
  
  
• HTRA1 – Scientists have identified a link between a mutation in this gene and the development of AMD. Specifically, the HTRA1 mutation is thought to be associated with the formation of drusen (yellow deposits of waste products under the retina that are often a sign of dry AMD), and may also promote the growth of fragile new blood vessels typical of wet AMD.
  
  
• Complement C3 – Researchers have found that a variant in this gene increases the risk of developing the wet and dry forms of AMD. This gene plays an important role in the immune system, leading scientists to believe that inflammation is a vital part of the AMD disease process.

Other gene candidates are being studied to determine their role in AMD. While there is definitely a strong genetic component to this disease, it is highly likely that its development is due to a combination of multiple factors including gene mutations or variations and environmental factors such as sunlight exposure, diet and smoking.

It is possible to develop AMD in only one eye. However, as the disease progresses both eyes may become affected. If an individual has macular degeneration in one eye, he or she is more likely to develop it in the other eye than someone who does not.

There are a great many resources available to people with low vision and their caregivers. For instance, every state has an agency on aging. You may find it in the phone book, online, or with the help of a librarian or friend. Professional low-vision therapists at eye clinics or other organizations can assist you. Let your eye doctor know what kind of limitations you are experiencing due to vision loss. He or she can then refer you to a vision rehabilitation center, where a low-vision therapist can work with you to help you adapt and resolve specific problems.

You can also modify your environment, use low-vision aids, develop your senses of hearing and touch, and practice using peripheral vision. Your doctor can prescribe optical devices such as magnifiers. Many non-prescription magnifying glasses and devices are also available to assist with reading and other close work, such as sewing or model-building. These devices range from the simple and inexpensive to more expensive high-tech products that can aid in using computers and watching television.

Many styles of magnifiers, including discreet ones, can be found at drug and medical supply stores, or may be ordered online or by phone through low-vision product catalogs. A hand-held magnifying glass can help with reading medicine bottle labels, mail, price tags in stores, and restaurant menus. Other magnifiers come in the form of eyeglasses or clip onto glasses to free your hands for other activities.

Commonly used household items with large numbers and letters, and others that “talk,” are also available. There are many sources for large-print books and audio materials, as well as services that read newspapers and magazines by phone or over the radio.

Electronic reading aids are proliferating, such as: computer programs that magnify the computer screen and/or read screen text out loud; special scanners to carry while shopping that read out prices, sizes, and colors; web browser plug-ins; and smartphone applications. One specialized device can take pictures of signs or menus and read the words in the pictures aloud.

AMD is a common eye disease associated with aging that gradually destroys sharp, central vision. The retina is the very thin tissue that lines the back of the eye and contains the light-sensing cells that send visual signals to the brain. Sharp, clear, 'straight ahead' vision is processed by the macula, which is the central part of the retina. When the macula is damaged, many daily activities such as driving, reading and recognizing faces become increasingly difficult.

• More light is needed for tasks such as reading
• A blurry spot appears in the center of the visual field
• A blurry spot becomes larger and darker
• Straight lines may appear wavy
• Straight-ahead vision becomes distorted or lost entirely in a short period of time