Macular Degeneration, often called AMD or ARMD (Age-Related Macular Degeneration), is the leading cause of vision loss and blindness in people aged 65 and older. Because older people represent an increasingly larger percentage of the general population, vision loss associated with AMD is a growing problem. AMD occurs with degeneration of the macula , which is the part of the retina responsible for the sharp, central vision needed to read or drive. Because the macula primarily is affected in AMD, central vision loss may occur.
Archives of Ophthalmology in 2004 estimated that 1.75 million U.S. residents now have significant symptoms associated with age-related macular degeneration, with that number expected to grow to almost 3 million by 2020.
The macula is a small area in the center of the retina that is responsible for sharp, detailed central vision. Macular degeneration results in a gradual distortion of central vision, and sometimes leads to a central blind spot called a scotoma. When central vision is impaired, you may have difficulty recognizing faces and colors, driving a car, reading print, or doing close handwork, such as sewing or other handcrafts. There are two types of macular degeneration: the dry or atrophic type, and the wet or hemorrhagic type. Dry ARMD is the more common form and the less severe. It is caused by the deterioration of the tissue of the macula. Yellowish deposits called drusen form under the macula, causing it to thin and dry out. There is no known treatment that prevents advanced stages of dry macular degeneration or that can restore the loss of central vision. However, studies have shown that taking specific multivitamins and minerals can possibly delay intermediate ARMD from progressing to advanced stages.
The wet form of ARMD in its advanced stages causes rapid growth of small blood vessels beneath the retina. Affected blood vessels leak blood and other fluid, which form scar tissue that causes vision loss. This wet form can be treated with laser surgery, photodynamic therapy, and injections in the eye, which can slow the rate of vision loss. However, recurrence of vision problems over time is common after treatment.
Is the leading cause of low vision among older people and occurs most frequently among Caucasians
Attacks and weakens the central portion of the eye (the macula) responsible for central vision and essential for making out detail
Results in blurred vision in the center of the eye and can also cause blind spots in your center of vision
Is a very serious condition but does not result in total blindness. In fact, with the help of a Low vision specialist you can learn to use your side vision to read and perform other tasks usually performed by the central part of the eye
ARMD can be detected by a self-test using an Amsler Grid. This self-test is no substitute, however, for regular eye exams.
The pattern of the Amsler grid resembles a checkerboard. Cover one eye and stare at the black dot in the center of the grid. While staring at the dot, you may notice that the straight lines in the pattern appear wavy. You may notice that some of the lines are missing. These may be signs of ARMD.
Besides affecting older populations, AMD appears to occur in whites and females in particular. The disease also can result as a side effect of some drugs, and it appears to run in families. New evidence strongly suggests that smoking is high on the list of risk factors for macular degeneration. Other risk factors for AMD include having a family member with AMD, high blood pressure, lighter eye color, and obesity. Some researchers believe that over-exposure to sunlight also may be a contributing factor in development of macular degeneration, but this theory has not been proven conclusively. High levels of dietary fat also may be a risk factor for developing AMD.
Indians by their genetic make up are less prone as compared to their white counterparts to this disease.
The American Academy of Ophthalmology notes that findings regarding AMD and risk factors have been contradictory, depending on the study. The only risk factors consistently found in studies to be associated with the eye disease are aging and smoking.
Aging: Significant vision loss accompanying more advanced forms of AMD increases from fewer than 1% among individuals in their 60s to more than 15% among people in their 90s, according to the Feb. 17, 2004 edition of Canadian Medical Association Journal (CMAJ).
Smoking: Smoking is a major risk factor found in one British study to be directly associated with about 25% of AMD cases causing severe vision loss. The British Journal of Ophthalmology in early 2006 also reported study findings showing that people living with a smoker double their risk of developing AMD.
Heredity: Recent studies have found that specific variants of two different genes are present in most people who have macular degeneration [See “What Causes Macular Degeneration” above]. Studies of fraternal and identical twins may also demonstrate that heredity is a factor in who develops AMD and how severe it becomes.
High Blood Pressure (Hypertension): In September 2003, Investigative Ophthalmology and Vision Science reported a study in Rotterdam, The Netherlands demonstrating that high blood pressure may be associated with development of macular degeneration.
Obesity and Inactivity: Overweight patients with macular degeneration had more than double the risk of developing advanced forms of macular degeneration compared with people of normal body weight, according to one study reported in the June 2003 issue of Archives of Ophthalmology. In the same study, those who performed vigorous activity at least three times weekly reduced their risk of developing advanced AMD compared with inactive patients.
Lighter Eye Color: Because macular degeneration long has been thought to occur more often in lighter skinned populations, particularly in people with light eye color, some researchers theorized that the extra pigment found in darker eyes was a protective factor against development of the eye disease during sun exposure. But no conclusive evidence as yet has linked excessive sun exposure to development of AMD. A small study reported in January 2006 in the British Journal of Ophthalmology found no connection between the eye disease and sun exposure. In fact, the same study found no relation at all between lighter eye color, hair color, and AMD. That finding is contradicted by several earlier studies indicating that lighter skin and eyes are associated with a greater prevalence of AMD.
Drug Side Effects: Some cases of macular degeneration can be induced from side effects of toxic drugs such as Aralen (chloroquine, an anti-malarial drug) or phenothiazine. Phenothiazine is a class of anti-psychotic drugs, including brand names of Thorazine (chlorpromazine, which is also used to treat nausea and vomiting, and intractable hiccups), Mellaril (thioridazine), Prolixin (fluphenazine), Trilafon (perphenazine) and Stelazine (trifluoperaz).
Although much progress has been made recently in macular degeneration treatment research, complete recovery of vision lost to AMD probably is unlikely. Your eye doctor may ask you to check your vision regularly with an Amsler grid. Viewing the Amsler grid separately with each eye helps you monitor your vision loss. The Amsler grid is a very sensitive test that typically reveals clinical findings before the doctor can actually see physical findings. For those who have suffered vision loss, many low vision devices are available to help improve vision by using magnifying lenses and bright lights. Some low vision aids shift images to the periphery for clearer vision.
There is as yet no outright cure for macular degeneration, but some treatments may delay its progression or even improve vision. Treatments for macular degeneration depend on whether the disease is in its early stage or dry form or more advanced, wet form that can lead to serious vision loss. There are no recognized /approved treatments for dry macular degeneration, although nutritional intervention may be valuable in preventing its progression to the more advanced, wet form. For wet AMD, treatments aimed at stopping abnormal blood vessel growth include approved drugs of Lucentis, Macugen, and Visudyne used with Photodynamic Therapy or PDT. Lucentis has been shown to improve vision in a significant number of people with macular degeneration.
Many researchers and eye care practitioners believe that certain nutrients — zinc, lutein, zeaxanthin and vitamins A, C and E — help lower the risk for AMD or slow down the progression of dry macular degeneration. Benefits of high levels of antioxidants and zinc for halting or slowing development of macular degeneration have been widely reported based on results released in 2001 from the Age-Related Eye Disease Study (AREDS) conducted by the National Eye Institute,Phase two of the AREDS study began in late 2005 to evaluate whether similar protective effects against AMD might be associated with other nutrients such as omega-3 fatty acids or “good fats,” and lutein and zeaxanthin found in green, leafy vegetables. The August 2001 issue of Archives of Ophthalmology reported findings that consumption of omega-3 fatty acids, which are particularly prevalent in cold-water fish, also had a protective effect against advanced macular degeneration. Meanwhile, consumption of omega-6 fatty acids, prevalent in vegetable oils, was associated with an increased risk of developing AMD.