AMD RISK FACTORS
Although researchers do not have a definitive picture of what causes AMD, aging processes are clearly important. A number of additional factors that may put a person at greater risk for developing AMD have been identified.
Age – By definition, age is the greatest risk factor for AMD. An estimated, 1.75 million Americans age 40 years and older have advanced dry or wet AMD. The prevalence increases dramatically with age, with more than 15 percent of Caucasian women 80 years and older having advanced AMD.34 To ensure early detection of all age-related eye conditions, people over the age of 40 are encouraged to see an ophthalmologist for comprehensive eye exams every two to four years.
Genetics - New evidence exists that some cases of AMD are hereditary. Recent reports have shown that as many as 43% of patients with AMD have a genetic mutation in the Complement factor H gene.17-19 Complement Factor H is involved in the control of inflammation in the body and those patients with this genetic trait may be at higher risk from inflammatory induced damage to the retinal pigment epithelium. AMD may be a group of diseases that require different approaches to treatment. For that reason, because early stages of the disease are often asymptomatic and because both wet and dry AMD can progress, everyone over the age of 50, even those without a family history of the disease, should have their eyes checked regularly.
Environmental and Behavioral Risk Factors
Several factors have been identified as having a possible relationship to AMD.
Cigarette smoking – Studies have found that current and former smokers had as much as twice the risk of developing AMD as non-smokers. Although long-term advantages of smoking cessation are not yet known, people with AMD may be well advised to stop smoking. Exposure to secondhand smoke also contributes to the risk of developing AMD.
High blood pressure – Severe AMD has been associated with moderate to severe elevations in blood pressure, according to a recent epidemiological study, which found that patients with wet (exudative or neovascular) AMD, the more severe form, were more than four times as likely to have moderate or severe hypertension than patients without AMD. Additionally, cardiovascular disease, in general, appears to be associated with increased risk of AMD.
Overexposure in sunlight – It has been suggested that exposure to sunlight might damage the macula and cause AMD. Studies to support this theory have been inconclusive thus far and additional studies are under way. Nonetheless, ophthalmologists recommend protecting eyes from the sun and other UV light for a variety of benefits.
Diet – Research on the link between diet and AMD risk has shown that intake of a variety of food types may alter the risk of developing AMD. For example, high consumption of linoleic acid, monounsaturated, polyunsaturated and vegetable fats – fats commonly found in many snack foods – was associated with double the risk of developing wet AMD. Researchers also found that people with limited intake of linoleic acid and who ate two or more servings of fish that is high in Omega 3 fatty acids per week had a lower risk for developing AMD. Other studies have shown that intake of fruits may reduce the risk of AMD, as would diets rich in carotenoids, such as lutein and zeaxanthin, found in dark green leafy vegetables and some berries. These data are not conclusive, however, and may not translate into recommendations.
Estrogen and early menopause – Studies suggest a higher incidence of AMD in women, particularly in women who experience earlier onset of menopause, which suggests that estrogen may play a protective role in minimizing AMD risk.
Other Possible Risk Factors
In addition to the above risk factors, researchers are looking at hyperopia (farsightedness), light skin and eye coloring, cataract surgery, high blood cholesterol levels and race as possible factors that increase the risk of developing AMD.