Macular Degeneration - Risk Factors
Macular Degeneration - What Environmental and Behavioral Factors Increase the Risk?
Researchers have discovered several risk factors that appear to be associated with macular degeneration.
- Cigarette Smoking
- Early Menopause
- Hypertension (high blood pressure) and/or cardiovascular disease
- A diet high in certain vegetable fats, especially those found in snack foods like potato chips
- Prolonged sun exposure
A person’s age is far and away the largest risk factor for macular degeneration. It is estimated that 25% of the population between 65 and 74 have macular degeneration. Above age 75, 33% have macular degeneration.
Cigarette smoking has been implicated as a risk factor for macular degeneration. Two separate studies found that current and former smokers, when compared with people who never smoked, had as much as twice the risk of developing macular degeneration. Unfortunately, in former smokers of one pack or more a day, the risk of developing MD remained elevated even after having quit for more than 15 years. Nonetheless, quitting smoking greatly reduces the risk of developing cigarette-related cancers, emphysema and heart disease.
Estrogen and Early Menopause
Also, researchers are examining the possibility of a link between estrogen production and the onset of age-related macular degeneration in women. Information gathered in recent years indicates there is a higher incidence of macular degeneration in women, and that women who experience earlier onset of menopause may be at greater risk of developing the disease. The National Institutes of Health currently supports a large, three-part study of women’s post-menopausal health issues investigating risk factors for heart disease, osteoporosis, certain types of cancers, and macular degeneration.
Elevated Blood Pressure
Results from a recent epidemiological study suggest that severe macular degeneration is associated with moderate to severe elevations in blood pressure. This study examined blood pressure and cholesterol levels and the use of antihypertensive medication in 644 study participants with and without macular degeneration. Patients with wet macular degeneration were more than 4 times as likely to have moderate to severe hypertension than those without macular degeneration.
Dietary Fat Intake
A recent study found that high intake of monounsaturated, polyunsaturated and vegetable fats was associated with a twofold-increased risk of developing wet macular degeneration. These fats are all commonly found in snack foods such as potato chips, French fries, cakes and commercially prepared pies. High intake of another fat called linoleic acid, found in many snack foods, was associated with the greatest risk of developing wet macular degeneration. In the same study, researchers also found that individuals who consumed little food containing linoleic acid and who ate two or more servings of fish per week showed a lower risk of developing macular degeneration.
Previous studies have found that ultraviolet light exposure can damage cells through a process called oxidative stress. Some researchers have theorized that ultraviolet light exposure may damage the macula and lead to macular degeneration. However, light exposure studies have not yet found a definitive link to the development of macular degeneration. Two studies found that people with histories of prolonged, unprotected exposure to light had more cases of severe macular degeneration than those without such exposure. However, other light exposure studies have not found an association with macular degeneration. Animal studies of intense light exposure find photoreceptor cell damage but none of the disease characteristics common to macular degeneration. In reviewing this research, scientists caution that light exposure studies are difficult to conduct. The relationship between light exposure and AMD deserves further study.
Researchers are also evaluating whether farsightedness (hyperopia), light skin and eye color, cataracts, elevated levels of cholesterol, and race increase the risk of macular degeneration.
What Can I Do About These Risk Factors?
An awareness of environmental risk factors that lead to disease can help patients reduce or eliminate exposures where possible. However, in some cases, risk factors are biological in nature (e.g. early menopause) and cannot be controlled. Nonetheless, if you or a family member have a history of these risk factors, then regular ophthalmology examinations can help detect the disease in its early stages, enabling a patient to seek treatment before serious vision loss occurs.