AMD is a multi-factorial eye disease and is the leading cause of central vision blindness in Canada. It results from physical changes to the macula, a portion of the central retina that is responsible for clear, sharp vision, and is located at the back of the eye. Some common symptoms include a gradual loss of ability to see objects clearly, distorted vision, a gradual loss of color vision and a dark or empty area appearing in the center of vision.
There are two types of AMD:
• dry AMD (90% of cases)
• wet AMD (10% of cases)
Dry AMD is the most common type and is a generally progressive and eventually visually debilitating problem. Scientific research – see AREDS – determined certain vitamins and minerals may help prevent or slow the progression of dry AMD. Our eye doctors will recommend a product that will work best for you.
Wet AMD is the less frequent form, but can affect central vision in a more immediate and dramatic way. Symptoms would include a significant drop or distortion in central vision which, in some cases, can occur overnight. Treatment for wet AMD has improved dramatically with new injectable drugs which, in some cases, can arrest or improve visual loss.
Risk factors for AMD include:
• Age – age is the greatest risk factor for AMD. To ensure early detection of all age-related eye conditions, people over the age of 40 are encouraged by our eye doctors to come in for comprehensive eye exams every 1 to 2 years.
• Genetics – new evidence exists that some cases of AMD are hereditary. 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 Behavioural Risk Factors
• 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 second hand 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 AMD, were more than four times as likely to have moderate or severe hypertension as 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.
• 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 o 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.
