Macular degeneration, also known as age related macular degeneration (AMD) is a disease of the macula of the eye that is found predominantly in elderly people and is the leading cause of central vision loss in the USA for those over the age of 50 years.
The macula is the central area of the retina of the eye that, if diseased or damaged, results in the inability to read or see fine detail. There are two main types of advanced AMD – dry and wet. The former makes up over 90% of cases and, the less common wet form makes up the remaining 10%.
The cause of dry macular degeneration is the formation of deposits called drusen on the macula. Drusen are fairly common in individuals over 50 years of age and do not cause any visual impairment when found in small numbers. However, when they become larger and more extensive they start to adversely affect vision.
Drusen are yellowish accretions of lipoproteins in the lining of the retina. The cause of AMD and the reasons that drusen form is not entirely clear but there is a relationship with their formation and those of cholesterol deposits in arteries and other parts of the body.
There are a number of important risk factors for AMD:
Oxidative stress: This state is associated with free radical overload and antioxidant deficiency that occurs more frequently with aging. There is convincing evidence that oxidative stress is the underlying cause of AMD as oxidative stress increases with age and is associated with several diseases like diabetes, obesity and others. Inflammation: An inflammatory process is also involved in the formation of drusen and both the dry and wet types of AMD. Age: The older you are the greater your risk of developing AMD. Smoking: Smokers have a higher incidence of AMD. Genetic predisposition: Certain genes have been identified that place some people at increased risk for AMD. Obesity: This is associated with oxidative stress and increased risk for AMD. High blood pressure and high cholesterol levels: Individuals with hypertension and abnormal blood lipid levels have an increased risk for AMD.
Prevention and treatment of AMD with antioxidants
Several very large studies have shown conclusively that those individuals who eat a diet rich in antioxidants have a lower risk of developing AMD. Two of the most comprehensive of these are the Age Related Eye Disease Study and the Blue Mountains Eye Study both of which monitored the diets and examined the eyes of over 3500 participants for at least eight years.
These two studies confirmed earlier research that showed how antioxidants can slow the progression of AMD by up to 35%!
However there were a few important findings that should be noted.
Although these and other studies have provided conclusive evidence that a diet high in antioxidants can protect against the development of macular degeneration, the Blue Mountains Eye Study found that an intake of the antioxidant,
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