Macular degeneration, age-related
Age-related macular degeneration (AMD) is a degenerative disorder of the retina. It appears in older persons and it causes damage to the macula, a small spot near the center of the retina. The macula is the part of the eye needed for sharp, central vision, the region responsible for capturing the forms and details of fundamental tasks like watching television, recognizing objects, reading or distinguishing a face.
Occasionally, and because of age-related factors or tobacco, regulation process loses it efficiency and harmful substances accumulate on the retina, slowly deteriorating the cells of the macula. This process alters the macular function and the patient perceives a progressive vision loss.
In the developed countries, it is the principal cause of "legal" blindness in persons over 55 years of age. World-wide, there are around 25-30 million persons affected by AMD, a number which will increase considerably in the next 25 years because of the aging of the population.
In its early stages, macular degeneration may not have symptoms and may be unrecognized until it progresses or affects both eyes. The first sign of macular degeneration is usually a dim, blurry spot in the middle of the vision, distortion or even loss in the central vision. Some signs of AMD are crooked central vision or the appearance of dark spots.
AMD by itself does not lead to complete blindness, with no ability to see. It does not usually affect peripheral vision. The rest of the retina normally maintains its functions and allows the patient to continue a normal lifestyle.
AMD is a common eye condition and a leading cause of vision loss among people age 50 and older, affecting especially those over 70. In addition to age, which is the main factor, other factors can also cause its development:
- Genetic factors: recent discoveries have detected genes which predisopse the development of macular degeneration
- Family history of macular degeneration
- Race. AMD is more common among Caucasians than among African-Americans or Hispanics/Latinos.
- Smoking. Research shows that smoking triples the risk of AMD.
- Light eye color
- Cardiovascular risk factors: high blood pressure, cholesterol, atherosclerosis, etc.
- Diet: high in fats and low in antioxidents
- High exposure to solar radiation
Unfortunately, there is no preventative treatment for AMD. There are only recommendations that can delay the development of the disease or slow down its progress:
- Diet: Eat healthy and include lots of dark green, leafy vegetables (such as spinach) and less saturated fats. The doctor may also suggest antioxidant vitamins. Eat fish, a good source of omega-3 fatty acids, and antioxidant vitamins (A, C and E, lutein and zeaxanthin and minerals such as copper, zinc, magnesium, manganese) have been shown to, in certain cases protect against the progress of macular degeneration.
- Visit the ophthalmologist regularly after age 60, especially if there is family background of the illness.
- Limit harmful fats. Too much saturated fat and cholesterol in your diet may increase your risk that AMD will get worse.
Vision tests are fundamental in older persons. The vision in both eyes should be check periodically, with tests as simple as covering one eye and then the other and check the differences when looking at a distant object, or by checking with an Amsler grid.
Preventing the evolution of maculopathy to age-related macular degeneration consists of taking measures to prevent choroidal neovascularization (the growth of new blood vessels in the centre of the macula). The only effective preventative measure is to quit smoking since the use of antioxidants such as b-carotene, vitamin C, tocopherol or zinc have not been proven to have a preventative effect. Once maculopathy is established, antioxidant zinc supplements have not been shown to be effective. It has been observed clinically that laser photocoagulation of drusen (yellow deposits under the retina) leads to their disappearance and the retina recovers an almost normal aspect. Unfortunately, and despite the diverse clinical studies carried out varying the protocol slightly, the disappearence of drusa does not reduce the risk of developing choroidal neovascularization.
Gene or region studied