Current Course Topic:
Macular degeneration is the gradual loss of vision caused by the oxidation of the macula, which is a small, circular membrane at the center of the retina. This membrane is light sensitive and responsible for our central vision. When the macula degenerates, central vision deteriorates, resulting in dark spots and cloudiness. This disease is the most common cause of blindness in people over 50.
It is caused by the oxidation of the macula. As the arteries harden with age, the delicate structures of the eye begin to lose some of their function. The condition may be aggravated by factors such as smoking, cardiovascular disease, exposure to sunlight, high blood pressure, high cholesterol, diabetes, or poor diet. Heredity may also influence the development of macular degeneration. The condition is very rare before age 50.
The two types of age-related macular degeneration (AMD, for short) are Wet-type (neo-vascular) and Dry-type (non-neovascular). Dry type AMD is the most common and is responsible for approximately 80% of all cases. It is caused by the shrinking and pigmentation of retinal tissue. The onset of dry-type AMD is very gradual and may not be noticed until it is in an advanced stage. In contrast, wet-type AMD is caused by the over-growth of new blood vessels behind the macula, which can easily break and bleed onto the macula. The material that settles on the macula is called "exudate". The body eventually reabsorbs the exudate, but a scar develops on the macula. Although wet-type AMD makes up only 20% of AMD cases, it is responsible for about 90% of the blindness caused by this disease. Wet-type AMD more rapidly causes blindness than dry-type.
| Healthy Macula | Dry Macular Degeneration | Wet Macular Degeneration |
|---|---|---|
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Wet-type macular degeneration is the only type that is treatable, though only about 15-20% of cases are operable. The most common treatment for wet AMD is photodynamic therapy (PDT), which uses a light sensitive drug called Visudyne. In addition, a new treatment is Macugen, a drug injected into the eye that stops the growth of the blood vessels that cause the damage in wet AMD. At this time, dry-type AMD is incurable and untreatable. Wearing sunglasses and maintaining a healthy lifestyle with a diet rich in dark green vegetables may help to prevent the disease.