Macular Degeneration

There are two forms of macular degeneration: dry and wet. It is possible for a person to suffer from both forms, for it to affect one or both eyes, and for the disease to progress slowly or rapidly. Dry macular degeneration may advance and cause loss of vision without turning into the wet form of the disease. However, it is also possible for the early-stage dry form to change into the wet form of macular degeneration.

The dry form of macular degeneration is the most common type of macular degeneration. This form, in which the photosensitive cells of the macula slowly break down, is diagnosed in 85-90 percent of cases. Yellow deposits called drusen (extracellular waste products from metabolism) form and accumulate under the retina between the retinal pigmented epithelium (RPE) layer and the Bruch's membrane, which supports the retina. Drusen are often found in the eyes of older people, but an increase in the size and number of these deposits is frequently the first sign of macular degeneration. Over time, drusen are associated with deterioration of the macula and the death of RPE and photoreceptor cells, resulting in a blurring or spotty loss of clear, straight-ahead vision.

The dry form of macular degeneration has three stages:

1. Early - patients have several small drusen or a few medium-sized drusen. There is no vision loss or symptoms at this stage.

2. Intermediate - patients have many medium-sized drusen or one or more large drusen. Some people may need more light for tasks such as reading. A blurry spot may appear in the center of the visual field.

3. Advanced - patients exhibit a large number of drusen deposits, and a breakdown of RPE, photoreceptor (light sensitive) cells, and supporting tissue in the retina. A large blurry spot occurs in the center of the visual field and can become larger and darker, eventually causing a complete loss of central vision.

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