Human eye cross-sectional view. Courtesy NIH National Eye Institute
Normal vision. Courtesy NIH National Eye Institute
The same view with age-related macular deneneration.

Macular degeneration is a medical condition where the light sensing cells in the macula malfunction and over time cease to work. It is the main cause of central vision loss (blindness) in the USA today for those over the age of fifty (Americam Academy of Ophthalmology). There are two basic types of the disease: Standard Macular Degeneration (MD) and Age Related Macular Degeneration (ARMD), with ARMD being the most common form of the condition. Macular degeneration that is not age related is most commonly caused by a heredity condition. These forms are sometimes called Juvenile macular degeneration (JMD). In macular degeneration the final form results in complete blindness in the central part of the patient's vision.

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Age related macular degeneration[edit]

ARMD is further divided into a "dry," or nonexudative, form and a "wet," or exudative, form. Eighty five to ninety percent of cases are categorized as "dry" macular degeneration where fatty tissue, known as drusen, will slowly build up behind the retina. Ten to fifteen percent of cases involve the growth of abnormal blood vessels under the retina. These cases are called "wet" macular degeneration due to the leakage of blood and other fluid from behind the retina into the eye. Wet macular degeneration usually begins as the dry form. If allowed to continue without treatment it will completely destroy the macula. Medical, photodynamic, laser photocoagulation and laser treatment of wet macular degeneration are available.

Risk Factors for Age Related Macular Degeneration[edit]

High fat intake is associated with an increased risk of macular degeneration in both women and men. Fat provides about 42 percent of the calories in the average American diet. A diet that derives closer to 20-25 percent of total calories from fat is probably healthier. Reducing fat intake to this level means cutting down greatly on consumption of red meats and dairy products such as milk, cheese, and butter. Eating more cold-water fish (at least twice weekly), rather than red meats and eating any type of nuts may help macular degeneration patients.(Reference: Macular degeneration Types and Risk Factors.

Typical Symptoms[edit]

Amsler Grid Test is one of the most simple and effective methods for patients to monitor the health of the macula. The Amsler Grid is essentially a pattern of intersecting lines (identical to graph paper) with a black dot in the middle. The central black dot is used for fixation (a place for the eye to stare at).With normal vision, if you look at the grid and fix your gaze on the central black dot, all lines surrounding the black dot will look straight and evenly spaced with no missing or odd looking areas. When there is disease affecting the macula, as in macular degeneration, the lines can look bent, distorted and/or missing. Treatment and vision preservation in macular degeneration is facilitated by early detection of the disease. The traditional Amsler grid test is a black and white pattern that may miss early defects ( references at www.ixm.us ), therefore a more sensitive blue on yellow Amsler grid test pattern has recently been introduced (Home Amsler Color Test).

It is important to understand that 'vision loss' or 'blindness' in macular degeneration refers to the loss of 'central vision' only. The peripheral vision is preserved. Blindness in macular degeneration does not mean 'inability to see light' and even with far advanced macular degeneration the peripheral retina allows for useful vision.
The loss of central vision profoundly effects visual functioning. It is not possible, for example, to read without central vision. Pictures which attempt to depict the central visual loss of macular degeneration with a black spot do not really do justice to the devasting nature of the visual loss This can be demonstrated by printing leters 6 inches high on a piece of paper and attempting to identify them while looking straight ahead and holding the paper slightly to the side. Most people find this surprisingly difficult to do.

Juvenille macular degeneration[edit]

"Macular degeneration" is a descriptive term for any condition which leads to loss of function of the light sensitive cells at the center of the retina. Several rare hereditary conditions can lead to macular degeneration in children and adolescents. These include:


Research on Prevention of AMD[edit]

Several macular degeneration clinical trials are currently underway. The most promising approach is the anti-angiogenesis treatment for wet macular degeneration. Different anti-angiogenesis strategies that block VEGF mediated choroidal neovascularization are being evaluated in clinical trials. Examples of such drugs include: Macugen (FDA approved), Lucentis, Retaane, Evizon and siRNA. Radiation therapy (Brachytherapy) and Rheopheresis are also being evaluated for wet macular degeneration.(Reference: Macular degeneration clinical trials). Recent studies suggest that Statins, a family of drugs used for reducing cholesterol levels, may be effective in prevention of AMD, and in slowing its progression. See http://bjo.bmjjournals.com/cgi/content/full/88/2/161

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