Age Related Macular Degeneration

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Macular degeneration

Macular degeneration is caused by hardening of the arteries that nourish the retina.  This deprives the sensitive retinal tissue of oxygen and nutrients that it needs to function and thrive.  As a result central vision deteriorates. 

There are two main types of AMD.  Dry and Wet

The central portion of the human retina contains a yellow pigment called the macular pigment. This pigment helps protect the sensitive receptors in the retina, particularly from the potentially harmful effects of blue light. Macular pigment can only be made in the eye from the food we eat. The density of the pigment has been shown to be linked to the type of diet and is reduced in those who smoke. 
There are two main types of AMD: the "dry" form and the "wet" form, based on the absence or the presence of abnormal growth of blood vessels under the retina. Most people with AMD have the dry form. 

Currently there is no proven treatment for the dry type, but the loss of vision tends to be milder and the disease progression is rather slow.  Recent research has shown that it's progress may be slowed by altering lifestyle, for example by stopping smoking and increasing macular pigment levels.

Approximately 15% of patients with AMD have the wet form, where there is a growth of abnormal blood vessels under the retina, which can cause leakage, bleeding, and scarring, resulting in more rapid and severe vision loss. About 80% of severe vision loss is due to the wet form as compared to 20% due to the dry form. 

The wet form can manifest in two types: classic or occult. Over 70% of patients with the wet form have the occult type. So far, only the classic wet type is treated with conventional laser photocoagulation to stabilize vision or to limit the growth of abnormal blood vessels. The remaining majority of patients with wet AMD cannot be treated with the laser procedure. Also, the current laser treatment does not improve vision in most treated eyes because the laser destroys not only the abnormal blood vessel but also the overlying macula. Better treatment options are obviously needed.