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Age-related macular degeneration

Donald Sangster first realised that something was wrong with his eyesight when he noticed straight sided objects such as light poles appeared to be wavy. His wobbly vision first affected one eye and then eventually the other. Donald spoke about his concerns with his GP who referred him to a specialist eye clinic where he was diagnosed with “dry type” age-related macular degeneration or AMD.

There are two basic types of macular degeneration: "dry" and "wet." Around 85% to 90% of the cases of macular degeneration are the "dry" type (also called atrophic) "Dry" age-related macular degeneration does not mean that the eyes are dry, but rather that the condition does not involve any leakage of blood or serum from the vessels at the back of the eye as happens in the “wet” type.

Wet macular degeneration

The dry type of macular degeneration is the much more common of the two. It tends to progress more slowly than the "wet" type. However, some people with the "dry" type of macular degeneration can develop the "wet" with the passage of time.

There is no cure for the "dry" type of macular degeneration. “I’ve got the dry type of AMD”, says Donald, “you can do something about the wet type, with Lucentis but with the dry type there’s nothing you can do.”

In both types of AMD, loss of vision occurs within the centre of the visual field. As the condition progresses, the patient sees a grey or black cloud in the centre of the eye. Patients with the "dry" form may have good central vision but it still may be difficult for them to function because their vision fluctuates and they often have difficulty reading or driving. They may also have limited vision at night or other under conditions of low light.

Dry macular degeneration

In the "dry" type of macular degeneration, the retina deteriorates because of the formation of small yellow deposits, known as drusen, under the macula. The macula is a small (5mm) oval-shaped yellow spot near the centre of the retina. Near its centre is the fovea, a pit that contains the largest concentration of cone cells in the eye and is responsible for central, high resolution vision. These deposits dry out and thin the macula and the retina and eventually the macula stops working.

A person with early stage age related macular degeneration usually has minimal visual impairment and but the eye or eyes will have large drusen and the macula will appear to have changed colour. Nearly all people over the age of 50 years have at least one small druse in one or both eyes.

Despite Donald’s loss of vision, he is still able to live at his home in Scotland. His doctor has told him that his condition is stable for now and he has managed to adapt to his condition. While he hasn’t been able to drive for the last 10 years, UK servicemen’s charity St Dunstan’s provided him with assistance for reading and other tasks in the form of a big screen magnifier.

http://www.st-dunstans.org.uk

References:

“Dry Macular Degeneration” American Macular Degeneration Foundation www.macular.org/dry.html, Accessed August 17, 2011

“Macula of retina” www.wikipedia.org/Macula_of_retina, Accessed August 17, 2011