While dry macular degeneration accounts for 80-90 percent of patients seen in retinal practices, according to Janet Sunness, M.D., head of Hoover Low Vision Services at the Greater Baltimore Area, about “3.5% of the U.S. population age 75 and older have geographic atrophy. In people older than 90, the percentage is 22%.”

Geographic atrophy is an advanced form of dry AMD. It is the dying of the cells in the Retinal Pigment Epithelium (RPE) – one of the layers of the macula. It is the loss of these cells that results in the de-pigmentation of this retinal layer. During a retina exam the de-pigmented area will show up as an irregular white spot.

The RPE is responsible for nourishing the photoreceptor cells – the rods and cones. So when the RPE atrophies or looses cells, the underlying photoreceptor cells don’t get nourished and consequently they degenerate and die. With less cone cells and rods cells there is loss of vision – colors aren’t as vivid, objects aren’t as distinct, and more light is needed for reading. The area of atrophy where there are no cells to provide messages to the brain, results in what is called a scotoma. Because the macula is responsible for our central vision the correlating loss of cells in that area results in a loss of vision right in the middle – not the sides or periphery – but straight ahead – the vision that is needed to recognize a face or to read a book or look at a picture. So instead of seeing the face of a person, one will see a blurry, gray or black spot called a scotoma. The size of the central scotoma is different for each person. But as geographic atrophy advances the scotoma gets larger.

This process of atrophy or degeneration is a slow process – unlike wet AMD when a sudden burst of blood vessels floods the photoreceptor cells causing a sudden loss of vision. Dr. Sunness says that more than half of patients with GA in one eye develop GA in the other eye. Currently there is no standard treatment, but several clinical trials have emerged in the last couple of years looking at risk factors, reasons for progression, and therapies to slow the vision loss.

Meanwhile there are many ways a person can adapt to these vision losses resulting from GA through brighter and better lighting, bigger print material, and bolder colors for contrast. For suggestions on vision aids for those with AMD go to:

Visual Aids for Advance Macular Degeneration

Leslie Degner, RN, BSN
www.WebRN-MacularDegenera