Dry Macular Degeneration
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Dry macular degeneration is the most common form of macular degeneration, accounting for 90 percent of diagnosed cases. Both eyes are usually affected, although in some cases only one eye may lose vision. In the dry form the light sensitive cells of the macula slowly break down. The macula is the central part of the retina responsible for sharp, clear straight-ahead vision, color and fine detail. Damage to the macula causes blurring or spotty loss of central vision. In dry macular degeneration, yellowish cellular deposits called drusen (extracellular waste products from metabolism) form under the retina between the retinal pigmented epithelium (RPE) layer and Bruch's membrane, which supports the retina. An increase in the size and number of drusen is associated with the death of RPE and photoreceptor cells (those that “see” light), and is often the first sign of dry macular degeneration.
Glossary of Terms
Bruch's membrane - located in the retina between the choroid and retinal pigmented epithelium (RPE) layer; provides support to the retina and functions as the 'basement' membrane of the RPE layer.
Choroid - layer of the eye behind the retina; contains blood vessels that nourish the retina.
Cones - the photoreceptor nerve cells present in the macula and concentrated in the fovea (the very center of the macula); enable people to see fine detail and color.
Drusen - deposits of yellowish extracellular waste products that accumulate within and beneath the retinal pigmented epithelium (RPE) layer.
Fovea - the pit or depression at the center of the macula that provides greatest visual acuity.
Macula - the portion of the eye at the center of the retina that processes sharp, clear, straight-ahead vision.
Photoreceptors - the light sensing nerve cells (rods and cones) located in the retina.
Retina - the light sensitive layer of tissue that lines the back of the eye.
Retinal Pigmented Epithelium (RPE) - a layer of cells that protects and nourishes the retina, removes waste products, prevents new blood vessel growth into the retinal layer and absorbs light not absorbed by the photoreceptor cells; these actions prevent the scattering of the light and enhance clarity of vision.
Rods - photoreceptor nerve cells in the eyes that are sensitive to low light levels and are present in the retina, but outside the macula.
Sclera - the tough outer coat that protects the entire eyeball.
The following medical illustrations can provide you with more information:
Last Review: 04/26/13