February - Age-Related Macular Degeneration Month
The retina of the eye is the layer where light images are converted to visual images. Light sensitive cells are called "photoreceptors", they receive and absorb light rays of different colors and send messages to the brain via nerves (i.e. the optic nerve). These messages add-up to provide people with the images that they see.
Two major portions of the retina participate in the process described above. The peripheral or outer surface deals mainly with black and white images, especially from the top and sides of the image.
The central surface contains a structure, (macula ) that is responsible for color vision. It allows the detection of objects in the center of images.
When there is macular degeneration present, central vision is impaired. Thus, when a person with macular degeneration views an object, it appears as if a black shadow obscures the center of the image. This defect is caused by the degeneration of photoreceptor cells in the macula. Mostly, people with advanced age are afflicted.
When an eye doctor examines the eye, he can detect tiny swollen areas in the macular region and near the optic nerve, which transports images to the brain. When the process causes significant deterioration of the macula, serious visual problems result.
The exact causes of age-related macular degeneration (AMD) are not exactly known, but most people who have AMD are elderly. Treatment of this disease may slow damage but does not usually improve the vision. A prism device can be added to spectacles that change the direction (defraction) of images from the center of the eye to the periphery, where better images can be received. Contrasting enhancing spectacles may also slightly improve vision, and protect against light damage.
Another procedure is strictly experimental. By using animals, it is possible to implant healthy retinal cells into diseased retinas, so as to improve vision. This technique has not yet been applied to humans.
The ophthalmic community looks forward to having better diagnostic and treatment procedures to reduce AMD to a minimum.
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