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Doctor lectures on eye disease

Andrew Thagard | Wednesday, March 24, 2004

The South Bend Center for Medical Education kicked off its 10th annual “Mini Medical School Lecture Series” Tuesday with a presentation by Dr. Philip Gabriele titled “Macula Degeneration and Glaucoma.”Macula Degeneration results from a lack of blood flow to the macula or central region of the retina, and is the leading cause of central vision loss in the United States and overall vision loss of the national population over age 85. Glaucoma is the product of increased eye pressure due to stress on the optic nerve. It is the leading cause of blindness in African Americans and the number one source of preventable blindness in this country.”The eye is a glorified camera,” Gabriele said, saying the eye contains a lens in the front, a retina analogous to film in the back and a cable called the optic nerve that transmits these “photos” to the brain. The retina is made up of rods that are sensitive to black and white and cones which sense color. The cones are concentrated at the retina’s center where Macula Degeneration occurs.Vision is a complex and energetically costly process, Gabriele emphasized. A full 20 percent of the brain is devoted to vision and the optic nerve is composed of nearly one million neurons, he said.”The process of seeing uses massive amounts of energy,” Gabriele said. The eye receives the energy and oxygen it needs through blood. If sufficient blood cannot reach the eye, it becomes deprived of oxygen and eventually its photoreceptors, the rods and cones die off.”Your retina is demanding all this oxygen flow to see,” Gabriele said. “The blood flow [isn’t] keeping up with it. First the cells get sick and then they die.”People with increased risk of developing Macula Degeneration include those who have a prevalence of the condition in their family history and people who smoke because it drives down oxygen concentration and raises carbon monoxide levels. People with lighter colored skin are also more susceptible to Macula Degeneration though the exact reasons why are unclear. The condition’s symptoms include blurred central vision, trouble reading and straight lines appearing wavy.The early stage of the disease is referred to as “dry” Macula Degeneration. As the retina becomes increasingly deprived of oxygen it attempts to compensate by releasing angiogenic factor to simulate new blood vessel formation – a condition called “wet” Macula Degeneration. “There’s only one problem,” Gabriele said. “The only time the body makes really good blood vessels is during fetal development.”Vessels produced later in life tend to be leaky, releasing blood under the retina.”It makes a bad situation worse,” Gabriele said. “It actually blocks the blood supply to the retina and leads to [decreased vision].”The dry form of the disease can be controlled to some extent by increasing the intake of zinc, lutein (found in spinach and other green, leafy vegetables) and antioxidants. The “wet” form can be treated with photodynamic therapy in which doctors use lasers to destroy the forming vessels.In addition to treating the disease, Gabriele also emphasized the importance of helping patients to cope with it.”Macula Degeneration isn’t just loss of vision,” he said. “It’s also loss of freedom.”Such consequences, however, are not inevitable and may be curbed with treatment administered by an ophthalmologist.”It used to be thought that as people got old, failing vision was part of it,” Gabriele said. “Nothing could be farther from the truth.”The treatment options for Glaucoma are even more effective, he said.”Loss [of vision] due to Glaucoma is a much bigger shame because it’s much more treatable,” Gabriele said.The eye has an innate pressure to it in order to maintain its round shape. An excess of pressure damages nerves, which leads to a gradual diminishment in a person’s peripheral vision. Gabriele likened this decrease to the reformatting of panoramic movies into the square shape to accommodate televisions in which some of the image is cut off.”This is why Glaucoma is referred to as the silent stealer of vision,” Gabriele said. “The picture just gets smaller.”The more common form of the disease, called “open” Glaucoma exhibits no symptoms until late in its development but can effectively treated if diagnosed by an ophthalmologist. It increases in prevalence among those over age 40 and does have a genetic basis.”Glaucoma does not equal blindness in today’s world,” Gabriele said. “Bilateral blindness due to Glaucoma is extremely rare in the United States if [a person is] treated by an ophthalmologist.”The “Mini Medical School” Lecture series was sponsored by the Medical Education Foundation. The series will continue next Tuesday with a lecture by Dr. Marguerite Shepard titled “Risks and Benefits of Hormone Replacement Therapy.”