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Take a look at the retina

Created date

December 31st, 2008

They say "the eyes have it," but which part of the eye has what? Consider, for example, the retina. "The retina is located at the back of your eye. It sends light signals along the optic nerve to the brain, and those signals turn into images," says Douglas Lazzaro, M.D., chairman of the department of ophthalmology at Long Island College Hospital in Brooklyn, N.Y. As we age, the retina can become vulnerable to conditions that can impair or even destroy vision. Floaters, small spots or freckles that move around the field of vision, become more common. They are more likely to be noticed while looking at a white sheet of paper or at a blue sky. Floaters and flashes "Floaters by themselves may be annoying but aren t necessarily dangerous. They should be checked if they appear suddenly or you also see flashes of light. Then you should see an ophthalmologist immediately," Lazzaro says. Floaters can be a signal of a retinal tear. These occur when the fluid in front of the retina (vitreous gel) thickens and shrinks and pulls on the retina. If the vitreous gel seeps through the tear, it can cause the retina to detach from the back of the eye, a condition called posterior vitreous detachment (PVD). PVD develops in two thirds of adults age 70 or older. Retinal detachment can lead to partial or complete vision loss in your eye. "The retina has two types of light receivers: the cones see light and make color interpretations; the rods provide night vision," says Lazzaro. It is in the macula, the middle part of the retina, where the retina s rods and cones are found. Macular degeneration The macula is affected by changes in the area of the retina known as the retinal pigment epithelium (RPE). The RPE helps remove waste from the eye, but as the eye ages, its waste-removing properties become less efficient. Eventually deposits left in the macula cause its vision to deteriorate, a condition called macular degeneration. In macular degeneration, the central portion of your vision becomes cloudy. In most people, once the disintegration has begun, a blind spot develops in the center of the eye. One of the most common side effects of long-term or uncontrolled diabetes is its effect on the retina, called diabetic retinopathy. More than 70% of adults with type 2 (adult onset) diabetes develop this condition. Diabetic retinopathy "There are two types of diabetic retinopathy," Lazzaro says. "Non-proliferative retinopathy is the early stage in which the retina s blood vessels weaken. You may see dark spots at this stage. "In proliferative retinopathy, abnormal blood vessels grow in the retina," he continues. "These blood vessels can bleed into the vitreous, and you ll often also see floaters or dark spots. Ultimately retinal detachment can occur." The retina has no nerves, so you can t feel it tear; you must rely on other symptoms. Signals for retinal tears and detachment include the floaters already mentioned and shadows along your peripheral vision, the ability to see to the sides without moving your eyes. Another signal may be a reduced sense of vision. If you ve had cataract surgery or are extremely nearsighted, you are especially at risk of retinal detachment. Subtle symptoms "I ask specific questions, like how well someone is seeing the street signs off to the side while they re driving. Or I ll observe whether they have trouble reading a pill bottle. These indicate they should see an ophthalmologist," says Mary Norman, M.D. An ophthalmologist is the doctor who should do an initial retinal exam and then determine if you need a retinal specialist. For diabetic retinopathy, diet and exercise are still two of the best ways to keep it from developing or progressing. One study found that keeping your sugar levels controlled with medication decreased the risk of retinopathy by 30%. Lowering your blood pressure (below 130/80) is also recommended, and some experts now also suggest that watching your cholesterol and quitting smoking may help. "People with diabetes should be screened by an ophthalmologist at least annually," Norman says. "If someone has known retinal problems or starts experiencing vision changes, they should be seen more frequently." "For macular degeneration, there are new drugs injected into the eye called anti-VEGF drugs. They block the formation of the waste deposits that sometimes decrease vision," Lazzaro says. There are side effects, so discuss this with your doctor. "For tears and detachment, laser surgery is the best option. It s an office visit and takes about five to seven minutes," Lazzaro says. Depending on how bad the damage is, much of the vision can often be restored. "There can be side effects, though, including increased sensitivity to light," he adds. "If someone has any sudden vision changes, they should see an ophthalmologist immediately," Norman says.