Care of the Eyes Demands Diligence
READING in poor light, sitting too close to the TV, wearing the wrong prescription glasses and crossing your eyes — things your mother warned you would ruin your vision — are actually generally harmless. But a truly dangerous false belief is that there is nothing you can do to prevent the loss of vision.
According to Dr. Paul R. Lichter, a professor of ophthalmology and director of the Kellogg Eye Center at the University of Michigan in Ann Arbor, seeing an ophthalmologist regularly is essential, and not just to get a new pair of glasses. “In the way of preserving your sight,” he said, “it’s making sure you don’t have any hidden eye diseases.”
Dr. Lichter recommends an ophthalmologist’s examination before a child enters school, and if everything looks good at that point, then an exam every five years is enough. But it should be a thorough exam in which the doctor dilates the pupils and examines the optic nerve.
Although there are many eye diseases, there are three that together affect more than 10 percent of the United States population: an estimated 2.2 million people have glaucoma, more than 26 million have cataracts or related lens problems, and 2 million have macular degeneration.
Glaucoma is a group of diseases that cause damage to the optic nerve. The most common is primary open-angle glaucoma, in which the eye’s drainage canals are partly clogged. Most people have no symptoms, and the disease causes a gradual loss of vision. But if it is caught early enough, it can be treated successfully with medication or surgery.
A test for pressure inside the eye, or intraocular pressure, is one way to screen for the disease, but people with normal pressure can still have glaucoma. An examination of the optic nerve is the only sure way to tell.
Narrow-angle glaucoma, sometimes called angle-closure glaucoma, is much less common. This happens when the drainage canals become completely blocked, and symptoms can be vivid — blurred vision, headaches, eye pain and nausea. The usual treatment is surgery.
By the time people reach their 40s they begin to develop presbyopia, a natural part of aging in which the lens of the eye stiffens so that it cannot change shape enough to give the proper focus; the usual remedy is to buy reading glasses.
Sometimes, people run to the eye doctor when this problem crops up, and that can be a good thing, because by this age eye diseases become more common, and, Dr. Lichter said, exams every three years should be routine.
Age-related cataracts can start as early as the 40s, but it is most often after age 60 that such clouding of the lens begins to affect vision. The treatment is to remove the clouded lens and replace it with a permanent plastic lens. At one time, cataracts were removed only when they became intolerable, but with the development of effective permanent artificial lenses, Dr. Lichter said, people with otherwise healthy eyes should have cataracts removed as soon as they become bothersome.
After age 50, an exam every two years is recommended to search for, among other things, signs of age-related macular degeneration, a leading cause of blindness in older people. This disease is caused by hardening of arteries in the macula, the light-sensitive tissue in the center of the retina. It causes no pain, but as the cells in the macula die, vision in the central part of the eye can deteriorate quickly, but usually it happens so slowly that people notice little change.
While medications and laser surgery are effective for the wet form of the disease, in which delicate new vessels grow and then easily break and bleed, the more common dry form is very difficult to treat. Still, Dr. Lichter said, “It’s important for patients to know if they have the signs of the disease, even in its more common dry form, so that they can be advised about signs to look for that might warrant treatment. Considerable research into macular degeneration holds promise for future success in treating the disease.”
As for maintaining healthy eyes, diet and exercise are important, said Dr. James C. Tsai, chairman of the department of ophthalmology at Yale. Carrots, yes, really are effective — they have high levels of beta carotene, which can be converted into vitamin A, needed for good night vision.
Vitamins C and E and omega-3 fatty acids may reduce the risk of cataracts and prevent worsening of macular degeneration, and aerobic exercise can lower pressure in the eye. Smoking and excessive sun exposure increase the risk both for cataracts and macular degeneration. As for good diet, Dr. Tsai said, “It’s what your mother told you: fruits and vegetables.”
For routine preventive measures, Dr. Lichter suggests sunglasses and hats for protection against ultraviolet rays and safety goggles for yardwork and other activities that might endanger the eyes with flying objects. As for over-the-counter eyedrops for people who have no eye-related medical condition, he said: “They are typically a waste of money. Most people buying these things don’t get anything from them.”