Ask the expert – eye protection

Q: I’ve heard that using a weaker prescription for your eyeglasses than you might need helps keep your vision from deteriorating more quickly. Is this a good idea?

A: No, it’s not, says John C. Hagan III, MD, an ophthalmologist in Kansas City, Mo., and editor of Missouri Medicine.

According to Dr. Hagan, the idea that a weaker prescription will slow eye changes is a misconception, one of many that circulate about eyeglasses. Among the most popular myths is “advice” that glasses actually weaken your eyes, or that the wrong lenses will harm you somehow, or that not wearing your glasses will damage your vision. None of these is true. And if you follow any of these ideas, you certainly won’t see as clearly as you could by wearing the lenses your doctor prescribes.

“Trying to influence your eyes by not getting and using the correct prescription for your glasses,” Dr. Hagan says, “is like trying to keep from growing taller by buying clothes that are too small.”

Bottom line: Using weaker glasses than those your physician recommends won’t benefit your eyes at all. You just won’t be able to see as well as you could with the right ones.

Q: If I want to protect my vision, does it make a difference what kind of sunglasses I buy?

A: Indeed it does. You want to make sure you buy glasses that prevent ultraviolet (UV) rays from entering your eyes, says R. G. Shugarman, MD, voluntary professor of ophthalmology at Bascom Palmer Eye Institute at the University of Miami’s Miller School of Medicine. These harmful rays contribute to the formation of cataracts and the development of macular degeneration. UV rays also can cause skin cancers, which are common on eyelids.

Start by looking for sunglasses marked “UV protective.” Luckily, maximum effect doesn’t have anything to do with cost: Some expensive designer models do very little, while some modestly priced ones offer good protection. Lens color doesn’t matter, either. The UV filter is invisible to the eyes but can be measured by a machine at most optical shops where you might get your glasses checked as a courtesy, says Dr. Shugarman.

Your eyes will be safest with sunglasses that have large frames, wrap around your eyes, and fit you well. Before you buy, it’s a good idea to step outside to see how well they work for you against glare and how comfortable they are in bright light. You may want to be sure you can see clearly through them in low light, too.

Q: I’ve just been diagnosed with type 2 diabetes. Should I be doing something special to protect my vision?

A: Type 2 is most common form of diabetes. More than 90% of people with the disease have type 2, which is associated with older age and with being overweight and inactive. High blood glucose (sugar) and high blood pressure from diabetes can damage the tiny blood vessels in the retina (the lining in the back of the eye) and can lead to blindness if the damage isn’t detected early and the disease isn’t properly managed.

According to K. Bailey Freund, MD, clinical assistant professor at New York University’s School of Medicine and attending surgeon at Manhattan Eye, Ear & Throat Hospital, the most important thing you can do for your vision is to work with your primary care doctor to get good control of your blood sugar. This can be accomplished with diet, exercise, and, if necessary, medication. Managing your blood pressure, weight, and cholesterol also helps. The better controlled your blood sugar, the lower your risk for eye complications, Dr. Freund says.

You need to see your eye doctor at least once a year to check for diabetes-related changes. “It is much easier to prevent vision loss than to restore it once the retina has been damaged by poor diabetic control,” he adds.