Researchers have established a link between ultraviolet (UV) radiation and eye damage — particularly cataracts and age-related macular degeneration. Wearing sunglasses is the easiest way to protect your eyes from the hazardous radiation of the sun. They needn’t bear a designer label or cost hundreds of dollars to do their job properly.

When shopping for the right pair of sunglasses, consider which type suits you best based on how you’ll be using them:

• For daily wear: Look for lightly tinted glasses that block 70% of UVB rays, 20% of UVA, and 60% of visible light. The American National Standards Institute (ANSI) categorizes these glasses as “cosmetic.”
• For outdoor recreation: Medium to dark lenses are fine for most outdoor activities. They should block 95% of UVB, 60% of UVA, and 60% to 90% of visible light. ANSI categorizes these glasses as “general purpose.” Most sunglasses fall into this category.
• For very bright conditions: When heading for the beach or ski slopes, choose extremely dark glasses with UV blockers. The label should indicate that the lenses block 99% of UVB, 60% of UVA, and 97% of visible light. ANSI categorizes these glasses as “special purpose.”

Don't be fooled. Wearing sunglasses with darker lenses doesn't mean greater protection from UV radiation than wearing ones with a lighter lens. Look for the ANSI label; even inexpensive sunglasses can be effective.

There is some evidence that blue light (UVA) from the sun may contribute to the development of age-related macular degeneration. Lenses with a red, amber, or orange tint may provide better protection against this light. You may find less distortion, however, with gray or green lenses.

If you aren’t sure what kind of sunglasses to buy or think you may be at high risk for eye disease, consult an eye care professional.

To learn about conditions that can affect the eye now and in the future, order our special health report, The Aging Eye: Preventing and Treating Eye Disease.

http://www.health.harvard.edu/AE

Q: I’ve recently heard that being moderately overweight is actually healthier than being at (or under!) a normal weight. I don't understand. I thought extra pounds were a health risk.

A: You're not alone in your confusion. A paper published in April by researchers at the Centers for Disease Control and Prevention (CDC) is behind the reports you've heard. The researchers set out to determine the number of deaths that could be attributed to being obese, overweight, and underweight. Their conclusions are controversial, and many physicians and researchers disagree with them.

The researchers gathered information from a set of surveys (the National Health and Nutrition Examination surveys) conducted from 1971 to 1994. After crunching the numbers, the CDC team concluded that people who were obese (body mass index of 30 or higher) or underweight (body mass index below 18.5) were more likely to die than people at a “normal” weight. That part was not controversial. However, the CDC team also concluded that people who were overweight but not obese (body mass index of 25 to 29.9) were at lower risk than people of normal weight. (To determine your body mass index, see the chart below.) That part has been highly controversial. The CDC speculated that advances in medical care have counteracted many of the health problems associated with being heavy, leading to weakened associations between obesity and mortality.

But the analysis has several problems. First, it included people with pre-existing illnesses, who are likely to have lost weight due to underlying disease — and more likely to die, thus inflating death rates among those at lower weights. This is a particular problem among the elderly. People tend to lose weight in their 70’s and 80’s due to underlying illness as well as loss of muscle mass. So being underweight is probably not the cause of death in these cases. It’s also extremely important to control carefully for cigarette smoking, which is more common among the lean. In a June 2, 2005 statement, the CDC acknowledged that obesity and overweight are genuine health threats, and more research is needed to determine the best way to measure how obesity affects death rates.

On the other hand, studies that effectively took into account smoking and pre-existing illnesses have found being overweight boosts mortality rates. Moreover, this research shows that being overweight increases your risk for diabetes, high blood pressure, heart disease, stroke, osteoarthritis, gallstones, many cancers, sleep apnea, and even asthma. And if the thought of these illnesses cutting your life short isn't compelling enough, just think about how they can affect the quality of your life.

Despite the clear health benefits, keeping our waistlines in check can be tough. Watch caloric intake and make sure that the calories you do eat are healthy ones — from fruits, vegetables, whole grains, and healthy fats (monounsaturated and polyunsaturated fats rather than saturated or trans fats). Regular exercise is good for mind and body; it not only can help control weight but directly reduces the risk for many diseases including heart disease, diabetes, and some cancers.

—JoAnn Manson, M.D., Dr.P.H.
Professor of Medicine, Harvard Medical School
Advisory Board Member, Harvard Health Letter, Harvard Women's Health Watch