Q. Do cheapo kids' sunglasses offer adequate protection?

A. Many do. The knockoffs that cost a couple of dollars can be just as effective as pricey shades. But to make sure lenses shield eyes from ultraviolet rays—associated with cataracts and retinal disease—check the label. (The color or darkness of lenses tells you nothing about UV protection.) Look for glasses that block 98 to 100 percent of UVA and UVB rays (or "have UV absorption of up to 400 nanometers"). A snug fit is also key. Ophthalmologists like wraparound designs because they keep sun from creeping in on the sides. Beyond that, leave the choice to your child. He'll be more likely to hold onto the glasses—and wear them—if he picks his own cover. —Jane Margolies