When buying new glasses, consider how much protection you need against the sun. The American Optometric Association recommends wearing sunglasses with an SPF of at least 15 every day in direct sunlight.
Look for Frames with Protection Against UVA/UVB Rays.
If you're looking for sunglasses that offer protection against both UVA and UVB rays, choose lenses made of polycarbonate plastic. These lenses block out up to 99% of both types of ultraviolet light.