The best lens color choices are gray, green, or brown. Blue blockers are sunglasses with amber lenses that block blue light. Because blue light scatters in the eye, these lenses may increase your contrast in certain situations, however research has not established their effectiveness. Sunglasses have other options available to fit your needs. Polarized lenses block reflected light from the surface of water and are good for boating or driving.
Photochromic lenses adjust their darkness when the intensity of UV light changes.
Wrap around frames provide added protection from the sun. These should still be worn with sunglasses outside to provide additional protection. When buying sunglasses, don't be fooled by misleading labels. Price is generally not a reliable indicator of the lens quality or UV protection so should not be used in determining UV safety.