"Blue-blocking"
Whether blue light is harmful to the eye is still controversial. Lenses that block all blue
light are usually amber and make your surroundings look yellow or orange. The tint
supposedly makes distant objects appear more distinct, especially in snow or haze. For
this reason, amber sunglasses are popular among skiers, hunters, boaters and pilots.

"Polarized"
Polarized lenses cut reflected glare - sunlight that bounces off smooth surfaces like
pavement or water. They can be particularly useful for driving and fishing. Polarization
has nothing to do with UV light absorption, but many polarized lenses are now combined
with a UV-blocking substance. These lenses are very soothing for eyes that are sensitive
to glare, and are highly recommended.

"Mirror-coated"
Mirror finishes are thin layers of various metallic coatings on an ordinary lens. Although
they do reduce the amount of visible light entering your eyes, do not assume they will
fully protect you against UV radiation.

"Wraparound"
Wraparound glasses are shaped to keep light from shining around the frames and into
your eyes. Studies have shown that enough UV rays enter around ordinary eyeglass
frames to reduce the benefits of protective lenses. Large-framed wraparound sunglasses
can protect your eyes from all angles.

"Gradient"
Gradient lenses are permanently shaded from top to bottom or from top and bottom
toward the middle. Single-gradient lenses (dark on top and lighter on the bottom) can cut
glare from the sky but allow you to see clearly below. They are useful for driving because
they don't dim your view of the dashboard. But they're not as good on snow or at the
beach, especially if they're clear on the bottom. Double-gradient lenses (dark on top and
bottom and lighter in the middle) may be better for sports where light reflects up off the
water or snow, such as sailing or skiing. Double-gradient lenses are not recommended for
driving, because they make the dashboard appear dim.