We are frequently asked what some of the terms used in sunglasses descriptions, so we put together some answers to the hopefully guide you in the right direction.
“Blocks 99% of ultraviolet rays”
You should always buy sunglasses with this feature. Both plastic and glass lenses absorb some UV light, but UV absorption can be improved by adding chemicals to the lens material during manufacturing or by applying special lens coatings. Shop for sunglasses that block 99 or 100% of all UV light. Some manufacturers’ labels say “UV absorption up to 400nm.” This is the same thing as 100% UV absorption.
“Blocks 90% of infrared rays”
Infrared wavelengths are invisible and produce heat. Sunlight has low levels of infrared rays, and the eye tolerates infrared well. Some sunglasses manufacturers make health claims for their products based on infrared protection, but research hasn’t shown a close connection between eye disease and infrared rays.
Lenses that block all blue light are usually amber and make your surroundings look yellow or orange. The tint 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 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 finishes are thin layers of various metallic coatings on an ordinary lens. Although they do reduce the amount of visible light entering your eyes, don’t assume they will fully protect you against UV radiation.
Wraparound glasses are shaped to keep light from shining in around the frames. Studies have shown that enough UV rays enter around ordinary eyeglass frames to reduce the benefits of protective lenses. Large-framed wraparound sunglasses help to protect your eyes from all angles.