There are many types of sunglasses out there, and trying to choose the type best for you can be very difficult. Many sunglasses make claims about being best for protecting against ultraviolet light, or other types of radiation from the sun. Knowing which protections work and which do not will make a big difference in your next sunglasses purchase. Read on to learn about the types of sunglasses that you should be looking for.
UV blocking is the number one feature to look for in sunglasses. Ultraviolet light is an invisible form of light emitted by the sun, so blocking it will not affect your ability to see at all, but it can be harmful if not blocked. Ultraviolet radiation is responsible for a number of eye disorders, including cataracts as well as cancer and other eye growths. Lens coatings rated to block 99 to 100 percent of radiation are essential for protecting your eyes. Sometimes, sunglasses will say “UV absorption up to 400nm” on the label, which means that 100% of all UV rays are blocked.
Ground and polished lenses are another key feature of quality sunglasses. Some nonprescription lenses are of a low quality, causing image distortion that is hard to notice but will cause eye strain and headaches. Ground and polished lenses are smoothed out to prevent this effect, ensuring that light is not bent while moving through the lenses. The easiest way to check for deformities in nonprescription lenses is to find a checkered or rectangular tile pattern, like a chess board or a tile floor. Hold the glasses away from your eyes and move them up and down, and side to side. If the straight lines you are looking at through the glasses wiggle or deform, the lenses are not ground and polished.
Lenses that are resistant to damage are also an important sunglasses feature. Impact resistant lenses are most important; some lenses are made of brittle glass that can shatter and get in your eyes if hit by a flying stone, a ball, or other impact. Obviously no material is completely unbreakable, but sunglasses made of plastic or polycarbonate are much more impact resistant, and thus safer. Polycarbonate lenses are the strongest against breaks, but the downside is that they scratch easily. For sports or other activities in which impacts are a higher than usual risk, polycarbonate lenses with scratch resistant coating are the best choice. For day to day wear, high quality plastic lenses are more practical and affordable.
There are many features to consider when buying sunglasses to ensure that they will protect your eyes. UV protection is the number one concern, especially since sunglasses allow you to look into sunlight that otherwise would cause you to flinch away. Ground and polished lenses make a big difference in reducing eye strain by not bending the light that passes through them. Finally, impact and scratch resistant lenses are important for day to day wear, and especially for sports and other physical activities.