The SPF factor in sunglasses
In today's materialistic world, we seem to think that everything is worn just for the sake of vanity, and sunglasses are no exception to this. The sunglass industry is a huge industry with products ranging from the cheap road-side junk to expensive, diamond studded items of luxury manufactured by brands such as Dolce and Gabbana and Chopard. In all this glitz and glamour, we must not forget that sunglasses do serve an actual purpose they protect our eyes from harmful UV rays of the sun. Ultra violent rays emitted from the sun can play a role in the development of cataracts and macular degeneration. In order to protect your eyes from the sun's harmful rays, be sure to wear sunglasses if you are going outside, especially during the summer when UV rays are twice as strong. Also, when participating in winter snow related sports, especially on high altitudes, ensure you bring a pair of sunglasses. And do not even think of going to the beach or any other such water body without eye protection. With all these varieties of sunglasses in the market, how do you decide on your pair? The next time you go sunglass shopping, look for the following things:- A high amount of UV absorption (99 or 100%): All sunglass lenses absorb some amount of UV light, but UV absorption can be improved by adding chemicals to the lens material during manufacturing or by applying special lens coatings. If the label says"UV absorption up to 400nm", it means 100% absorption.
- Impact resistant: When investing in a good pair of sunglasses, you want to ensure that it will last you a while and be worth your money. Although no pair of sunglass lenses is "unbreakable", it is fair to say that some lenses are stronger than others. Polycarbonate plastic lenses tend to fair better when hit by a ball or stone, but these also scratch easier. If you are going to purchase plastic lenses, look for scratch resistance as well.
- Polarization: Polarized lenses eliminate the entire reflected glare that bounces off smooth surfaces like pavement or water. Although this has nothing to do with the amount of UV absorption, they can be particularly useful for tasks such as driving and fishing.
- Lens darkness: Lens darkness usually corresponds directly with the effectiveness of UV blocking. Medium coloured lenses tend to do well for day-to-day needs, but some people need a darker lens. A new type of lens these days is photochromic lens. A photochromic glass lens is one that adjusts to the weather conditions outside. It automatically darkens in bright sunlight, and then lightens up when the sun rays get weaker. Darkening is relatively quick, taking place in approximately half a minute, but lightening takes a little longer, approximately five minutes.
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