Lens Material Matters
As most of us know, it’s snow and ice season in Illinois. In our area, we have some wonderful, dedicated men and women who plow, doing their best to keep our roads clean and safe. Despite their best efforts, accidents still happen. While the majority of them are minor, there are always a few disastrous collisions around this time of year. For drivers who wear glasses, the material their spectacle lenses are made of can be the difference between safety and eye injuries. In this blog, we’re going to be looking at our favorite materials for protecting your eyes while driving.
Most people believe that the lenses in their glasses are made of glass. While glass lenses used to be the preferred material for eyeglasses, they are on the very bottom of that list today. Although the clarity and scratch resistance of glass is (almost) unmatched, the risks of using this particular medium for eyewear far outweighs the benefits. Since the invention of safer materials, glass lenses are all but extinct. We do not prescribe them in our optical for this reason.
Plastic lenses (also called CR-39) were the next to come onto the market. These lenses are relatively hard and offer better impact resistance than their glass counterparts. A hard coat can also be applied for even better scratch resistance. Plastic though, still isn’t rated for safety, and one swift hit will result in the lenses shattering.
Polycarbonate or Trivex lenses are the preferred lens material when impact resistance and safety trump all other aspects of the eyeglasses. These materials are lightweight and bend when force is applied to them. The ability to flex, rather than shatter, when hit is what makes polycarbonate and trivex so safe. Between the two, there are a few differences. Trivex is 10% lighter than polycarbonate, and is also 10% clearer. Since polycarbonate has a higher index of refraction, it is about 10% thinner. Because polycarbonate has been around longer, it has become the gold standard for safety lenses, as well as other applications including windshields and windows.
So how do we, as your optical professionals, decide when to use polycarbonate and trivex? We look at a number of things, such as prescription, lifestyle, age, and frame choice, to determine your need for this feature. Impact resistant lenses are always prescribed for children under 18. Eye injuries due to sports, play, or accidents are common among kids, so adding extra protection to a pair of glasses is a must. Adults who lead an active lifestyle, such as tradesman and hobbyists, can benefit from impact resistant materials as well. If you pick a frame that needs to be grooved at the bottom (a semi-rimless design) or one that needs to be drilled into (a completely rimless design) you’ll need an impact resistant lens for added durability and structure.
Unless you have a very high prescription, impact resistant lenses are never a hindrance. Your optician will explain all the benefits and differences between materials so that you can make an informed decision about which option will be best for you. An ounce of prevention is worth a pound of cure, and you’ll be happy you opted in for impact resistant lenses when disaster strikes.