There are many lens types and coatings on the market today. Lenses have been made for many hundreds/thousands of years. Modern R&D has led to some new lens materials that can make a much thinner lens, or a much lighter lens than lenses of the past. Crown Glass and CR39 are the basic lens materials that have been around for generations. They both give very clear vision but both suffer from being thick, heavy and somewhat easily broken. Other lens types have been developed that are lighter, more impact resistant and can be made thinner as well. Polycarbonate is the most widely used lens type now, due to it’s impact resistance and it is lighter and thinner than either glass or CR39. However, polycarbonate isn’t always the best lens option.
Trivex is a newer material that is the lightest material available for glasses today. It is a perfect match for drilled rimless frames (like our Silhouettes) because it holds up the very best to the drilled holes and won’t crack or split. It is also very light, matching the benefits of a rimless, frame which frames are usually chosen due to their very light feel. Trivex also has clearer optics than polycarbonate; it distorts vision less than polycarbonate does. Trivex is almost as tough as polycarbonate for impact resistance as well. In fact, it is the second best material for safety reasons. As a result, your glasses can be very light, very clear and very tough.
Hi-index materials are made of materials that bend light better than crown glass or CR39. This means that they can give you the same level of correction as the other lenses while still being much thinner. For those with high prescriptions (those over 4.00DS usually benefit from these) these materials can sometimes make the difference of being able to close the temples on your glasses, to fit in a case or your pocket, or not.