PLASTIC, POLYCARBONATE, TRIVEX: CHOOSING THE RIGHT LENS
Part 2 - In this particular case, our patient had a plastic lens because she chose not to get a reflection-free surface and wanted to save some money. Reflection-free surfaces greatly enhance the clarity of the optics with polycarbonate. We don’t recommend any polycarbonate lenses that do not have a scratch-resistant surface and a reflection-free surface. Polycarbonate is a very soft material. Though the optics have improved, we want you to see your best and don’t want you to have to hassle with unnecessary scratches. We do use polycarbonate (and/or Trivex) universally for children and those who need safety glasses, are involved in sports, or need a slightly thinner lens.
In this particular patient’s case, that was not the issue and so it is likely we chose plastic because it was economical and light, durable, and worked well with her frame. And, she was not in a high risk job needing impact-resistant lenses. In reality, I have only rarely in my 25 years as an eye doctor seen a patient where a plastic lens shattered. This can only happen in extreme situations. Lenses of all materials are required to go through drop-ball safety testing as required by the Occupational Safety and Health Administration (OSHA) before being released for prescription filling.
Posted on 03/21/2014 1:01 PM by Dr. Susan Kegarise
PLASTIC, POLYCARBONATE, TRIVEX WHAT'S THE DIFFERENCE?
We recently had a patient who filled her prescription in our optical with new frames and lenses. Later, she was out shopping and stopped by another eye doctor’s office. When she did, she talked to their optician who looked at her frames and lenses and said something to the tune of “I can’t believe that they filled your prescription with something other than polycarbonate. Your lenses could shatter.” This inaccurate comment made by a well meaning, yet less informed, optician stimulated me to write and clarify the unique differences in the lens materials that we offer.
In the beginning (well, a long time ago) most lenses for vision were made with glass, henceforth, “glasses.” Then, along came a revolutionary product called plastic. Or, what we commonly call in the business, CR-39 which was lighter, more shatter-resistant, but scratched easily. Because of the superiority of that product, people began to prefer plastic lenses over glass. Then, advances in polymer technology created new plastic lens products. The first was polycarbonate or “bullet-proof plastic.” The impact-resistance of polycarbonate was far superior and therefore all safety glasses started being made in polycarbonate. As you may remember from the past however, older polycarbonate lenses did not provide the clarity that a typical plastic or glass lens would because polycarb lenses do not transmit light as clearly. Following polycarbonate, “higher index” plastic lenses were developed which allowed us to make lenses thinner and lighter especially for high prescriptions. “Trivex” is the most recent advancement in polymer technology. It provides nearly the impact resistance of polycarbonate but in a clearer, more visually effective lens. In the near future, we will have even more impact-resistant and clearer lenses made with Biofilm, Nano technology and other scientific advancements.
Posted on 03/06/2014 2:09 PM by Dr. Susan Kegarise