Sponsored by PPG INDUSTRIES, Inc.
By Linda Conlin
In Lewis Carroll’s Alice in Wonderland, the Mock Turtle sings longingly of “Beautiful Soup.” There’s another “beautiful soup” you should know about. It’s the chemical solution used to make ophthalmic lenses. Every lens material has been developed through extensive research and testing, multiple processes and stages, including FDA approval as a Class 1 Medical Device. Exact lens material formulas are proprietary, but let’s look at the main ideas behind developing Tribrid lenses.
Tribrid lenses are produced using a unique hybrid material technology that is the combination of PPG TRIVEX® lens material and traditional high-index technology. High-index lenses are made by polymerizing specific monomers. In plainer terms, a monomer is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization. Based on the specific monomers, the resultant “soup” will yield a lens that has a high refractive index, which in turn will result in a thinner eyeglass lens. Next, the monomer mixture is put into a mold which is placed in an oven to undergo a heat cycle, turning it into a lens blank. The lens is then inspected and sent to a lab for final processing.
Trivex is manufactured through a similar process, but the ingredients in the soup are different. Trivex material is a urethane-based pre-polymer that PPG developed and refined for use as an ophthalmic lens material. A pre-polymer is a substance that is in the intermediate stage of polymerization. PPG enhanced the base polyurethane molecule by enriching it with additional nitrogen. The result is a lens material that is not only optically superior but also exceptionally strong and ultra-lightweight.
Tribrid lens material was introduced in 2012 as a high index extension of the Trivex family to address patient needs for thinner lenses. It combines the best lens properties of high-index and Trivex to provide patients with enhanced all-around performance for stronger prescription requirements. The material offers excellent optical quality (ABBE 41), lightweight (1.23 g/cm specific gravity), thinness (1.60 index of refraction) and strength (up to 5X more impact resistant than other high index lens materials). In fact, the lenses can withstand more than 160 times the energy of the U.S. Food and Drug Administration drop ball test, making it the perfect lens material for Rxs of +/- 3D to +/- 7D.
The lenses feature precision optics to optimize stronger prescriptions for clear vision at all times and provide a stronger lens for enhanced safety, durability and confidence in every lens. The stronger, more durable lenses are perfect for children, active adults, seniors and those with an eye toward fashion. They’re compatible with all frame styles and designs, including work and sport glasses, as well as with digital, free-form processing and anti-reflective coatings. What’s more, they feature 100 percent UVA/UVB protection in a clear lens without compromising clarity. The lightest high index material available, Tribrid provides all-day comfort and performance with the aesthetics and beauty of a thin lens.
Tribrid has benefits, not only for patients, but for labs too. The lenses process easily using standard high index processing—no special wheels or tooling are required. They are easy to edge, drill, groove and mount with fewer chip and crack defects on drilling and frame flex versus polycarbonate and other 1.60 and 1.67 lenses, based on COLTS lateral bridge stress frame test. Lenses can be backside spin coated and offer improved scratch resistance, along with excellent compatibility with AR coatings. Tribrid also has superior chemical resistance to cracking or crazing from common lab and household chemicals such as isopropyl alcohol, caustics and acetone.
Tribrid lenses offer more benefits and overall performance that are right for every patient. As with Trivex material, you can recommend Tribrid lenses with confidence knowing that this new and unique high index lens offers similar performance benefits to Trivex material with enhanced thinness and lightest weight. They don’t require special lab processing or handling. With every prescription, clear vision is always important, and with a high Abbe value, they’re perfect for your patients with stronger prescriptions and more demanding vision correction needs. Tribrid offers your high-prescription patients the best, from beautiful soup to nuts.
You can learn more about the material science of ophthalmic lens monomers or lens casting in the production of finished or semi-finished lens blanks with our CE, “The Mystery, the Magic & the Science behind the Ophthalmic Lens Blank” at 2020mag.com. This course is free, courtesy of an educational grant from PPG Industries.