Polycarbonate Lenses
Polycarbonate was developed in the 1970s for aerospace applications. It is used in helmet goggles for astronauts and windshields for the space shuttle. Polycarbonate was adapted for eyeglass lenses to meet the demand for lightweight, impact-resistant lenses.
Polycarbonate lenses have become the standard for safety glasses, sports goggles and children's eyewear. Polycarbonate lenses are also a good choice for rimless eyeglasses because they are less likely to break than regular plastic lenses. (Lenses for rimless eyeglasses are mounted to the frame components by drilling holes.)
Polycarbonate is a thermoplastic that began as a solid material in the form of small particles. In the process of manufacturing eyeglass lenses (called injection molding), the polycarbonate granules are heated until they melt. The liquid polycarbonate is then quickly injected into a lens mold, compressed under high pressure, and cooled to form the finished lens in a matter of minutes.
Trivex Lenses
Trivex is another lightweight, impact-resistant material for eyeglass lenses. Like polycarbonate, Trivex is a premium lens material for safety applications and children's eyewear.
Developed by PPG Industries in 2001, Trivex lenses are lightweight and offer greater impact resistance than ordinary plastic or glass lenses.
Trivex lenses are made from polyurethane monomers. They are produced using a slower cast molding process, similar to that used to manufacture regular plastic lenses. The liquid lens material is slowly baked until it solidifies. According to PPG, this gives Trivex lenses clearer optics than injection-molded polycarbonate lenses.
Polycarbonate Lenses vs. Trivex Lenses
Here's a brief comparison of polycarbonate lenses and Trivex lenses to help you decide which lens is best for you:
Thickness. Polycarbonate lenses are approximately 10% thinner than Trivex lenses.
Weight. Trivex lenses are approximately 10% lighter than polycarbonate lenses.
Optics - Center. Trivex lenses have less internal stress and produce a clearer central vision than polycarbonate lenses.
Optical - Peripheral: Trivex lenses have a higher Abbe value, producing clearer peripheral vision with less chromatic aberration than polycarbonate lenses.
Impact Resistance. Polycarbonate lenses and Trivex lenses have comparable impact resistance.
UV Protection. Both polycarbonate and Trivex lenses block 100% of the sun's UV rays without the need for special UV lens coatings.
Availability. Polycarbonate lenses are available in a wider range of lens designs (e.g., progressive and other multifocal lenses) than Trivex lenses. Color-changing lenses are available in both materials.
Cost. The cost of polycarbonate and Trivex lenses can vary greatly, but many opticians charge more for Trivex lenses than polycarbonate lenses.
Your professional optometrist can discuss the pros and cons of polycarbonate and Trivex lenses so you can decide which lens material is best for your needs and budget.
Scratch Protection
Polycarbonate and Trivex lenses are more impact resistant than regular glass and plastic lenses (including other high index lenses) because these lightweight lens materials are relatively “soft” - meaning they can absorb energy without causing the lens to breakage.
This flexibility also means that polycarbonate and Trivex lenses require scratch-resistant coatings to prevent surface scratches. Today's modern scratch-resistant coatings can make the surface of polycarbonate and Trivex lenses almost as hard as glass.
Most eye care professionals offer a lens warranty to protect your lenses from scratches for a specific period of normal use. Consult your optometrist for details.
Frames for Polycarbonate and Trivex Lenses
Polycarbonate and Trivex eyeglass lenses are only part of the solution when it comes to eye safety.
For optimal eye protection at work and during sports, make sure you also purchase high-quality safety frames or frames designed specifically for sports eyewear.
Ordinary spectacle frames are not suitable for use as safety glasses and usually do not provide the eye protection required for sports. Therefore, playing sports in frames that are not suitable for sports is dangerous and can lead to serious eye injuries if the frame breaks and the lenses fall out.
If you need safety glasses, consult an optometrist who can tell you which frames have a safety rating.
For children's eyewear, choose sturdy frames and lightweight polycarbonate or Trivex lenses. Even if your child doesn't play organized sports, choosing impact-resistant lenses and frames is an important step in protecting your child's eyes all day and maintaining good vision throughout their lives.
Thank you for reading.
