Polycarbonate and Trivex Lenses

Polycarbonate lenses

When eye safety is a concern, polycarbonate or Trivex lenses usually are the best choice for your eyeglasses, sunglasses and sports eyewear.

Both polycarbonate lenses are thinner and lighter than regular plastic lenses. They also offer 100 percent protection from the sun’s harmful UV light and are up to 10 times more impact-resistant than plastic or glass lenses.

This combination of lightweight comfort, UV protection and impact resistance also makes these lenses an excellent choice for children’s glasses and safety glasses.

Polycarbonate was developed in the 1970s for aerospace applications, and is currently used for the helmet visors of astronauts and for space shuttle windshields. Eyeglass lenses made of polycarbonate were introduced in the early 1980s in response to a demand for lightweight, impact-resistant lenses.

Since then, polycarbonate lenses have become the standard for safety glasses, sports goggles and children’s eyewear. Because they are less likely to fracture than regular plastic lenses, polycarbonate lenses also are a good choice for rimless eyewear designs where the lenses are attached to the frame components with drill mountings.

Most other plastic lenses are made from a cast molding process, where a liquid plastic material is baked for long periods in lens forms, solidifying the liquid plastic to create a lens.

But polycarbonate is a thermoplastic that starts as a solid material in the form of small pellets. In a lens manufacturing process called injection molding, the pellets are heated until they melt. The liquid polycarbonate is then rapidly injected into lens molds, compressed under high pressure and cooled to form a finished lens product in a matter of minutes.

Best recommended for;

  • Children
  • Sports personnel
  • Those wants clear lenses without tint with UV protection
  • For high prescriptions both myopic as well as hyperopic
  • For rimless frames

Trivex lenses

When eye safety is a concern, polycarbonate or Trivex lenses usually are the best choice for your eyeglasses, sunglasses and sports eyewear.

Both polycarbonate lenses are thinner and lighter than regular plastic lenses. They also offer 100 percent protection from the sun’s harmful UV light and are up to 10 times more impact-resistant than plastic or glass lenses.

This combination of lightweight comfort, UV protection and impact resistance also makes these lenses an excellent choice for children’s glasses and safety glasses.

Despite its many advantages, polycarbonate isn’t the only lens material suitable for safety applications and children’s eyewear.

In 2001, PPG Industries (Pittsburgh, Penn.) introduced Trivex. Like polycarbonate lenses, lenses made of Trivex are thin, lightweight and much more impact-resistant than regular plastic or glass lenses.

Trivex lenses, however, are composed of a urethane-based monomer and are made from a cast molding process similar to how regular plastic lenses are made. This gives Trivex lenses the advantage of crisper optics than injection-molded polycarbonate lenses, according to PPG.

Best recommended for;

  • Children
  • Sports personnel
  • Those wants clear lenses without tint with UV protection
  • For high prescriptions both myopic as well as hyperopic
  • For rimless frames

Polycarbonate vs. Trivex Lenses: A Quick Comparison

Here is a brief comparison of polycarbonate and Trivex lenses to help you decide which lenses might be best for you:

  • Thickness: Polycarbonate has a higher index of refraction than Trivex (1.58 vs. 1.53), so polycarbonate lenses are about 10 percent thinner than Trivex lenses.
  • Weight: Trivex has a lower specific gravity than polycarbonate, making Trivex lenses about 10 percent lighter than polycarbonate lenses.
  • Optical Clarity (central): Trivex lenses have less internal stress and may produce sharper central vision than polycarbonate lenses.
  • Optical Clarity (peripheral): Trivex lenses have a higher Abbe value and may produce sharper peripheral vision with less chromatic aberration than polycarbonate lenses.
  • Impact Resistance: Polycarbonate and Trivex lenses have comparable impact resistance.
  • UV Protection: Polycarbonate and Trivex lenses both block 100 percent of the sun’s UV rays without the need for special UV-blocking lens coatings.
  • Availability: Polycarbonate lenses are available in a wider variety of lens designs (e.g., progressive and other multifocal) than Trivex lenses.
  • Cost: The cost of polycarbonate and Trivex lenses can vary considerably, but many optical stores charge more for Trivex lenses than polycarbonate lenses.

Your professional optician can discuss the pros and cons of polycarbonate and Trivex lenses so you can decide which lens material is the best choice for your needs and budget.

Scratch Protection

Polycarbonate and Trivex lenses are much more impact-resistant than regular glass and plastic lenses (including other high-index lenses) because these lightweight lens materials are relatively “soft” — which means they can absorb energy without lens fracturing.

This flexibility also means polycarbonate and Trivex lenses need a scratch-resistant coating to prevent surface scratches. Today’s modern scratch-resistant coatings can make the surface of polycarbonate and Trivex lenses nearly as hard as glass.

Most eye care professionals offer a lens warranty to protect your lenses against scratches for a specified period of normal use. Ask your optician for details.

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