Lens Materials: CR39 vs. Polycarbonate

Lens Materials

Which Lens Material Is Right For You?

Even with all the technological advances of the last millennia, good old- fashioned glass still can’t be beat when it comes to optical clarity and scratch resistance, which are two very practical traits when it comes to corrective lenses. This may explain why glass was the lens material of choice for the first 500 years that ophthalmic lenses were widely available. But for all their virtue, glass lenses do have some major drawbacks: they are extremely heavy, shatter easily (and dangerously) and provide little protection from the sun’s damaging UV rays.

 

Advances in Material Science

 

By the 1950s, research and development of plastics revolutionized almost every aspect of daily life, from clothing to cooking to construction. The wave of innovation swept through the eyewear industry and lens materials with the creation of CR-39. This plastic formulation offers the clarity and durability of glass while eliminating much of its fragility and weight. Economical, readily available CR-39 quickly became the standard lens material for all vision correction needs. In the 1980s, the next huge step in material science brought the optical industry polycarbonate lenses. This revolutionary material improved on the impact-resistance and weight of even CR-39, while also offering 100% UV protection.

 

Lens Materials Pros and Cons

 

These polycarbonate lenses are the strongest and lightest lenses available, so they are an excellent choice for young children or those involved in high-impact work or activities. But being lightweight and shatter-resistant comes with some trade-offs that make them less desirable for normal everyday wear. While a polycarbonate lens can take a bullet without shattering, they are extremely scratch-prone. And the material’s density, which allows the lenses to be so thin, also causes a high amount of visual distortion and blurriness known as chromatic aberration.

Thankfully, there are more options than ever available to patients looking for a cosmetically desirable, comfortable lens but who don’t want to sacrifice on clarity as required with polycarbonate. High-index plastics can approximate lightweight polycarbonate without as much distortion, and new digital surfacing techniques allow thinner lenses to maintain more of the desirable optical qualities of original CR-39. Our experienced opticians are highly trained to help you find the lens solution that best fits your vision needs and lifestyle.