What Is CR-39? The Lens Material Behind Clear, Durable Glasses
If you've shopped for glasses, you've probably seen "CR-39" listed as a lens option and wondered what it actually means. It's not a brand name or a marketing term — it's the material your lenses are made from, and it's one of the most trusted choices in eyewear today.
What CR-39 Actually Is
CR-39 stands for "Columbia Resin 39." It's a lightweight plastic polymer that was originally developed in the 1940s and has been the standard for optical lenses ever since. When opticians and lens labs talk about "standard plastic lenses," they're almost always talking about CR-39.
The name comes from its place in a research sequence — it was the 39th formula in a series of thermosetting plastics developed by the Columbia Resins project. It stuck around because it turned out to be exceptionally well-suited for optics.
Why CR-39 Is Still the Go-To Material
Decades after its invention, CR-39 remains a go-to lens material for a simple reason: it does the fundamentals extremely well.
- Excellent optical clarity. CR-39 has great light transmission, which means sharp, clear vision with minimal distortion.
- Lightweight comfort. It's noticeably lighter than glass, so glasses sit comfortably on your face for all-day wear.
- Scratch resistance. With a coating (which most CR-39 lenses come with), it holds up well to everyday handling.
- Impact resistance. It's far more shatter-resistant than glass, making it a safer everyday choice.
- Easy to tint and coat. CR-39 takes tints, anti-reflective coatings, and UV treatments well, which is part of why it's so versatile across prescriptions and styles.
This combination is exactly why CR-39 has remained a trusted, high-quality standard in the optical industry for over 80 years — it's not a stripped-down option, it's a proven one.
CR-39 vs. Other Lens Materials
You'll also see options like polycarbonate or high-index lenses. Here's how they compare:
- Polycarbonate (index 1.59) is even more impact-resistant and a common choice for kids' glasses, sports eyewear, or rimless frames — but it has slightly lower optical clarity than CR-39.
- High-index lenses (typically index 1.67 or 1.74) are thinner and lighter, which matters most for stronger prescriptions, but they typically cost more.
- CR-39 (index 1.49) strikes the balance most people are looking for: excellent clarity, solid durability, and reliable performance for the vast majority of prescriptions.
Is CR-39 Right for You?
For most single-vision and progressive prescriptions, CR-39 is a fantastic choice — which is exactly why it's the material we use in our $95 frames-and-lenses package at Peek. It delivers the clarity and durability you want in a pair of everyday glasses, without compromise.
When CR-39 Isn't the Best Fit
CR-39 is a great match for most prescriptions, but it does have limits worth knowing about. Because it's a standard-thickness material, CR-39 generally isn't recommended for prescriptions with a sphere (SPH) power stronger than +/-3.00 or a cylinder (CYL) power stronger than +/-2.00. At those higher powers, CR-39 lenses tend to become noticeably thicker and heavier — which can affect both comfort and appearance, especially at the lens edges.
If your prescription falls into this stronger range, a polycarbonate or high-index lens is usually the better choice. Higher index materials bend light more efficiently, allowing the lens to be made thinner and lighter even at higher powers, while still delivering clear, comfortable vision.
Ready to see clearly? Browse our frames and get started with a pair built on lenses that have stood the test of time.*
