Materials glossary / Lens material
CR-39 (plastic) lens
On the label: CR-39 · Lens material
What it is
The standard plastic lens since the 1940s: clear, light, cheap, better optics than polycarbonate and easier to scratch. Blocks most UVB but needs a UV coating or additive to reach UV400.
Lens materials: What a lens is made of decides its weight, clarity, impact resistance and how it takes a coating; UV blocking is a property of the material and its additives, not the tint.
In the research
27 PubMed papers mention it with jewelry, allergy, eyewear or UV; the three most recent:
- Polymeric Materials for Ophthalmic Lenses: A Systematic Review on Structure, Properties, Manufacturing and Sustainability · Molecules (Basel, Switzerland), 2026
- Meta-Analysis of Materials and Treatments Used in Ophthalmic Lenses: Implications for Lens Characteristics · Materials (Basel, Switzerland), 2024
- PC12 differentiation to neuron cells activated by a low-level laser at 660 nm on UV pre-treated CR-39 scaffolds with parallel microchannels · Biomedical optics express, 2024
A paper is a paper, not a verdict: titles are listed so you can read them, and a study on one fabric or one filter says little about the piece in your hand.
Other lens materials
Clasp & Lens describes materials from the public record and does not appraise, grade or test pieces; what a listing states is the supplier's statement. If a piece causes a rash, take it off; a reaction that spreads or blisters is a doctor's question, and sunglasses are no substitute for impact-rated eye protection where that is required.