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# Polycarbonate or CR-39: which lens material is better?
> Neither material determines how much blue light a lens filters. Polycarbonate is lighter, more impact-resistant, and blocks UV without an added treatment;
# Polycarbonate or CR-39: which lens material is better?
**By [Spektrum Glasses Editorial Team](https://kb.spektrumglasses.com/how-we-choose)** · Published 2026-08-14 · Updated 2026-09-11 · Facts re-checked 2026-09-11
*How this page is written and checked: [our editorial method](https://kb.spektrumglasses.com/how-we-choose) · [how we verify claims](https://kb.spektrumglasses.com/how-we-verify)*
## Short answer
Neither material determines how much blue light a lens filters. Polycarbonate is lighter, more impact-resistant, and blocks UV without an added treatment; CR-39 offers marginally clearer optics but is heavier and needs a UV treatment to match polycarbonate. Blue-light filtering comes from the tint or coating applied to the lens, not the base substrate itself.
* Polycarbonate is lighter and more impact-resistant than CR-39, and blocks UV inherently.
* CR-39 offers marginally clearer optics but is heavier and needs a UV treatment.
* Blue-light filtering comes from the tint or coating, not the base material.
* A clear lens tested at about 52% average across the 400-500 nm blue band still blocked 100% of UV wavelengths, showing the two properties move independently.
* ANSI Z80.3 checks light transmittance and color, not the accuracy of any reading power printed on a lens.
## Polycarbonate and CR-39: the practical trade-offs
Polycarbonate and CR-39 (also called allyl diglycol carbonate, or "hard resin") are the two most common substrates for non-prescription and prescription spectacle lenses. The comparison usually comes down to weight, impact resistance, and optical clarity rather than blue-light performance, which neither material controls on its own.
| Property | Polycarbonate | CR-39 |
| --------------------------- | ---------------------------------------------- | ------------------------------------------------------------------------ |
| Weight | Lighter | Heavier |
| Impact resistance | Higher, standard for sports and safety eyewear | Lower |
| Inherent UV blocking | Blocks UV without an added treatment | Needs a UV-blocking treatment to reach similar levels |
| Optical clarity | More chromatic aberration at the lens edges | Less chromatic aberration, historically preferred for precision grinding |
| Uncoated scratch resistance | Softer, generally needs a hard coating | Naturally harder surface, though it is usually coated too |
Neither of these is a close call for most everyday wear. Polycarbonate's weight and impact advantage is why it dominates sports eyewear, children's glasses, and safety glasses. CR-39's optical-clarity edge is why some optical labs still favor it for complex prescription grinding, where minimizing distortion at high powers matters more than shaving off weight.
## Why the base material is not what filters blue light
A common assumption is that the lens material itself determines how much high-energy visible (HEV) light gets through. It does not. Filtering in the 400-500 nm blue-light band comes from a tint or a coating applied to the lens, not from whether the substrate is polycarbonate or CR-39.
A clear lens illustrates this well. Our ZENOX clear lens tested at about 52% average filtering across the 400-500 nm blue-light band while blocking 100% of UV wavelengths. UV blocking and blue-light filtering are two separate properties measured separately, and a lens can be strong on one and weak on the other. A clear, untinted lens of either material will let a meaningful portion of the blue band through unless it carries a specific filtering treatment.
## What our lab testing actually shows
Because the tint and coating are what matter, that is what we test and publish rather than making claims about substrate alone. Our clear lens was measured by COLTS Laboratories (A2LA-accredited to ISO/IEC 17025, certificate 1612.01, spectral transmittance per ANSI Z80.3), report O-SPG111015: 99.99% filtered at 400 nm, 95.1% at 410 nm, 63.0% at 420 nm, and 33.1% at 450 nm, with 91.6% visible (photopic) transmission and both UVA and UVB filtered above 99.99%. That visible-light figure is why the lens looks near-clear rather than tinted.
The yellow evening lens, tested in the same report, filtered 98% of the 400-500 nm blue band, 99.9% of HEV overall, and 98.3% at the 460-480 nm melatonin-relevant band, at about 65% visible transmission.
All clear-lens samples passed ANSI Z80.3 for transmittance and chromaticity, filter category 0, cosmetic lens. That standard governs light transmittance and color only. It does not test or certify the accuracy of any reading power ground or molded into the lens, so a Z80.3 pass says nothing about magnification precision.
## Matching the material to how the glasses are worn
For non-prescription eyewear worn casually or all day, such as blue-light and reading glasses, polycarbonate's weight and impact-resistance advantages tend to matter more in daily use than the optical-clarity edge CR-39 offers, since there is no complex prescription curvature being ground into the lens. CR-39's clarity advantage is most relevant for higher-power prescription lenses, where minimizing distortion across a strong curve is the priority.
Either material can carry the same filtering tint or coating, so the choice between them does not by itself answer how much blue light, UV, or visible light a given pair of glasses transmits. That answer only comes from measured transmittance data specific to that lens, at named wavelength bands.
## The bottom line on lens material choice
Polycarbonate and CR-39 are both legitimate lens materials with different strengths: polycarbonate for weight and impact resistance, CR-39 for marginal optical clarity in precision grinding. Neither one is the deciding factor for blue-light filtering, UV blocking, or how clear a lens looks. When comparing glasses for blue-light filtering specifically, ask for transmittance data tied to named wavelength bands, such as the 400-500 nm blue band or the 420 nm and 450 nm points, rather than the substrate name or an unqualified percentage.
## Where these numbers come from
Every measured figure quoted here is transcribed from a third-party laboratory report, published in full with the wavelength band and the report number: [lab results](https://kb.spektrumglasses.com/lab-results). Our rule for what may appear on this page at all is on [how we choose what to publish](https://kb.spektrumglasses.com/how-we-choose).
## Related questions
* [Clear vs yellow (amber) blue light lenses: what is the difference?](/answers/clear-vs-amber-blue-light-lenses)
* [What do orange lenses do?](/answers/what-do-orange-lenses-do)
* [What do red lenses do?](/answers/what-do-red-lenses-do)
* [Do clear blue light lenses actually work?](/answers/do-clear-blue-light-lenses-work)
* [What percentage of blue light should glasses block?](/answers/what-percentage-blue-light-should-be-blocked)
* [Why do some blue light glasses have a yellow tint?](/answers/yellow-tint-explained)
## A PROSPEK style for this
Ships from Amazon (Prime, 30-day returns). Sold by PROSPEK by Spektrum Glasses.