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# Does a thicker lens filter more blue light?
> No. How much blue light a lens filters is set by its tint and coating, not by how thick the lens is. Our clear day lens filters 99.99% of light at 400 nm b
# Does a thicker lens filter more blue light?
**By [Spektrum Glasses Editorial Team](https://kb.spektrumglasses.com/how-we-choose)** · Published 2026-08-30 · 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
No. How much blue light a lens filters is set by its tint and coating, not by how thick the lens is. Our clear day lens filters 99.99% of light at 400 nm but only 33.1% at 450 nm (COLTS report O-SPG111015) - a difference driven by wavelength and coating chemistry, not by slab thickness.
* Blue-light filtering comes from a lens's tint/coating, not its physical thickness.
* Our clear day lens filters 99.99% at 400 nm but only 33.1% at 450 nm.
* Reading power changes lens curvature, not the coating, so filtering doesn't change with diopter.
* A tinted lens filters far more of the 400-500 nm band than a clear lens of similar thickness.
* Two similarly thin clear lenses can filter very different amounts, proving tint drives the number.
## Thickness sets focusing power, not filtering
A lens gets thicker or thinner mainly because of the curvature needed to bend light to the correct focal point, and because of the material's refractive index. A stronger reading power needs more curvature, which is why a +3.00 lens is generally thicker through the center than a +0.50 lens of the same design. None of that curvature has anything to do with how much blue light the lens filters.
On our reading styles, the reading power sits in the same coated optical lens used on the plano (non-magnifying) version of the same frame. The coating that does the filtering is applied the same way across the whole strength range, from +0.50 to +3.00. So a stronger lens in one of our families is not a "stronger blue-light lens" — it is the identical coating on a more curved piece of plastic.
## What actually filters blue light
Filtering happens because a dye in the lens material and/or a coating on its surface absorbs or reflects light at specific wavelengths. That absorption is wavelength-dependent, which is exactly why a single percentage without a wavelength band is meaningless — a lens can filter almost all of the light at one wavelength and a small fraction of it a few nanometers away.
That wavelength dependence is also why blue-light-filtering lenses differ so much from each other in practice. A 2017 study in PLOS ONE (Leung, Li & Kee) found that commercially available blue-light-filtering lenses reduced the calculated blue-light hazard by roughly 10-24% — a wide range driven by differences in filter design between products, not by how thick any individual lens was.
## Our own measurements make the point
Our clear day lens was measured by COLTS Laboratories (A2LA-accredited to ISO/IEC 17025, spectral transmittance per ANSI Z80.3, report O-SPG111015) at four points in the near-UV to blue range:
| Wavelength | Filtered |
| ---------- | -------- |
| 400 nm | 99.99% |
| 410 nm | 95.1% |
| 420 nm | 63.0% |
| 450 nm | 33.1% |
Visible (photopic) transmission on that same lens is 91.6%, which is why it reads as near-clear rather than tinted. The same report's clear-lens group also passes ANSI Z80.3 transmittance and chromaticity testing on all samples — a standard that governs how a lens transmits light and holds color, not how accurately a reading power is ground.
For contrast, our ZENOX clear lens filters about 52% averaged across the whole 400-500 nm blue band, while also filtering 100% of UV. Both lenses are clear and both fall in the same thin, ophthalmic-lens thickness range — the different blue-band numbers come from how each lens's filtering layer is formulated, not from one being thicker than the other.
## Tint, not thickness, is what moves the number
The clearest evidence that thickness isn't the variable is what happens when we add a tint. Our clear day lens filters 33.1% at 450 nm. Our yellow evening lens — built for working late without going fully dark — filters 98% across the whole 400-500 nm blue band, 99.9% of high-energy visible light, and 98.3% at the 460-480 nm band associated with melatonin suppression, at roughly 65% visible transmission.
Our orange and red lenses go further still: orange filters 99.96% across 380-500 nm and red filters 99.83% across the same range, both measured in 2026 by our lens manufacturer's optical laboratory. Orange actually filters slightly more of the blue band than red does — red's real differentiator is that it also holds back green light out to 560 nm, which orange does not. Neither orange nor red is suitable for driving.
All of these lenses are produced in comparable ophthalmic thicknesses. The gap between 33.1% and 99.96% at overlapping wavelengths is a tint and coating story, not a thickness story.
## How to read a thickness or blue-light claim
If a lens is marketed as filtering more blue light because it is thicker, ask two questions: what wavelength band was measured, and was the comparison made against a lens with the same tint or a different one. A meaningful comparison holds the tint constant and changes only the coating or dye formulation — never the slab thickness alone.
For our own line, the honest summary is simple: pick a lens color for the time of day you'll wear it (clear for daytime, yellow for evening, orange or red for pre-sleep and overnight), and pick a reading power for how you see, independent of which one filters more blue light. The two decisions do not move together.
## 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.