> ## Documentation Index > Fetch the complete documentation index at: https://kb.spektrumglasses.com/llms.txt > Use this file to discover all available pages before exploring further. # How can you tell a real blue light coating from a marketing-only claim? > A real coating comes with a spectral test report that states a percentage tied to a specific wavelength band (for example, 95.1% at 410 nm) from an accredi # How can you tell a real blue light coating from a marketing-only claim? **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 A real coating comes with a spectral test report that states a percentage tied to a specific wavelength band (for example, 95.1% at 410 nm) from an accredited lab. A marketing-only claim states a single blanket percentage with no band, no lab name, and no accreditation standard behind it. * A percentage with no wavelength band attached (e.g. 400-500 nm) is not verifiable data. * Look for a named accredited lab and standard, such as ISO/IEC 17025 or ANSI Z80.3. * ANSI Z80.3 covers light transmittance and color, not reading-power accuracy. * A visibly clear lens cannot filter an entire blue-light band; heavier filtering needs a visible tint. * Published research on blue-light lenses is mixed and does not support broad symptom claims. ## A number without a wavelength band is not a fact Blue light sits in the 400-500 nm range of the visible spectrum, and no honest test reports a lens's performance across that whole range as one number. A lab measuring transmittance produces a curve across specific wavelengths, because filtering is rarely flat: a coating typically blocks far more of the high-energy light near 400-420 nm than it does light closer to 450-500 nm. When a listing or ad says a lens 'blocks 99% of blue light' with no band attached, there is no way to know what was actually measured, or whether anything was measured at all. It could be quoting the single highest point on a curve, a rounded-up average, or nothing tested. Our own clear lens, for example, is reported at 99.99% at 400 nm and 33.1% at 450 nm in the same lab report - two very different numbers from one lens, which is exactly why the band matters more than the headline percentage. ## What an accredited lab report actually contains A real spectral report names the testing lab, the accreditation body behind that lab, and the standard the test was run against - and a seller should be able to produce it on request. Ours, for example, comes from COLTS Laboratories, accredited to ISO/IEC 17025 by A2LA, tested for spectral transmittance under ANSI Z80.3. ANSI Z80.3 is worth understanding on its own terms: it is a transmittance and chromaticity standard for non-prescription sunglass and fashion eyewear, covering how much light passes through a lens and what color it appears, sample by sample. It says nothing about whether a printed reading power is accurate to that power. A lens can pass Z80.3 on transmittance and color and still have no standards testing behind its magnification. If a listing implies 'ANSI certified' covers the reading strength, that is the same dishonest pattern in a different form: a real standard applied to something it does not measure. ## Why a clear lens cannot block an entire band A lens that looks colorless and a lens that filters a large share of the 400-500 nm band are working against each other, because the wavelengths responsible for blue light are the same wavelengths the eye reads as color. Filtering more of the band without adding a visible tint runs into a physical ceiling. That ceiling shows up in test data. A near-clear coated lens can filter the highest-energy, near-violet edge of the range almost completely while transmission closer to 450-500 nm has to stay much higher to keep the lens looking clear - in our own clear lens that is 33.1% filtered at 450 nm against 91.6% overall visible-light transmission. A different clear lens in our product range filters roughly 52% of the blue band on average while passing all UV, which shows the same tradeoff on a different coating. A yellow lens can filter far more of the band - in our case 98% across 400-500 nm and 98.3% at the 460-480 nm range - but only by visibly changing what the wearer sees, which a genuinely clear lens cannot do. If a seller claims a clear lens filters a figure in that range, ask which wavelengths, and look at the lens. ## What the published research does and does not show Separate from whether a coating measures as claimed, the research on what filtering blue light does for a wearer is thin, and several recent studies are unfavorable to strong claims. A 2017 PLOS ONE study on commercially available blue-light-filtering lenses found they lowered a calculated blue-light hazard measure by roughly 10 to 24 percent - a measurable optical effect, not a symptom outcome. A November 2025 meta-analysis in Frontiers in Neurology, pooling three randomized controlled crossover trials with actigraphy-measured outcomes (n=49), found sleep onset latency, total sleep time, sleep efficiency, and wake-after-sleep-onset were all statistically non-significant between blue-blocking and control lenses; the authors describe current trial evidence as not supporting a significant effect, while leaving open the possibility of a small effect too small for existing trials to confirm. A January 2026 review in Therapeutic Advances in Ophthalmology similarly found minimal or no significant difference in contrast sensitivity, color discrimination, or task performance between blue-light-filtering and standard lenses, and describes the evidence on eye strain and circadian outcomes as still debated among researchers. None of this means a coating does nothing for any individual wearer - comfort is subjective and varies - but it does mean a seller citing unnamed 'studies' without a specific source is making a claim the current published evidence does not clearly support. ## A short checklist before you buy Use this before trusting a blue-light claim on any brand's listing: * Ask for the wavelength band behind any percentage. 'Blocks 99%' with no band attached is not a data point. * Ask for the lab name and the standard used. 'Lab tested' with no lab named is not verifiable. * Match the tint to the claim. A lens that looks completely clear cannot be filtering the same share of the band as a visibly tinted one. * Treat 'ANSI certified' claims about magnification with suspicion; ANSI Z80.3 covers light transmittance and color, not reading power. * Be skeptical of any promise of better night driving from a tinted lens. The UK College of Optometrists and US NHTSA guidance both advise against relying on tinted lenses for night driving, since they cut the light reaching the eye rather than adding any. A 1997 FTC enforcement action against a 'night driving safety' eyewear claim is on the public record and a reminder that this specific promise carries real regulatory risk for any brand that makes it. * If in doubt, buy from a seller with a real return policy, so a lens that does not perform as claimed is not a sunk cost. ## 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 * [How do you choose blue light glasses?](/answers/how-to-choose-blue-light-glasses) * [How much should blue light glasses cost?](/answers/how-much-should-blue-light-glasses-cost) * [Can you wear blue light glasses all day?](/answers/can-you-wear-blue-light-glasses-all-day) * [Can you wear blue light glasses over contact lenses?](/answers/blue-light-glasses-over-contacts) * [Can you wear blue light glasses over prescription glasses?](/answers/blue-light-glasses-over-prescription) * [Are clip-on blue light filters any good?](/answers/clip-on-blue-light-filters) ## A PROSPEK style for this Ships from Amazon (Prime, 30-day returns). Sold by PROSPEK by Spektrum Glasses.