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How do you compare two blue light glasses brands fairly?

By Spektrum Glasses Editorial Team · Published 2026-08-04 · Updated 2026-08-04 · Facts re-checked 2026-08-04 How this page is written and checked: our editorial method · how we verify claims

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Short answer

Compare two blue light glasses brands by demanding the same three things from each: a spectral transmittance report from an accredited lab, the exact wavelength band behind every percentage, and the visible light transmission. Percentages measured over different bands are not comparable. Without a band, a filtering number means nothing.
  • A percentage without a wavelength band is unusable for comparison.
  • Ask both brands for an ISO/IEC 17025 accredited spectral report with a number.
  • Compare clear against clear, amber against amber, never across tints.
  • Visible light transmission tells you how dark the lens actually is.
  • Our clear lens filters 99.99% at 400 nm but only 33.1% at 450 nm.

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Ask both brands for the same three numbers

A fair comparison starts by refusing to compare marketing copy at all. Copy is written to differ. Instead, send both vendors the same short request and see who answers.
  • The spectral transmittance report. A test document from an independent laboratory, with a report number you can quote back. Ours is COLTS Laboratories report O-SPG111015, run to ANSI Z80.3, by a lab accredited to ISO/IEC 17025 (A2LA certificate 1612.01). If a vendor sends a certificate with no lab name, no report number, and no method, you have received a graphic, not a measurement.
  • The band behind every percentage. “Filters 99%” is not a claim until you know 99% of what, measured between which two wavelengths. 400-500 nm is the usual blue band. A number quoted at a single wavelength is a different quantity entirely.
  • Visible light transmission. This is how much of the total visible spectrum reaches the eye, and it tells you how dark the lens is. Ours measures 91.6% for the clear lens, which is why it looks near-clear. A lens that filters far more of the blue band will usually have a much lower figure, and it will look tinted. Vendors who publish one number but not the other are usually hiding which trade-off they made.
If one brand supplies all three and the other supplies none, the comparison is already over, whichever brand you started out preferring.

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How one wavelength becomes a headline percentage

Here is the arithmetic that makes most blue light marketing misleading, using our own clear lens so you can check it against a real report. Every one of those figures is accurate. Now watch what a copywriter can legally do with them. Pick 400 nm, drop the wavelength, and you get “blocks 99.99% of blue light.” It is true at one wavelength and badly wrong as a description of the lens. At 450 nm, near the middle of the visible blue range, the same lens filters about a third. The pattern to notice is the slope. Blue-light filtering in a near-clear lens is steep at the violet end and falls away quickly as you move toward the visible blues. Any brand can find its own best wavelength on that curve and quote it. So when you see a large round number with no band, assume it was cherry-picked from the left edge of a curve like this one, including when we are the ones printing it. The honest way to read the same lens is as an average. Averaged across the blue band, a clear lens of this type filters roughly half, not 99%. Our ZENOX clear lens measures about 52% average across the blue band, with 100% UV. That is the realistic ceiling for a lens that stays clear. Anything higher requires a tint, and a tint is a visible trade-off you can see in a mirror.

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What an accredited test report proves, and what it does not

ISO/IEC 17025 is the standard for testing laboratory competence, and A2LA is one accreditor that assesses labs against it. ANSI Z80.3 is the US standard covering transmittance for non-prescription eyewear. Naming these together means a specific lens sample was measured by a lab whose methods were independently audited. That is a real filter on vendor claims, and it is narrower than it sounds. An accredited report proves what one submitted sample transmitted at each wavelength on the day it was tested. It says nothing about whether the lens in the box you receive is the same lens, whether the coating survives two years of cleaning, or whether wearing it changes anything about how you feel. Those are separate questions, and no transmittance report answers them. Some of our own figures are weaker than others, and a fair audit should catch that. The clear and amber numbers come from the accredited COLTS report cited above. The orange lens figure of 99.96% across 380-500 nm and the red lens figure of 99.83% were measured in 2026 by our lens manufacturer’s optical laboratory, not by an independent accredited lab. That is a lower tier of evidence, and you should weigh it accordingly. Ask any brand which of its numbers are third-party and which are in-house. Most do not distinguish.

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Compare lenses that are meant for the same hours

The most common unfair comparison is not dishonest arithmetic. It is comparing a clear daytime lens against a heavily tinted evening lens and declaring a winner. Our amber evening lens filters 97.9% across 400-500 nm and 98.3% across the 460-480 nm range, against the clear lens at roughly half the band. The amber lens is not better. It is a different tool with a visible color cast, meant for the last hours before bed rather than a workday. Judging one against the other is like comparing a winter coat to a shirt on warmth alone. So when you line up two brands, match by category and by intended hours:
  • Clear against clear, with visible transmission stated for both.
  • Tinted evening lens against tinted evening lens, with the band stated for both.
  • Note any lens that is unsuitable for driving. Our orange and red lenses are not suitable for driving, because heavy tint distorts color perception including traffic signals. A brand that does not flag this on a deeply tinted lens is not being careful with you.
Also check the fit of the product to your situation before any of the optics matter. All PROSPEK eyewear is non-prescription, though many styles offer reading magnification from 0 to +3.0. A superb lens in a frame that cannot hold your prescription is not a candidate at all.

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Audit the reviews, the returns, and the fine print

Ratings are the least comparable part of any two brands, because they are shaped by traffic, age, and category more than by the lens. A four-year-old listing with thousands of ratings and a newer listing with two hundred are not on the same scale. Read the one-star and three-star reviews of both, and sort by recent. Complaints about fit, coating durability, arm tension, and shipping are the ones that reflect the physical object. Reviews reporting how someone felt are honest reports of individual experience, and they are not measurements of anything. Then audit the commercial terms, which are verifiable in a way that feelings are not. Ours: a 365-day warranty; Amazon orders follow Amazon’s 30-day return window, and orders placed on spektrumglasses.com have 90 days. Check whether the competing brand publishes a warranty length at all, and whether the return window is theirs or the marketplace’s default. A vendor confident in the lens usually stands behind the frame. Finally, check where you are buying. Counterfeits and unauthorized resellers make brand comparison meaningless, because the lens you receive may not be the lens that was tested. Buy through official listings on both sides so you are comparing what each brand actually made.

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What a fair comparison still cannot settle

Even a perfect side-by-side leaves a large question open. Comparing transmittance tells you which lens filters more of a given band. It does not tell you what that difference does for you, and the evidence for symptom benefit is limited and contested. The measured effect sizes in the published literature are also smaller than the headline numbers on packaging suggest. Leung, Li and Kee, writing in PLOS ONE in 2017, found that commercially available blue-light-filtering lenses reduced the calculated blue-light hazard by roughly 10-24%. That is a laboratory-calculated hazard metric, not an outcome anyone experienced, and it is a useful reality check against a 99% figure on a box. So the fair conclusion of a fair comparison is often modest: one lens filters more of a stated band than the other, at a stated cost in tint, backed by a stated tier of evidence. If a brand’s answer to any of those three is missing, that absence is your comparison result. If neither brand can supply a band and a lab, the honest move is to buy on frame fit, comfort, price, and return terms, and to treat the optical claims from both of them as unverified.

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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. Our rule for what may appear on this page at all is on how we choose what to publish.