> ## 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.

# What is ISO/IEC 17025 accreditation, and why does it matter for lens tests?

> ISO/IEC 17025 is the international standard for the technical competence of testing laboratories. An accredited lab has been audited by an accreditation bo

# What is ISO/IEC 17025 accreditation, and why does it matter for lens tests?

**By [Spektrum Glasses Editorial Team](https://kb.spektrumglasses.com/how-we-choose)** · Published 2026-08-04 · Updated 2026-08-04 · Facts re-checked 2026-08-04

*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

ISO/IEC 17025 is the international standard for the technical competence of testing laboratories. An accredited lab has been audited by an accreditation body such as A2LA against that standard for its methods, calibration, traceability, and uncertainty, and holds a numbered certificate. For lenses it matters because it makes a transmittance figure reproducible and traceable rather than a marketing number.

<Note>
  * ISO/IEC 17025 covers lab competence; ISO 9001 covers management systems, not test accuracy.
  * Accreditation is scoped to named methods, so check the method, not just the logo.
  * A percentage with no wavelength band is uninterpretable, accredited or not.
  * The same clear lens measures 99.99% at 400 nm and 33.1% at 450 nm.
  * An accredited report describes the sample tested, not every production lot.
</Note>

## What ISO/IEC 17025 accreditation actually means

ISO/IEC 17025 is the international standard for the competence of testing and calibration laboratories. A lab does not award it to itself. An accreditation body — A2LA is one of the recognized ones in the United States — sends technical assessors to audit the lab against the standard, then issues a numbered certificate that can be looked up in the accreditor's public directory.

The audit covers the things that decide whether a number is real: whether the test method is validated and correctly applied, whether the spectrophotometer and reference standards are calibrated with traceability to national standards, whether staff are demonstrably competent on that method, whether the lab states its measurement uncertainty, whether records let a third party reconstruct the test, and whether the lab performs acceptably in inter-laboratory comparisons.

Accreditation is also scoped. A lab is accredited for a defined list of methods, not for testing in general. A certificate that is real and current still tells you nothing if the test you care about sits outside the scope it covers.

## Accreditation, certification, and a factory test sheet are not the same thing

Three different documents get shown to buyers as if they were interchangeable, and they are not.

* **ISO/IEC 17025 accreditation** says a specific lab is technically competent to run specific tests. This is the one that makes a transmittance number defensible.
* **ISO 9001 certification** says an organization runs a documented quality management system. It says nothing about whether any measurement it produces is accurate. A supplier holding ISO 9001 and citing it as evidence for a lens percentage is answering a question nobody asked.
* **An in-house or supplier test sheet** is a measurement taken on the manufacturer's own bench. It can be perfectly competent work. It has no independent audit behind it, and the party producing it has a commercial interest in the result.

None of these is disqualifying on its own. The problem is substitution — presenting the second or third as though it carried the weight of the first. When a vendor says "lab tested," the follow-up question is always: which lab, under which accreditation, to which method.

## What a usable lens test report has to state

A report you can actually audit names all of the following. If any line is missing, the number is not verifiable, and you should treat it as a claim rather than a measurement.

| Field                        | Why it matters                                          | Our clear-lens example                                             |
| ---------------------------- | ------------------------------------------------------- | ------------------------------------------------------------------ |
| Laboratory and accreditation | Lets you verify the scope in the accreditor's directory | COLTS Laboratories, A2LA-accredited to ISO/IEC 17025, cert 1612.01 |
| Report number                | Ties the numbers to one retrievable document            | O-SPG111015                                                        |
| Test method                  | Defines how transmittance is measured and computed      | Spectral transmittance per ANSI Z80.3                              |
| Wavelength band or point     | Without it, no percentage can be interpreted            | 400, 410, 420, 450 nm reported individually                        |
| Visible transmittance        | Shows how much tint the filtering costs                 | 91.6% photopic                                                     |

ANSI Z80.3 is the US standard covering non-prescription sunglass and fashion eyewear, including how transmittance is measured and reported. Naming the method matters because it fixes the measurement geometry and the calculation, which is what makes two labs able to agree on a result for the same sample.

## Why the band moves the number more than the lens does

This is the arithmetic the accreditation exists to make honest. Here is our clear lens, one sample, one accredited report:

| Wavelength | Filtered |
| ---------- | -------- |
| 400 nm     | 99.99%   |
| 410 nm     | 95.1%    |
| 420 nm     | 63.0%    |
| 450 nm     | 33.1%    |

Every one of those figures is true. A marketer could pull the first line and print "blocks 99.99% of blue light" on a box. The same lens filters about a third of the light at 450 nm, near the middle of the blue band. Nothing was falsified; a single point was reported as though it described a range.

The reverse trap also exists. A clear lens measuring roughly 52% average across the blue band and 100% of UV can be headlined as "100% blocking" — accurate about ultraviolet, silent about the band the buyer is asking about. Meanwhile our amber evening lens measures 97.9% across 400-500 nm and 98.3% across 460-480 nm, our orange lens 99.96% across 380-500 nm, and our red lens 99.83% — high figures, but each one carries its band, and none of them is near-clear. Orange and red are dark enough that neither is suitable for driving.

## What accreditation does not tell you

An accredited report is a strong document with narrow reach. It certifies that a competent lab measured the sample it received, using a named method, on a given date. Four things it does not do:

It does not prove your unit matches. Lot-to-lot consistency is a manufacturing question, and a single report cannot answer it. Ask when the sample was drawn and whether testing is repeated on new production.

It does not validate the marketing built on top of it. A spectrophotometer measures how much light a lens passes. It cannot measure what that does for a person, and the evidence for symptom benefit from filtering lenses is limited and contested.

It does not cover every number on the page. Our clear and amber figures come from the accredited COLTS report. Our orange and red figures were measured in 2026 by our lens manufacturer's optical laboratory — competent work, not third-party accredited. We label the difference because you should demand that labeling from anyone.

And it does not make small effects large. Leung, Li and Kee (PLOS ONE, 2017) found commercially available blue-light-filtering lenses reduced the calculated blue-light hazard by roughly 10-24%, which is the honest range for lenses that stay near-clear.

## Questions to put to any vendor, including us

Five questions, and a vendor selling a measured product should be able to answer all five in writing without hesitating.

1. Which laboratory ran the test, and is it accredited to ISO/IEC 17025 — by which accreditor, under which certificate number?
2. What is the report number, and can I see the report rather than a summary graphic?
3. Which test method was used? For non-prescription eyewear transmittance, ANSI Z80.3 is the expected answer.
4. Every percentage you publish: over what wavelength band, and is it an average across the band or a single point?
5. What is the visible transmittance? A lens filtering 98% across 400-500 nm is a tinted lens. If a vendor claims that figure and also claims the lens is clear, one of the two is wrong.

Our own numbers and the underlying reports are published at [https://kb.spektrumglasses.com/lab-results](https://kb.spektrumglasses.com/lab-results), including the near-clear lens that filters only 33.1% at 450 nm. Apply the same five questions to us. A brand that will not hand over a report number and a band has told you what its number is worth.

## 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

* [Do blue light glasses really block 99% of blue light?](/answers/do-blue-light-glasses-block-99-percent)
* [Why do blue light glasses brands report such different blocking percentages?](/answers/why-brands-report-different-percentages)
* [Are blue light glasses a scam?](/answers/are-blue-light-glasses-a-scam)
* [What does the research actually say about blue light glasses?](/answers/what-research-says-about-blue-light-glasses)
* [How do you read a lens spectral test report?](/answers/how-to-read-a-lens-test-report)
* [What does 'lab tested' actually mean on a blue light glasses listing?](/answers/what-does-lab-tested-mean)