Written and maintained by CASRAI Editorial Board
Last updated
General product and regulatory information for clinic and lab staff. It is not medical advice and does not recommend lenses for any individual.
Short answer
FL-41 is the name of a rose-coloured lens tint sold as “migraine glasses” for light sensitivity. In the United States, FDA lists the broader category, light attenuation lenses for migraine-associated light sensitivity (product code QEO), as a Class 1 device under 21 CFR 882.5811, intended to be adjunctive to other migraine therapies. One peer-reviewed study of FL-41 lenses tested people with chronic ocular pain, not migraine.
Definition and scope
“FL-41 glasses”, “migraine glasses”, “light sensitivity glasses” and “FL-41 lenses” are used for the same kind of product: spectacle lenses with a tint intended to reduce how much light, and which wavelengths, reach the eyes of a person who is bothered by bright or fluorescent light. This page covers what the product category is and how it is classified. It does not cover diagnosing or treating migraine.
Two points keep the terms straight:
- FL-41 is a tint; QEO is a regulatory category. FDA’s classification record for QEO names the device “light attenuation lenses for migraine-associated light sensitivity” and does not mention FL-41. Other tints could fall in the same category, so the two should not be treated as synonyms.
- Light sensitivity is not the same as migraine. The FDA definition refers to patients “diagnosed with migraine”. A diagnosis is a clinical decision made outside the supply process.
How FDA classifies migraine light-attenuation lenses
Source: FDA Product Classification database, product code QEO, and the openFDA device classification API (checked 2026-10-30).
- Definition: devices that limit light incidence of specific wavelengths to the eyes and are intended to decrease the impact of light sensitivity in patients diagnosed with migraine. The lenses can be mounted on a spectacle frame, clips or other holders.
- Intended role: the definition says the device is intended to be adjunctive to other therapies for migraine-associated light sensitivity.
- Regulation and class: 21 CFR 882.5811, device class 1, neurology review panel.
- Submission type: FDA’s classification page lists the code as exempt from premarket notification (510(k)). FDA’s general note on exempt class I devices says manufacturers must still register their establishment, and the openFDA record lists De Novo number DEN250026 against the code.
- Related categories: the same definition states that nonprescription sunglasses and prescription spectacle lenses are separately classified under 21 CFR 886.5850 and 886.5844.
For background on how premarket pathways and device classes arose, see the CASRAI entry on the Medical Device Amendments of 1976.
What one FL-41 study did and found
Reyes N, Huang JJ, Choudhury A, et al. “FL-41 Tint Reduces Activation of Neural Pathways of Photophobia in Patients with Chronic Ocular Pain.” American Journal of Ophthalmology, 2023;259:172-184 (PubMed Central author manuscript PMC10939838, checked 2026-10-30).
- Design: each participant was scanned with functional MRI without, then with, FL-41 lenses in a single session. 28 people were enrolled and 25 analysed.
- Population: chronic ocular pain. It was not a migraine trial.
- Lens: rose-coloured lenses from one manufacturer (Axon Optics) that attenuated a wide spectrum of wavelengths, approximately 430-630 nm. That is a broad band, not a single narrow wavelength.
- Result: mean light-evoked unpleasantness (0-100 scale) was 52.5 without and 39.7 with the lenses (p = 0.04). Ratings with a black screen were unchanged.
What the evidence does and does not show
The authors list their own limits. Use them as a checklist when a product page cites this study.
| Question to ask of a claim | What the study reports |
|---|---|
| Was the population people with migraine? | No. Participants had chronic ocular pain. |
| Was there a control lens? | No neutral-density control lens was used, so the effect may reflect an overall reduction in light rather than a wavelength-specific effect. |
| Was the order of conditions varied? | No. Everyone was scanned without the lenses first, so order effects are possible. |
| How large and varied was the sample? | Small (25 analysed), mostly male, with varied comorbid conditions. |
| Does it show a change in migraine frequency? | It did not measure migraine frequency. |
Where it matters for labs, clinics and supply decisions
Staff who handle product listings, patient handouts or supply catalogues can use the sources above to check wording:
- Intended-use wording. The FDA definition frames the category as adjunctive to other migraine therapies for light sensitivity. A listing that presents lenses as a stand-alone cure goes beyond that definition.
- Study citations. A listing that cites the Reyes study for migraine benefit is citing a chronic ocular pain population (see the table).
- Regulatory wording. Class 1 and 510(k) exempt describe the classification. They are not the same as saying FDA reviewed or endorsed a specific lens.
Practices that stock eyewear can compare this with the general lists in the optometry clinic supply checklist. For how device problems are reported once a product is in use, see medical device reporting (MDR).
Common misunderstandings
“FL-41 glasses are FDA approved.”
The QEO category is Class 1 and listed as exempt from 510(k) premarket notification. Exempt is a classification status, not an approval of a particular product.
“FL-41 and migraine glasses are different products.”
The terms overlap in common use. FL-41 names a tint, while “migraine glasses” is a consumer label. Neither appears in the regulation as a brand or tint name; the regulation describes lenses that limit specific wavelengths.
“The study proves FL-41 lenses prevent migraine.”
It does not. It looked at brain activation and unpleasantness ratings in chronic ocular pain during a light stimulus.
FAQ
Are FL-41 glasses a medical device?
Lenses marketed for migraine-associated light sensitivity fall under FDA product code QEO, 21 CFR 882.5811, Class 1 (checked 2026-10-30).
Do FL-41 lenses cure migraine?
Nothing cited on this page says so. FDA’s definition describes the lenses as adjunctive to other therapies for migraine-associated light sensitivity.
Are FL-41 glasses the same as blue light glasses?
The FDA record and the study cited here do not compare them. What they do show: the studied FL-41 lens attenuated roughly 430-630 nm, and FDA classifies nonprescription sunglasses and prescription lenses under different regulations from QEO.
What is the difference between migraine glasses and light sensitivity glasses?
FDA’s category name ties the lenses to light sensitivity in patients diagnosed with migraine. A product sold only as “light sensitivity glasses” is not necessarily labelled for that use; check the manufacturer’s stated intended use.
Sources
- FDA, Product Classification, product code QEO, “Light attenuation lenses for migraine-associated light sensitivity”, regulation 882.5811, Class 1: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpcd/classification.cfm?id=QEO (checked 2026-10-30).
- openFDA device classification API, product code QEO, data last updated 2026-10-19: https://api.fda.gov/device/classification.json?search=product_code:QEO (checked 2026-10-30).
- Reyes N, Huang JJ, Choudhury A, et al. Am J Ophthalmol. 2023;259:172-184: https://pmc.ncbi.nlm.nih.gov/articles/PMC10939838 (checked 2026-10-30).
