What UV400, UVA, and UVB ratings actually mean, and why a dark lens isn't automatically a protective one.
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What UV400 actually means
UV400 indicates a lens blocks light wavelengths up to 400 nanometers, which covers the full range of both UVA and UVB radiation — this is the standard to look for, and it's a binary pass/fail spec rather than a graded scale.
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UVA vs. UVB: why both matter
UVB rays are the primary cause of sunburn and are linked to photokeratitis (snow blindness); UVA rays penetrate deeper and are more associated with long-term eye damage like cataracts. A quality lens needs to block both, not just one.
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Why a dark lens isn't automatically protective
Lens darkness (visible light transmission) and UV protection are two entirely separate properties. A dark, tinted lens with no UV coating can actually be worse than wearing no sunglasses at all, since the pupil dilates in response to reduced visible light, letting in more unfiltered UV radiation.
What to check: Always confirm a UV400 or "100% UVA/UVB protection" label specifically, rather than assuming a darker lens means better protection. - 4
Reputable brands vs. unbranded cheap sunglasses
Established brands (Oakley, Smith, Costa, Maui Jim, Suncloud, goodr, Tifosi) reliably meet stated UV specs; extremely cheap, unbranded sunglasses sometimes fail to meet their advertised UV rating, which independent testing has occasionally confirmed. Buying from a known brand is a reasonable safeguard.
Sunglasses With Verified 100% UV Protection
| Product | Best For | Lens/Tech | Price | Score |
|---|---|---|---|---|
| Oakley Radar EV Path | Premium, verified UV400 | Prizm/Polarized | $183 | 9.4/10 |
| goodr OG | Budget, verified UV400 | Polarized | $25 | 8.9/10 |
| Suncloud Milestone | Budget, lifetime warranty | Polarized | $60 | 8.7/10 |