“Blue light blocking” has become a selling point all by itself. Before telling you what our glasses do, we'd rather tell you what blue light does — and doesn't do. You'll choose better.
What is blue light?
It's simply the part of the visible spectrum with the shortest wavelength, roughly between 400 and 500 nanometres. It's everywhere: the sky is by far its main source. A phone or computer screen emits it too, but at a much lower intensity than daylight. An afternoon outdoors exposes your eyes to far more blue than a day in front of a screen.
What the studies say
Let's be direct: the science is more nuanced than the marketing.
- Eye strain. A Cochrane review published in 2023, which pooled 17 clinical trials, concluded that blue-light filtering lenses probably make little or no difference to short-term eye strain compared with standard lenses. Screen fatigue mostly comes from something else: we blink less, we stare at a single distance for hours, the screen is too bright or reflects a window.
- Retina. At the levels a screen emits, no serious study shows any damage to the retina. That's reassuring, and it deserves to be said clearly.
- Sleep. This is the most interesting topic. Light — blue light in particular — delays the release of melatonin in the evening. Several small studies show that amber-tinted lenses worn at the end of the day can help you fall asleep; others find no effect. The level of evidence remains modest, but this is where the idea makes the most sense.
So why wear them?
For three concrete reasons, with no medical promise:
- Comfort. An anti-reflective coating on clear lenses reduces reflections of the window or ceiling light on your lenses. Many people find the screen “softer” with it — it's subjective, and that's perfectly fine.
- The evening. An amber or orange-tinted lens filters a large share of blue. If you look at a screen late, it's a simple option to try, alongside your device's night mode and dimmed lighting.
- The ritual. Putting on your work glasses is also a routine: it reminds you to take breaks, lower the brightness, sit back a little. That matters more than you might think.
How to read a product page without being fooled
The market is full of impressive percentages: “blocks 99% of blue light”, “filters 100% of harmful rays”. Three pointers to decode them:
- A percentage without a wavelength range means nothing. A lens can filter 99% at 400 nm (the far edge of violet) and almost nothing at 450 nm, where screens emit the most. Always look for “x% between 400 and 4xx nm”.
- A perfectly clear lens cannot filter much visible blue. It's physics: filtering blue means removing part of the light, which means adding colour. A transparent lens promising 90% filtering is lying — or only talking about ultraviolet, which any plastic lens already stops.
- Blue isn't the enemy during the day. The 460–500 nm range helps keep you alert and see colours. A lens that removes it in broad daylight makes you drowsy and distorts everything you look at. For work, light filtering is enough; in the evening, a tint makes sense.
At SAY, we only display a figure when it comes from a measurement by our manufacturer, with its range. If it isn't on a product page yet, it's because we don't have it — not because we're making it up.
What these glasses don't replace
A non-prescription pair doesn't correct anything: if you squint to read, get headaches at the end of the day or your vision fluctuates, an eye exam with an ophthalmologist comes before any purchase. If you already wear prescription glasses, the answer is a blue light filter coating on your own lenses, from your optician — not a second pair on top.
Clear or tinted lenses?
Two families at SAY, two uses:
- Clear lenses (blue light filter and anti-reflective coating, no visible tint): for daytime, work and video calls. They don't change colours. Examples: MIDI, HAVANE, JADE.
- Amber or orange-tinted lenses: for the evening. They filter more but warm up colours — unsuitable for photo editing and night driving. Examples: SAFRAN, BRAISE, DUNE.
In short
No, the blue light from your screen doesn't damage your eyes. Yes, a well-chosen pair can make your screen days more comfortable and your evenings calmer — as long as you combine it with the right habits: regular breaks, suitable brightness, the correct distance. We cover them in our guide to beating eye strain.
And if you have headaches or persistent blurred vision, what you need isn't a pair of non-prescription glasses: it's an appointment with an ophthalmologist or optician.
Read next: Can you wear blue light glasses all day? · Blue light glasses: the downsides, and what eye doctors say