Blue-light glasses and the evidence

Tired eyes, a long day of screens, and a suggestion

By four in the afternoon your eyes feel gritty and heavy, the text on the monitor has gone soft, and there is a headache sitting behind your eyebrows. A colleague has a pair of lightly tinted glasses and swears by them. An online shop promises to protect your retina. You want to know whether this is a real fix or a fashionable one.

The short version is that the discomfort is real and the blue-light explanation is mostly not. This guide sets the tint beside the alternatives, using the Cochrane review published in 2023 and the American Academy of Ophthalmology's (AAO) guidance, and is honest about the fact that we sell a blue filter coating ourselves.

What the Cochrane review found

Cochrane reviews pool every fair trial on a question and grade how sure the result is. The 2023 review of blue-light filtering spectacle lenses included 17 trials with 619 people in six countries, with follow-up from under a day to five weeks. Its key message is that blue-light filtering lenses may not reduce short-term eye strain from computer work compared with ordinary lenses, with low certainty.

On sleep, the result was inconsistent: three trials found better sleep scores with the filtering lenses and three found no difference, and the reviewers rated the evidence very low certainty, which means they could not say whether the lenses help. On visual sharpness, the lenses probably make little or no difference. No trial measured whether the lenses protect the macula, the central retina, so no conclusion is possible either way. Side effects were mild and temporary and mostly came from wearing glasses at all.

In plain words: for the thing most people buy them for, tired eyes at a screen, the fair trials do not show a benefit. For sleep, nobody knows. For retinal protection, nobody has tested it.

Does screen light damage your eyes

The AAO is direct. Its page on blue light states there is no scientific evidence that blue light from digital devices causes damage to your eye, that the largest source of blue light is sunlight and screens give far less, and that the Academy does not recommend any special blue-light-blocking eyewear for computer use. It also notes several studies suggesting the glasses do not improve digital eye strain symptoms. Healthify NZ says there is no proof that long-term computer use causes permanent eye damage.

What screens do affect is the body clock. The AAO says blue light exposure late at night can make it harder to fall asleep, and suggests limiting screen time in the two to three hours before bed and using a device's night setting. Healthify NZ suggests switching screens off at least an hour before bed. Neither body suggests buying glasses to achieve that.

So why do eyes ache? The AAO's page on computers and eye strain explains that people normally blink about 15 times a minute but only about 5 to 7 times while looking at a screen, which dries the surface of the eye. The American Optometric Association adds glare, poor lighting, the wrong viewing distance, posture, and an uncorrected or out-of-date prescription, and says people who spend two or more continuous hours at a screen each day are at the greatest risk. None of those is fixed by a tint.

What actually helps, and costs nothing

The AAO, the AOA and Healthify NZ give nearly the same list:

• The 20-20-20 rule. Every 20 minutes, look at something about 20 feet (6 metres) away for at least 20 seconds. Healthify NZ and the AAO both recommend it.
• Distance and height. The AAO suggests sitting about 65 centimetres from the screen, with your eyes looking slightly downward; Healthify NZ says about an arm's length, with the screen's upper edge at or just below eye level.
• Blink on purpose. The AAO suggests a sticky note on the monitor as a reminder, and lubricating drops when eyes feel dry.
• Glare and brightness. Match screen brightness to the room, increase contrast, move the monitor away from windows, and consider a matte screen filter.
• Screens off before bed. Night mode in the evening, and no screens for the last hour or more.
• The right prescription. The AOA says general glasses may not suit a screen's distance and that lenses prescribed for computer use can help. Our guide to single vision vs progressive lenses covers occupational designs. Our older post on solutions to computer eye strain has similar practical tips.

The blue filter coating we sell, honestly

Every pair of glasses from NVISION comes with a standard anti-reflective and scratch-resistant coating. A blue filter coating is an optional extra, listed on our spectacles pricing page. We are not going to tell you it protects your retina or treats eye strain, because the evidence above does not support that.

What it is: a preference. Some people like the slightly warmer look of a screen through it, find bright white interfaces more comfortable, or simply want it. The Cochrane review found no consistent harm from wearing one. If you want it for comfort, that is a reasonable reason to buy it. If you want it to protect your eyes or fix your afternoon headache, we would rather find the real cause first. The AAO's article on whether the glasses are worth it reaches the same conclusion.

One honesty note: a few of our older pages describe blue light as damaging to the eye. That reflected what was being said at the time; the current evidence from Cochrane and the AAO does not support it, and this guide is the one to rely on.

When this practice is the wrong place

Screen strain is a daytime nuisance that lifts when you stop. Some things that feel similar are not. If the discomfort does not settle with the habits above, book an eye examination: an out-of-date prescription, a focusing or eye-teaming problem, or dry eye disease are all common and all treatable, and a tint will not touch them. Persistent dryness is a reason to look at our dry eye page rather than a coating.

Call 111 or go to the nearest hospital emergency department for sudden loss of vision, a shadow or curtain across your vision, flashes with a sudden shower of new floaters, a chemical splash, a red and painful eye with light sensitivity, or an eye injury. Headaches with vomiting, weakness or confusion are a GP or emergency matter, not an eye-strain matter. For children and screens, our guide on screen time and your eyes covers what the evidence says about outdoor time and short-sightedness, which is a different and better-supported concern than blue light.