Don’t buy blue-light-blocking glasses to “protect your vision,” and don’t believe claims that staring at screens for months will ruin your eyes — but severe eye pain, redness, and swelling require immediate medical attention.

Blue-light-blocking lenses provide no real benefit. Skipping them saves you money, and there’s no evidence they reduce eye strain or protect the retina compared to regular lenses. While they may ease temporary eye dryness and fatigue from screen use, the only things that truly damage eyes are welding arcs, ultraviolet radiation, lasers, and acute angle-closure glaucoma.

These glasses cost nothing, and you’ll also avoid paying the extra few hundred to a few thousand yuan for blue-light-blocking lenses.

A 2023 Cochrane systematic review analyzed 17 randomized controlled trials, each enrolling 5 to 156 participants, with follow-up periods ranging from less than a day to five weeks. Due to limited data, significant differences in participant numbers across trials, and inconsistent follow-up times, the authors did not calculate a pooled overall effect size. All results below compare outcomes to those of people wearing regular lenses. After less than a week of use, self-reported eye fatigue showed “likely no difference” between groups, with low certainty of evidence. One trial involving 120 participants found a 9.76-unit difference between groups, with a 95% confidence interval ranging from -33.95 to 53.47 — a range spanning both positive and negative values, indicating no meaningful difference. Critical flicker fusion frequency, an objective measure of eye fatigue, also showed “likely almost no difference” between groups, with low certainty of evidence. Best corrected visual acuity after wearing the glasses showed “probably no effect” either, with a difference of 0.00 logMAR between groups (95% CI: -0.02 to 0.02). This result came from just one study with 156 participants, resulting in moderate certainty of evidence. Whether these glasses affect daytime alertness remains unclear, based on two trials with 42 participants and very low certainty of evidence. The review also found no evidence supporting any retinal protective effects of blue-light-blocking lenses.

Screen use commonly causes eye strain and dryness, which manifests as soreness, irritation, and temporary blurriness. These symptoms usually ease with rest and frequent blinking — they are temporary and do not permanently damage vision. This is a widely accepted consensus in ophthalmology, but it is not a conclusion drawn from the Cochrane review referenced here, so this point is rated as grade C evidence. The only factors that can cause irreversible eye damage in a short period are intense light sources such as welding arcs, ultraviolet radiation, and lasers. Eye injury from welding arcs, known as photic keratitis, is a legally recognized occupational disease; protection requires specialized goggles and face shields, not blue-light-blocking lenses — see Section 19, Item 10 on protection from dust, noise, and chemical hazards. For people staying up late and staring at screens, the only true emergency is severe eye pain, redness, a rainbow halo around lights, headache, nausea, and vomiting — these are signs of acute angle-closure glaucoma, which can damage the optic nerve within days and requires immediate emergency care — see Section 13, Item 6 on ophthalmic emergencies. This condition is more likely in people over 50, those with hyperopia, and those with a shallow anterior chamber, especially if they have dilated pupils in low light and maintain a forward-leaning posture for long periods. Chronic dry eye caused by prolonged screen use can also become a long-term medical issue requiring treatment, rather than a symptom that goes away after a good night’s sleep. If you experience persistent eye discomfort or a noticeable decline in vision, consult an ophthalmologist to identify the root cause — don’t assume a new pair of lenses will resolve the problem. For advice on preventing myopia in children and teens, see Section 30, Items 4, 12, and 9: get at least two hours of outdoor time daily, undergo mydriatic refraction tests, and avoid products marketed as “myopia cures.”

Singh S, Downie LE, Anderson AJ, Keller PR, White SJ, Ang M, Wolffsohn JS (2023). Blue-light filtering spectacle lenses for visual performance, sleep, and macular health in adults. Cochrane Database of Systematic Reviews, 8, CD013244. https://doi.org/10.1002/14651858.CD013244.pub2；American Academy of Ophthalmology (2024). Computers, Digital Devices, and Eye Strain（「You may have heard that looking at a computer, smartphone, or other digital screen for long periods of time will permanently damage your eyes. Thankfully, this is not true.」）. https://www.aao.org/eye-health/tips-prevention/computer-usage；国家卫生健康委等四部门 (2024). 关于印发《职业病分类和目录》的通知（国卫职健发〔2024〕39 号，「三、职业性眼病」第 2 项电光性眼炎，「六、物理因素所致职业病」第 6 项激光所致眼（角膜、晶状体、视网膜）损伤）. https://www.gov.cn/gongbao/2025/issue_11886/202502/content_7007111.html