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Blue light blocking glasses may not actually help with eye strain or sleep quality, researchers find
Blue light glasses gained popularity over the past few years with the idea they protect our eyes against screen usage — but a new analysis shows they might not be as beneficial to our eye health as previously hoped.
Researchers reviewed data from 17 randomized controlled trials — the "current, best available evidence" they could find on the topic — and published the results Friday in the Cochrane Database of Systematic Reviews journal. The findings? Glasses marketed to filter out blue light probably make no difference to eye strain or sleep quality.
"We found there may be no short-term advantages with using blue-light filtering spectacle lenses to reduce visual fatigue associated with computer use, compared to non-blue-light filtering lenses," said Laura Downie, senior author of the review and associate professor at the University of Melbourne, Victoria, Australia, in a news release.
"It is also currently unclear whether these lenses affect vision quality or sleep-related outcomes, and no conclusions could be drawn about any potential effects on retinal health in the longer term," she added. "People should be aware of these findings when deciding whether to purchase these spectacles."
The studies they reviewed ranged in size and length, with a span of as few as five to as many as 156 participants assessed over different periods, from less than one day to five weeks. The authors said more research with longer follow-ups in more diverse populations are needed to better assess any potential effects.
More studies) should examine whether efficacy and safety outcomes vary between different groups of people and using different types of lenses," author Dr. Sumeer Singh, a postdoctoral research fellow in the Downie Laboratory, advised for future research.
Blue light, like that emanating from computer screens and smartphones, does stimulate the eyes, something that can cause sleeping problems. During the pandemic, doctors reported seeing an uptick of vision issues related to computer use including eye strain, which can lead to headaches, frontal headaches, pain around the eyes and pain behind the eyes, as well as dry eyes and related problems.
Americans were also worried about how increased screen time during lockdowns would impact their eyes. A July 2020 Alcon/Ipsos survey found 60% of people said they were concerned about the potential impact.
Sellers of blue light blocking glasses or filters promised a solution — but this isn't the first time experts have shown skepticism about their effectiveness.
Earlier this year, optometrist Dr. Robert Johnson told CBS News Pittsburgh that, while he is concerned about the impact of screens on our vision, blue light blockers aren't the answer.
"I would have patients coming in saying they just ordered blue-blocking glasses from the internet for their daughter and what was my opinion," he said. "This blue-blocking situation has been bogus basically from the get-go. ... It's one of the absurdities that come from advertising."
But while blue light blockers may not do anything, they won't hurt you. In fact, he said, "it causes absolutely no damage."
Instead of shelling out money for special shades, however, experts advise taking screen breaks.
Dr. Christopher Starr, an ophthalmologist at Weill Cornell Medicine in New York, previously told "CBS This Morning" that those glasses aren't needed as much as small breaks away from staring at the screen.
"Taking breaks is important, and I think that's the real key here, not so much glasses or filters over your screens," Starr said.
He recommends small breaks away from screens every 20 minutes. During that break, look into the distance at an object at least 20 feet away or farther, for 20 seconds or more. Also shut your eyes for 20 seconds during the break.
Johnson also goes by the "20-20-20 rule."
"For every 20 minutes, look away in excess of 20 feet for 20 seconds," he said. "That will relax your focusing mechanism that will give your eyes a break and that will make you more comfortable."
注释：
retinal: adj
表示" 视网膜的"，如：The large retinal vessels seem to be intact. 视网膜大血管看似正常。
efficacy: n
表示"功效"，means "capacity or power to produce a desired effect"，如：We are testing the efficacy of a new drug. 我们正在测试新药的功效。
emanate: v
表示" 散发；发出"，means "give out (breath or an odor)"，如：I wish I am a cup of tea, leave the misery in my heart and emanate the fragrance! 我愿意做茶，把枯涩留在心里，散发出来的都是清香。
uptick: n
表示"[商](股票)报升(成交价格比上一个交易高的成交或价格)"，means "a transaction in the stock market at a price above the price of the preceding transaction"，如：Is there an uptick in office gossip? 办公室里的流言有上升趋势吗？
frontal: adj
表示"正面的；"，means "belonging to the front part;"，如：The enemy made a frontal attack on our troops. 敌人对我们的部队发动了一次正面的进攻。
Alcon: n
表示"所关心的一切"，means "all concerned " , 文中这里指：美国爱尔康医药公司
optometrist：n
表示" 验光师"，means "a person skilled in testing for defects of vision in order to prescribe corrective glasses"，如：If you need glasses, you should see an optometrist. 若是你要配眼镜，你要找去验光师。
bogus: adj
表示" 假的；伪造的"，means "fraudulent; having a misleading appearance"，如：The telegram turned out to have been bogus. 电报原来是假的。
absurdity: n
表示" 荒谬；荒谬的事"，means "a message whose content is at variance with reason"，如：We all laughed at the absurdity in his reasoning.我们都嘲笑他的推理的荒谬。
中文简要说明：
手机计算机已成现代人高度使用的工具，长时间接触屏幕散发的蓝光有碍眼部健康，也可能影响睡眠，号称可「抗蓝光」、「滤蓝光」的眼镜镜片因而成为近年消费新宠，实效如何广受讨论。最近又有科学家发布分析研究直指，这种镜片对于眼睛保健、睡眠质量的好处不比一般镜片来得多。专家建议，看屏幕每20分钟让眼睛休息1次才是正解。
计算机、手机的屏幕发出的蓝光（blue light）会刺激眼睛，可能影响睡眠。新冠肺炎大流行期间有医师通报，与使用计算机有关的视力问题增加，包括眼睛疲劳，这会引起头痛、前额疼痛、眼周疼痛、后眼窝疼痛、眼睛干涩等问题。
美国哥伦比亚广播公司新闻网（CBS News）报导，发布于国际实证医学期刊《考科蓝系统性回顾数据库》（Cochrane Database of Systematic Reviews）的这项研究，审阅17个随机对照的试验数据，受试者少则5人、多则156人，评估期短则不到1天、长则5星期。
研究论文第一作者、澳洲墨尔本大学助理教授道尼（Laura Downie）说，「相较于非蓝光过滤镜片，想藉由滤蓝光镜片减少与操作计算机有关的视觉疲劳，可能不具短期优势」，目前还不清楚这类镜片对于视觉质量或睡眠相关后果会不会造成影响，长期下来对于视网膜健康有无潜在影响也没有结论，「大众购买这种镜片时，应该把这项发现纳入考虑」。
论文指，这方面的研究需要在不同群体持续探索，以针对不同种类镜片的潜在作用优化评估，例如功效与安全程度。
这并非蓝光镜片或滤镜的护眼效果首度受到质疑。此前已有匹兹堡执业验光师强森（Robert Johnson）表示，电子产品的屏幕对眼睛造成的冲击固然令人忧心，但这类产品并非解方，「没有改善作用，也不会造成损害」。
纽约威尔康乃尔医学院（Weill Cornell Medicine）眼科医师史塔（Christopher Starr）此前已透过「CBS今晨」（CBS This Morning）节目直言，与其使用这类镜片，还不如定时让眼睛离开屏幕稍事休息：「休息很重要，我认为这才是真正的关键，而不是在屏幕加挂滤镜或配戴这类眼镜。」
史塔建议「20-20-20」护眼守则：每20分钟让眼睛休息、离开屏幕，休息时让眼睛注视至少20呎（约18公尺）远的物体，为时至少20秒。他说：「这能放松眼睛的焦距机制，让眼睛获得休息，感觉会更舒服。」
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