好英语网科学保护视力：关于用眼健康的几大常识和误区
If you were ever scolded as a child for reading in the dark, or if you have used blue-light-blocking glasses when working on a computer, you might have incorrect ideas about eye health.
如果你小时候因为在光线不好的地方读东西而受到责备，或者用电脑的时候戴防蓝光眼镜，那么关于眼睛健康，你可能有一些不正确的看法。
About four in 10 adults in the United States are at high risk for vision loss, according to the Centers for Disease Control and Prevention. But many eye conditions are treatable or preventable, said Dr. Joshua Ehrlich, an assistant professor of ophthalmology and visual sciences at the University of Michigan.
根据美国疾控中心的数据，全美每十个成年人中就有四个存在视力丧失的高风险。密歇根大学眼科和视觉科学助理教授约书亚·埃尔利希博士说，其实许多眼疾是可以治疗或者预防的。
Here are nine common beliefs people have about eye health, and what experts have to say about them.
以下是关于眼睛健康的九个常见说法，以及专家的意见。
Reading a book or looking at an electronic device up close is bad for your eyes.
看书或者使用电子设备的时候，凑得过近对视力有害。
True. Our eyes are not meant to focus on objects close to our face for long periods of time, said Dr. Xiaoying Zhu, an associate clinical professor of optometry and the lead myopia researcher at SUNY College of Optometry in New York City. When we do, especially as children, it encourages the eyeball to lengthen, which over time can cause nearsightedness, or myopia.
正确。纽约州立大学视光学院的临床眼视光副教授、近视首席研究员朱晓颖（音）博士说，我们的眼睛不应该长时间盯着靠近面部的物体。如果经常这样，尤其是在孩童阶段，会导致眼轴变长，长此以往就变成了近视。
To help reduce the strain on your eyes, Dr. Zhu recommends following the 20-20-20 rule: After every 20 minutes of close reading, look at something at least 20 feet away for at least 20 seconds.
为了帮助减少眼睛的压力，朱晓颖建议遵循20-20-20规则：近距离阅读20分钟后，至少要看20英尺以外（大约六米开外）的东西至少20秒。
Reading in the dark can worsen your eyesight.
在暗处看东西会导致视力下降。
False. However, if the lighting is so dim that you need to hold your book or tablet close to your face, that can increase the risks mentioned above and create eyestrain, which can cause soreness around the eyes and temples, headache and difficulty concentrating. But these are usually temporary symptoms, Dr. Zhu said.
错误。不过，在光线不好的时候，你会不由自主地凑近书或者平板电脑，从而增加前述风险，造成视疲劳，导致眼睛和太阳穴周围酸痛、头疼和注意力不集中的状况。但朱晓颖说，这些通常都是暂时性的症状。
Spending more time outside helps eyesight.
多待在户外对视力有好处。
True. Some research (mostly focused on children) suggests that outdoor time can reduce the risk of developing myopia, said Maria Liu, an associate professor of clinical optometry at the University of California, Berkeley. Experts don’t fully understand why this is, but some research suggests that bright sunlight may encourage the retina to produce dopamine, which discourages eye lengthening (though these experiments have mostly been conducted with animals, Dr. Zhu said).
正确。加州大学伯克利分校临床眼视光副教授刘悦说，一些研究（主要针对儿童）表明，多待在户外可以降低患近视的风险。对于背后的原因，专家并不完全理解，但一些研究表明，明亮的阳光可能会促进视网膜产生多巴胺，从而阻止眼轴变长（尽管朱晓颖说，这些实验主要是在动物身上进行的）。
Too much ultraviolet light can harm eyesight.
过多的紫外线会损害视力。
True. There is a reason experts say not to stare at the sun. Too much exposure to ultraviolet A and B rays in sunlight can “cause irreversible damage” to the retina, Dr. Ehrlich said. This can also increase your risk of developing cataracts, he said.
正确。专家说不要盯着太阳看是有原因的。埃尔利希说，过多地暴露在阳光下，紫外线中的UVA和UVB会对视网膜造成“不可逆转的损害”。这还会增加患白内障的风险，他说。
Too much UV light exposure can also increase the risk for developing cancers in the eye, Dr. Ehrlich said — though this risk is low. Wearing sunglasses, glasses or contacts that block UV rays can offer protection.
埃尔利希说，过多的紫外线照射也会增加眼睛患癌症的风险——尽管这种风险很低。佩戴太阳镜、眼镜或隐形眼镜可以阻挡紫外线。
Taking a break from wearing glasses can prevent your eyesight from getting worse.
隔一阵子摘下眼镜可以防止视力下降。
False. Some patients who need glasses tell Safal Khanal, an assistant professor in optometry and vision science at the University of Alabama at Birmingham, that they don’t wear their glasses all the time because they think it will make their condition worse. “That’s not true,” he said. If you need glasses, you should wear them.
错误。一些需要佩戴眼镜的患者告诉阿拉巴马大学伯明翰分校眼视光学和视觉科学助理教授萨法尔·卡纳尔，他们不会一直戴眼镜，因为他们认为这会让视力下降。“不是这样的，”他说。如果你需要眼镜，就应该戴上。
Even a little blue light from screens is damaging to your eyes.
即使是来自屏幕的一点点蓝光，也会损害你的眼睛。
False. While some research has found that exposure to blue light can damage the retina and potentially cause vision problems over time, no solid evidence has confirmed that this happens with typical exposures in humans, Dr. Ehrlich said. There’s also no evidence that wearing blue-light-blocking glasses will improve eye health, he added.
错误。埃尔利希说，虽然一些研究发现，长期暴露在蓝光下会损害视网膜，并可能导致视力问题，但没有确凿的证据可以证实，在人类的典型暴露情况下会发生这样的情况。他还说，也没有证据表明戴防蓝光眼镜能改善眼睛健康。
But screens can be bad for eyesight in the other ways described above, including by causing dry eyes, Dr. Zhu said. “When we stare at a screen, we just don’t blink as often as we should,” she said, and that can cause eyestrain and temporary blurred vision.
但朱晓颖说，屏幕可能会以上述其他方式对视力造成损害，包括导致眼睛干涩。她说，“当我们盯着屏幕时，眨眼频次就会减少，”这会导致眼睛疲劳和暂时性的视力模糊。
Smoking is bad for eye health.
吸烟伤害眼睛健康。
True. A 2011 C.D.C. study linked smoking with self-reported age-related eye diseases in older adults, including cataracts and age-related macular degeneration, a disease where part of the retina breaks down and blurs your vision. Toxic chemicals in cigarettes enter your bloodstream and damage sensitive tissues in the eyes including the retina, lens and macula, Dr. Khanal said.
正确。美国疾控中心在2011年的一项研究中，将吸烟行为与老年人自述的与年龄相关的眼部疾病联系在一起，这些疾病包括白内障和老年性黄斑变性，后者是一种视网膜部分受到破坏导致视力模糊的疾病。卡纳尔说，香烟中的有毒化学物质会进入你的血液，损害眼睛里的敏感组织，包括视网膜、晶状体和黄斑。
Carrots are good for your eyes.
胡萝卜对眼睛有益。
True. While a diet full of carrots won’t give you perfect vision, some evidence suggests that the nutrients in them are good for eye health. One large clinical trial, for instance, found that supplements containing nutrients found in carrots, including antioxidants like beta-carotene and vitamins C and E, could slow the progression of age-related macular degeneration.
正确。虽然吃很多胡萝卜不会给你带来完美的视力，但一些证据表明，其中的营养物质对眼睛健康有益。比如，一项大型临床试验发现，一些包含胡萝卜中的各种营养物质的补充剂，包括β-胡萝卜素和维生素C和E等抗氧化剂，可以减缓与年龄相关的黄斑变性的进展。
Following an antioxidant-rich diet won’t necessarily prevent an eye disease from occurring, but it can be helpful “particularly for people with early macular degeneration,” Dr. Ehrlich said.
埃尔利希说，富含抗氧化剂的饮食不一定能预防眼疾的发生，但可能会有所帮助，“特别是早期黄斑变性患者”。
Worsening eyesight is an inevitable part of aging.
视力下降是衰老不可避免的一部分。
False. Most causes of declining eyesight in adulthood — including age-related macular degeneration, cataracts and glaucoma — are preventable or treatable if you catch them early, Dr. Ehrlich said. If your vision is starting to wane, don’t dismiss it as “just aging,” he added. Seeing an optometrist or ophthalmologist right away (or regularly, every year) will give you the best chance of staving off these conditions, he said.
错误。埃尔利希说，成年期视力下降的大多数原因——包括老年性黄斑变性、白内障和青光眼——如果及早发现，都是可以预防或治疗的。如果你的视力开始下降，不要认为这只是“老了”，他说，立即（或每年定期）去看视光或眼科医生，会帮你尽可能避免这些情况。