10-14 生活方式导致近视

Lifestyle Causes Myopia1

Contrary to popular belief, people in East Asia are no more genetically 2 susceptible 32 to short-sightedness than any other population group, according to researchers who have analysed past studies of the problem. The epidemics 53 of myopia in countries such as Singapore and Japan are due solely 6 to changes in lifestyle, they say, and similar levels could soon be seen in many western countries as lifestyles there continue to change.

Myopia is on the increase in most places, but in countries such as Singapore it has reached extraordinary levels. There, 80 percent of 18-year-old male army recruits4 are myopic 7, up from 25 percent just 30 years ago. Employers such as the police are having problems finding people who meet their requirements. There is also an increasing incidence of extreme myopia, which can lead to blindness.

The argument is about why the rate of myopia is so much higher in East Asia than elsewhere. The conventional view is that people from the region have genetic 1 variations5 that make them more susceptible. But after reviewing over 40 studies, Morgan and Kathryn Rose， researchers from the University of Sydney, argue that there is no evidence to support this. They use several lines of evidence to debunk 86 the idea that genes 9 can explain the Asian epidemics. For instance, 70 percent of 18-year-old men of Indian origin living in Singapore have myopia, while in India itself the rate is roughly 10 percent. “The simplest explanation is that you have a massive environmental effect that is swamping7 out the genetic influence,” says Morgan. In other words, given the wrong lifestyle, everyone is susceptible to myopia.

And it looks as if those lifestyle changes are beginning to be felt in some western countries too. In Sweden, for instance, 50 percent of children aged 10 12 now have myopia. It is expected that when these children reach 18 the rate will be more than 70 percent.

“It is an impressive piece of work,” says a scientist of Ohio State University. But if the increase really is due to too much reading, she points out, then lenses that eliminate the stress of focusing on near work should help stop myopia getting any worse. In fact, studies show the lenses are of little help.

But that might be because we have not identified all the lifestyle factors involved, including ones that protect against myopia, says Morgan. For example, children who read less also tend to spend more time outdoors, where better light may reduce the need to focus precisely 11 for near vision. Studies show that children who play sport are less susceptible to myopia.

Some researchers have even proposed that diet is one of the factors contributing to the rise in myopia. They argue that eating too much refined starch 128 affects the growth of the eyeball.

注释：

1. myopia [mai5EJpiE] n. [医] 近视

2. susceptible [sE5septEbl] a. 易受影响的

3. epidemic 4 [7epi5demik] n.（流行病的）流行

4. recruit [ri5kru:t] n. 新兵

5. variation [7vZEri5eiFEn] n. [生] 变异，变种

6. debunk [di:5bQNk] vt. 指出……的错误，批判，驳斥

7. swamp [swCmp] vt.（以极大的数量或数目）吞没，使不见，使不受注意，使不起作用

8. starch [stB:tF] n. 淀粉

生活方式导致近视

据研究人员对以往研究的分析，东亚地区的人并非因遗传因素而较之其他地区的人更容易患近视。这一点与普遍流行的看法正相反。研究人员说，在诸如新加坡和日本等国家，近视的流行完全是因为生活方式改变所致；随着许多西方国家生活方式的不断变化，类似的情况也会很快发生。

近视在大多数地区都呈上升趋势，但是在新加坡等国家中，近视率已经达到了超乎寻常的水平。在那里，18岁男性新兵中80％的人都是近视，而仅在30年前这个比例则是25％。像警察这样的雇主们现在很难找到符合他们条件的人选，而且可能导致失明的高度近视的比例也在不断上升。

人们争论的问题是为什么东亚地区的近视率远远高于其它地区。传统的看法是，这一地区的人因遗传变异而更易患近视。但是在对40多项研究进行详查后，悉尼大学的研究人员摩根和凯瑟琳·罗斯认为没有证据支持这一论点。他们用几组不同的证据对基因引发亚洲近视潮的观点进行了驳斥。比如，在新加坡定居的18岁印度裔居民中有70％患近视，而在印度，同龄人患病的比例只有大约10％。“最简单的解释是，巨大的环境作用超过了遗传的影响，”摩根这样说道。换句话说，假如生活方式不适当，每个人都容易患近视。

在有些西方国家，生活方式似乎也开始在改变。比如在瑞典，12岁的孩子中有50％患有近视。预计当这些孩子长到18岁时，近视率将超过70％。

“这是一项很引人注意的研究，”俄亥俄州立大学的一位科学家说道。但是她又指出，如果近视的增多确实是因读书过度所致，那么消除近距离工作时眼肌紧张的眼镜应该有助于防止近视的进一步加剧。可是实际上，研究表明眼镜没有起到什么帮助作用。

摩根对此说道，这种结果的出现或许是因为我们尚没有识别所有与近视相关的生活方式因素，包括对视力有保护作用的因素。比如，读书少一些的孩子花在户外的时间也相对多些。在那里，较好的光线减少了眼球近距离聚焦的需要。研究表明参加体育锻炼的孩子不大容易患近视。

有一些研究者甚至提出，饮食是导致近视率上升的原因之一。他们认为食用过多的精制淀粉食品影响眼球的生长。