The Myopia Crisis and Why Children Should Spend More Time Outdoors近視危機下兒童需增加戶外活動

文/阿里安娜·恩俊·查 譯/王恒娟 審訂/袁圓

By Ariana Eunjung Cha

近視，又稱短視眼，正在成為一種在全球蔓延的疾病。

[2]在美國和歐洲，近二分之一的青年患有近視，這一比例是其祖輩同齡時期的兩倍。中國的近視問題更加嚴峻，青少年的近視率為80%到90%，而60年前該比例僅為10%到20%。

[3]為什么有的人近視（看近物清楚，看遠物模糊），有的人直到白發暮年仍然保持1.0的視力？研究人員過去一直認為這主要是由基因決定的，而現在，他們更關注環境因素，更確切地說是特定的環境因素：成長過程中的戶外活動時間。

Myopia1myopia近視眼。, or nearsightedness2nearsightedness短視眼。, is becoming a problem of epidemic3epidemic流行性的。proportions for the world.

[2] Roughly half of young adults in the United States and Europe have it, double the percentage when their grandparents were the same age. In China, the trend is even more alarming—with 80 percent to 90 percent of teens and young adults with the condition versus 10 percent to 20 percent 60 years ago.

[3] Researchers used to think that the explanation for why some people become nearsighted (able to see close objects more clearly than those far away)and why some continue to have 20/20 vision420/20 vision美國視力檢測標準，相當于中國的1.0視力（在距視力表20英尺或6米處，能夠看清“正常”視力所能看到的東西）。until they are old and gray was mostly a function of our genes. These days the focus is on environmental factors—or, more accurately, one specif i c type of environmental factor: How much time you spend outdoors while growing up.

[4] In a new study published in the Journal of the American Medical Association, researchers report that children who spent 40 minutes more time outdoors a day were much less likely to be diagnosed with myopia.The research involved 1,903 children in grades 1 through 12 at a dozen schools in the large southern Chinese city of Guangzhou near Hong Kong.

[5] Half of the schools added one additional 40-minute class of outdoor activities during the day, and parents were encouraged to take their children outdoors after school and during the weekends. The remaining schools,which kept their normal schedule,served as a control.

[6] Led by Mingguang He of Sun Yatsen University, the study team found that after three years 30.4 percent of the children in the first group had myopia versus 39.5 percent of the control group.

[4]發表在《美國醫學會雜志》的一項新研究表明，每天戶外活動時間增加40分鐘，孩子患上近視的可能性更小。該研究在中國南部臨近香港的大城市廣州展開，選擇了1903名學生作為研究對象，他們來自12所學校，年級分布從小學一年級到高中三年級都有。

[5]其中的6所學校每天增加了一節40分鐘的戶外活動課，同時鼓勵家長在放學后和周末多帶孩子在室外活動。另外的6所學校則作為控制組，保持原先的時間安排。

[6]在中山大學何明光教授的帶領下，該研究小組發現，三年后實驗組學生的近視率為30.4%，控制組為39.5%。

[7]這說明近視率相對降低了23%。

[8]近視是指光線進入眼睛后焦點落在視網膜之前而導致視物模糊。現代社會，借助框架眼鏡、隱形眼鏡和激光矯正手術，近視倒沒有帶來很大麻煩。但是，對有些患者而言，近視則可能引發更嚴重的眼科疾病，如白內障或視網膜脫落。研究人員通過對雛雞的實驗推斷，較強的光線會刺激多巴胺的釋放，從而有可能防止兒童在成長過程中眼球變形。

[7] That’s equivalent to a 23 percent relative reduction in incident myopia.

[8] Nearsightedness is a condition that occurs when the light coming into an eye doesn’t focus on the retina5retina視網膜。but in front of it, making things look blurry.It’s usually only a minor inconvenience for many people in today’s modern world, with options for eyeglasses,contact lenses and laser surgeons. But for some it can lead to more serious eye disease, such as cataracts6cataracts〈醫〉白內障。or retinal detachment7retinal detachment視網膜脫落。. Based on studies with chicks, researchers have theorized that bright light triggers the release of dopamine8ine〈生化〉多巴胺。, which might help keep the eyes from becoming misshapen as they develop as a child ages.

[9] The results of the Guangzhou study, while remarkable, were not as marked as the researchers expected.

[10] Based on previous, smaller studies they had hoped the reduction might be as high as 50 percent. That may be explained by the fact that the outdoor exposure was increased by 40 minutes while in some previous studies it has been as much as 80 minutes.

[9]該項研究雖取得了顯著成果，但并未達到研究人員的期望值。

[10]根據之前較小規模的研究實驗，研究人員本預計近視率能夠降低50%。他們認為影響此次實驗結果的原因或許是因為給學生增加的戶外活動時間由之前研究中的80分鐘減少為40分鐘。

[11]澳大利亞國立大學的研究員伊恩·摩根評估稱，兒童每天需要在陽光下活動三小時左右才能降低近視的發生率。如果在晴天透過太陽眼鏡看外物，進入眼睛的光照強度約為10000勒克斯；陰天或蔭蔽處約為2500勒克斯；教室或辦公室內則為500勒克斯。

[11] In total, researcher Ian Morgan from the Australian National University in Canberra has estimated that children need to spend about three hours per day in sunshine to reduce their risk of nearsightedness. In brightness terms that’s about 10,000 lux9lux勒克斯，照度的國際單位。if you’re looking around through sunglasses on a cloudless day. In comparison, an overcast day or deep shade measures in at about 2,500 lux, and a classroom or office 500 lux.

[12] The problem is that many children, especially those in the United States, where recess time in public schools can be limited to 20 minutes,and in parts of Asia, where the school day can be two or more hours longer than in Western countries, spend far less time outdoors.

[13] “The higher prevalence of myopia in east Asian cities seems to be associated with increasing educational pressures, combined with lifestyle changes, which have reduced the time children spend outside,” Morgan wrote in a paper published in the Lancet10Lancet《柳葉刀》，1823年湯姆·魏克萊（Thomas Wakley）以外科手術刀“柳葉刀（lancet）”為名創立的刊物，現成為世界權威醫學雜志。in 2012.

[12]問題是許多兒童在戶外待的時間太短，特別是美國公立學校的孩子，課間僅有20分鐘的休息時間，而在部分亞洲國家，孩子們每天在校時間比西方國家要長兩個小時，甚至更多。

[13] 2012年，摩根在醫學雜志《柳葉刀》上發表論文寫道：“生活方式的改變和日益增長的學習壓力，使得兒童戶外活動時間減少，導致了亞洲東部城市近視率的大幅提高。”

[14]數據顯示，近視發病率呈現城鄉兩極分化的趨勢，是因為農村孩子待在戶外的時間更多，這也驗證了摩根的理論。

[15]以尼泊爾為例，農村地區15歲孩子的近視率不足3%，而城市中10歲孩子的近視率就達到了10.9%，12歲時為16.5%，15歲時為27.3%。

[16]針對《美國醫學會雜志》發表的這篇研究報告，約翰·霍普金斯大學醫學院的邁克爾·X.雷普卡在其評論文章中提出，針對戶外活動類型的研究需進一步開展，因其有利于指導學校開設戶外活動的課程。

[14] This theory is also supported by data that shows a rural-urban split among children who become nearsighted with the assumption being that those in the countryside tend to spend more time under the sun.

[15] Take Nepal, for example. The prevalence of myopia in 15-year-olds is less than 3 percent in rural children but ranged from 10.9 percent in 10-year-old children, 16.5 percent in 12-year-olds,to 27.3 percent in 15-year-olds in urban children.

[16] In an editorial11editorial社論，評論。accompanying the publication of the JAMA study,Michael X. Repka of the Johns Hopkins University School of Medicine said that further study is needed on the kinds of outdoor activities that might be beneficial to guide the implementation of outdoor activities in schools.

[17] “Establishing the long-term effect of additional outdoor activities on the development and progression of myopia is particularly important because the intervention is essentially free and may have other health benefits,” Repka wrote. ■

[17]雷普卡寫道：“在近視的發生與發展階段，開展更多長期有效的戶外活動極為重要，因為這一干預手段本身是免費的，而且還能帶來其他健康方面的益處。” □