近视对亚洲孩童的影响大过美国的白人孩童


  【24drs.com】根据在线发表于8月14日眼科学期刊的一篇文章,远视是亚洲和非西班牙裔白人(NHW)之南加州孩童最常见的眼睛屈光疾病,但是,亚洲孩童的近视盛行率相对高过远视或散光。
  
  南加大洛杉矶分校预防医学科Ge Wen等人进行了一个以人口为基础的横断面研究,属于「Multi-Ethnic Pediatric Eye Disease Study (MEPEDS)」这项研究的一部份。
  
  研究者纳入了居住在加州洛杉矶和河滨郡、年纪6-72个月的1,501名非西班牙裔白人孩童和1,507名亚洲孩童;研究者对家长或监护人进行了居家访谈,并且比较孩童的眼科检查,包括散瞳验光。
  
  研究者发现,近视的整体盛行率在非西班牙裔白人孩童是1.20% (95%信心区间[CI],0.76% - 1.89%),亚洲孩童则是3.98% (95% CI,3.11% - 5.09%),盛行率在性别和各年龄之间并无显著差异。
  
  他们也发现,远视的盛行率在非西班牙裔白人孩童是25.7% (95% CI,23.5% - 27.9%),亚洲孩童是13.5% (95% CI,11.8% - 15.3%);非西班牙裔白人孩童无性别或年纪差异,亚洲孩童方面,女孩比男孩更可能患有远视(16.2% vs 10.8%;P = .002)。
  
  研究者发现,散光(≧1.5屈光度)的整体盛行率在非西班牙裔白人孩童是6.33% (95% CI,5.21% - 7.68%),亚洲孩童是8.29% (95% CI, 7.01% - 9.80%);另外,散光3.00屈光度以上的整体盛行率,非西班牙裔白人孩童是0.73% (95% CI,0.41% - 1.31%),亚洲孩童是1.19% (95% CI,0.76% - 1.88%)。他们发现盛行率并无性别差异,但是,散光1.5屈光度以上者,在非西班牙裔白人孩童中,盛行率随年纪增加而降低(P < .0001),亚洲孩童则没有差异。
  
  和之前的MEPEDS研究资料比较时,研究者发现,非西班牙裔白人孩童的近视盛行率(1.20%)是四个族裔中最低的,其它各种族孩童的盛行率分别是亚裔(3.98%)、西班牙裔(3.7%)与黑人(6.6%;各项比较之P < .0001);类似的是,和另一篇MEPEDS报告比较时,非西班牙裔白人孩童的散光(≧1.5屈光度)盛行率也是四个族裔中最低的。
  
  研究者指出,基因和生活型态以及环境因素,造成各种族之间的这些差异。
  
  资深作者、伊利诺大学伊利诺眼耳专科医院眼科部主任Rohit Varma教授表示,许多近视孩童的父母也有近视,亚裔孩童确实存在有某个程度的遗传倾向。
  
  此外,一般也认为,亚裔孩童的父母会在孩童很小时就鼓励孩童开始阅读或类似的近距离工作,越早开始花越多时间在这类近距离工作时,近视盛行率或比率就越高;当孩童从事越多这类近距离工作,如近距离玩计算机游戏或者使用iPad阅读或看影片,眼睛的发育就会有不同影响。
  
  Varma医师表示,相对的,研究也显示,非西班牙裔白人孩童参与相当多的户外活动,包括以较远的距离看东西、游泳、参与激烈运动者,则比较不会发生近视;而这个因素也造成远视的差异,约半数的亚裔孩童有远视。这两组的散光比例相当。
  
  另一篇类似研究的共同作者、约翰霍普金斯大学Wilmer眼科研究中心眼科与儿科教授Michael X. Repka医师表示,这篇新研究以另一种方式告诉我们已经知道的差异,而这差异可能比一般人所推测的小。
  
  不过,Repka医师警告不要引用这个「接近的理论」,因为研究的是6-72个月这个特殊的年龄层,这个年龄层的屈光差异是相当小的,远视方面,并不代表这些孩童需要戴眼镜,这是需提出的警告之一;对于远视病患,或许只有相当少患者需要矫正。研究结果确实发现有这些屈光异常,但是并无病理影响。
  
  不过,研究者指出,最新的研究结果可能在美国各地皆有普遍性,因为这是篇人口基础研究。Varma医师表示,选定进行这项研究的区域,与加州和美国有类似的社会人口统计学和年龄分布,曾进行眼科检查的参与率达80%- 87% 。
  
  Repka医师认同此研究具有普遍性,而人口研究的结果并不会令人惊讶,因为这类研究无法告诉我们要做什么,但是有助于帮助实务指南,以及如何在这个数据背景之下对待个别患者。
  
  资料来源:http://www.24drs.com/professional/list/content.asp?x_idno=7006&x_classno=0&x_chkdelpoint=Y
  

Myopia May Affect Asian Kids More Than White Kids in US

By Larry Hand
Medscape Medical News

Hyperopia, or farsightedness, is the most common refractive eye error in Asian and non-Hispanic white (NHW) Southern California children overall, but myopia, or nearsightedness, is "relatively more prevalent" among Asian children than hyperopia or astigmatism, according to an article published online August 14 in Ophthalmology.

Ge Wen, MSc, from the Department of Preventive Medicine, University of Southern California, Los Angeles, and colleagues conducted a population-based, cross-sectional study as part of the Multi-Ethnic Pediatric Eye Disease Study (MEPEDS).

The investigators enrolled 1501 NHW and 1507 Asian children aged 6 to 72 months in Los Angeles and Riverside Counties in California. The researchers conducted in-home interviews with parents or guardians and comprehensive eye exams for the children, including cycloplegic autorefraction.

Researchers found the overall prevalence of myopia to be 1.20% (95% confidence interval [CI], 0.76% - 1.89%) among NHW children and 3.98% (95% CI, 3.11% - 5.09%) for Asian children. They found no significant differences in prevalence between sexes or ages.

They determined the prevalence of hyperopia to be 25.7% (95% CI, 23.5% - 27.9%) in NHW children and 13.5% (95% CI, 11.8% - 15.3%) in Asian children. They found no sex or age differences in prevalence for NHW children, but among Asian children, girls were more likely to have hyperopia than boys (16.2% vs 10.8%; P = .002).

The researchers found the overall prevalence of astigmatism (?1.5 diopters) to be 6.33% (95% CI, 5.21% - 7.68%) in NHW children and 8.29% (95% CI, 7.01% - 9.80%) among Asian children. They also found the overall prevalence of astigmatism of 3.00 diopters or more to be 0.73% (95% CI, 0.41% - 1.31%) in NHW and 1.19% (95% CI, 0.76% - 1.88%) in Asian children. They found no sex differences for prevalence, but for an astigmatism of 1.5 or more diopters, prevalence was lower in each subsequent older age category in NHW children (P < .0001), but not in Asian children.

When compared with data from previous MEPEDS research, the investigators found that prevalence of myopia in NHW children (1.20%) was the lowest among 4 racial/ethnic groups, including Asian (3.98%), Hispanic (3.7%), and black (6.6%; P < .0001 for all comparisons) children. Similarly, prevalence of astigmatism (?1.5 diopters) among NHW children was the lowest among 4 racial/ethnic groups, when compared with data from another MEPEDS paper.

Genes and Lifestyle

Genetics, as well as lifestyle and environmental factors, contribute to the differences among ethnic groups, the researchers note.

"A lot of children who have myopia have parents that have myopia, and the genetic predisposition is present to a significant extent in children of Asian descent," Rohit Varma, MD, professor and chair, Department of Ophthalmology, Illinois Eye and Ear Infirmary, University of Illinois at Chicago, and senior author of the article, told Medscape Medical News.

"In addition to that, it's thought that for children of Asian descent, their parents very early on begin to encourage activity similar to reading and doing near work," he continued. "The more time one spends doing near work early on, the higher the prevalence or rate of myopia. The eye just grows in a different manner when the child is doing a lot of near activities such as close-up computer games or reading or watching movies on iPads."

In contrast, studies have shown that NHW children who participate in a lot of outdoor activities, including viewing things at a distance, swimming, and participating in active sports, are less likely to become myopic, Dr. Varma said. That factor may also drive the difference in hyperopia, he added, with almost half as many Asian children having hyperopia. Astigmatism overlaps the 2 groups.

The new study "shows, in a way, what we already knew, that there are differences. I might say the differences are less than some people might have speculated," Michael X. Repka, MD, professor of ophthalmology and pediatrics at the Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, and coauthor of a similar study, commented in a telephone interview with Medscape Medical News.

Dr. Repka cautions against citing the "near theory," however, as the cause for this particular age group of 6 to 72 months. "The refractive error in this group is pretty minimal. For the hyperopia, that does not translate into 'these children need glasses.' That's the one caveat I would make here. For the farsighted patients, probably a very small portion of patients would need correction. Yes, the finding is there, but that finding of refractive error may not be pathologic in effect."

Applicable Across United States

Nevertheless, results of the latest study may be generalizable across the United States, the researchers note, because it is a population-based study. "The areas selected for doing this are similar in terms of sociodemographic and age distribution with the state of California and the United States," Dr. Varma said. "We had a participation rate of 80% to 87% who had an eye examination."

Dr. Repka agrees on the generalizability. "Population studies are not exciting because they don't tell people what to do, but they sure help ground development of practice guidelines of how to approach an individual when you have the background of this kind of number."

The authors have disclosed no relevant financial relationships.

Ophthalmology. Published online August 14, 2013.

    
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