Myopia Research
Additional Articles
The Longitudinal Orthokeratology Research in Children (LORIC) in Hong Kong: A Pilot Study on Refractive Changes in Myopic Control
Author: Pauline Cho, Sin Wan Cheung, and Marion Edwards
Current Eye Research, 30: 71 ¨C 80, 2005
Purpose: Myopia is a common ocular disorder, and progression of myopia in children is of increasing concern. Modern overnight orthokeratology (ortho-k) is effective for myopic reduction and has been claimed to be effective in slowing the progression of myopia (myopic control) in children, although scientific evidence for this has been lacking. This 2 year pilot study was conducted to determine whether ortho-k can effectively reduce and control myopia in children.
Methods: We monitored the growth of axial lenth (AL) and vitreous chamber depth (VCD) in 35 children (7-12 years of age), undergoing ortho-k treatment and compared the rates of change with 35 children wearing single-vision spectacles from an earlier study (control). For the ortho-k subjects, we also determined the changes in corneal curvature and the relationships with changes of refractive errors, AL and VCD.
Results: The baseline
spherical equivalent refractive errors (SER), the AL, and VCD of the ortho-k
and control subjects were not statistically different. All the ortho-k subjects
found post-ortho-k unaided vision acceptable in the daytime. The residual SER
at the end of the study was −0.18 ?0.69 D (dioptre) and the reduction (less
myopic) in SER was 2.09 ?1.34 D (all values are mean ?SD). At the end
of 24 months, the increases in AL were 0.29 ?0.27 mm and 0.54 ?0.27 mm
for the ortho-k and control groups, respectively (unpaired t test; p = 0.012);
the increases in VCD were 0.23 ?0.25 mm and 0.48 ?0.26 mm for the
ortho-k and control groups, respectively (p = 0.005). There was significant
initial corneal flattening in the ortho-k group but no significant relationships
were found between changes in corneal power and changes in AL and VCD.
Conclusion: Ortho-k can have both a corrective and preventive/control effect in childhood myopia. However, there are substantial variations in changes in eye length among children and there is no way to predict the effect for individual subjects.
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Slowing Myopia Progression with Lenses
Corneal reshaping may be a future alternative for slowing myopia progression in children.
By Jeffrey J. Walline, OD, PhD
Every eyecare practitioner has had at least one parent ask with a desperate voice, "What can we do to keep my child from becoming as nearsighted as me?" Choosing new parents is obviously not an option. Short of that, there's little evidence of any treatment options that will significantly slow the progression of myopia in children.
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美國近視人口顯著增加
根據由美國國家衛生研究院（National Institute of Health, NIH）贊助， 近期在權威眼科雜誌，眼科學文獻 （Archives of Ophthalmology ）發表的 一項研究指出， 美國的近視發病率在過去的三十年間增加了66%， 從 1971-1972年間的25% 增加到1999-2004年間的 41.6% 。研究報告原文綜合如下：
美國最早的全國性近視發病調查報告在1971-1972 年間進行，包括5282名12到52歲的誌願者。調查以標準化方法檢查視力及驗光，采用右眼數據，結果顯示約25%的人為近視。此項1999-2004年間的研究包括12歲至54歲的誌願者共9609人。 經過視力及驗光檢查，采用右眼數據加以統計， 結果顯示近視者為 41.6% 與 1971-1972年間的結果相比較,其差別具有統計學意義。
該研究僅包括非西語(non-Hispanic)黑人和白人，沒有包括亞裔在內的其它族裔 。因此僅有8339人（86.8%）的資料進行了統計學分析處理。與三十年前的近視發病率相比，黑人至少增加一倍， 白人組根據不同年齡增加從30.3%-80.8%。 以性別分組分析， 男性與女性組均有顯著增加。具有高中以上文化程度者近視從25.7% 增加到59.8% 。
研究報告中提到近期內的數項研究結果，指出近視在年輕人群中，特別是在亞裔中大幅度增加。並認為與由於註重教育而增加近距離工作有關。
該項研究發表之後引起公眾關註。 美國廣播公司（ABC）報導研究結果，並 配合眼科界專家資訊。專家們認為近視增加的原因有遺傳因素，父母都近視的孩子容易患近視。 近距離工作如閱讀，電腦，手機電信等明顯增加是不可以忽略的因素。 近距離工作增加的同時，戶外活動減少是必然的結果，也是不利的因素。
目前美國國家衛生研究院（N I H）撥專款進一步研究近視發生的原因——近距離工作的具體影響，以圖將來有效防治。 專家們建議給孩子們做常規眼科檢查，早發現問題及時處理。 提倡增加戶外活動，培養孩子對運動的興趣。
筆者認為該報導證實近視的大幅度增加不限於亞裔。 希望主流社會引起重視，研究發病機制，提出進一步防治措施。美國廣播公司報導及研究文獻摘要鏈接網址如下：
http://www.youtube.com/watch?v=Vli0yA67lj0
http://archopht.ama-assn.org/cgi/content/abstract/127/12/1632