Elsevier

Ophthalmology

Volume 126, Issue 1, January 2019, Pages 127-136
Ophthalmology

Original article
Environmental Risk Factors Can Reduce Axial Length Elongation and Myopia Incidence in 6- to 9-Year-Old Children

https://doi.org/10.1016/j.ophtha.2018.06.029Get rights and content

Purpose

To identify risk factors for axial length (AL) elongation and incident school myopia.

Design

Population-based prospective birth-cohort study.

Participants

Four thousand seven hundred thirty-four children examined at 6 and 9 years of age from the Generation R Study in Rotterdam, The Netherlands.

Methods

Axial length and corneal radius (CR) were measured with an IOLMaster 500 and daily life activities and demographic characteristics were obtained by questionnaire. Three thousand three hundred sixty-two children (71%) were eligible for cycloplegic refractive error measurements. Linear regression models on AL elongation were used to create a risk score based on the regression coefficients resulting from environmental and ocular factors. The predictive value of the prediction score for myopia (≤–0.5 diopter) was estimated using receiver operating characteristic curves. To test if regression coefficients differed for baseline AL-to-CR ratio, interaction terms were calculated with baseline AL-to-CR ratio and environmental factors.

Main Outcome Measures

Axial length elongation and incident myopia.

Results

From 6 to 9 years of age, average AL elongation was 0.21±0.009 mm/year and myopia developed in 223 of 2136 children (10.4%), leading to a myopia prevalence at 9 years of age of 12.0%. Seven parameters were associated independently (P < 0.05) with faster AL elongation: parental myopia, 1 or more books read per week, time spent reading, no participation in sports, non-European ethnicity, less time spent outdoors, and baseline AL-to-CR ratio. The discriminative accuracy for incident myopia based on these risk factors was 0.78. Axial length-to-CR ratio at baseline showed statistically significant interaction with number of books read per week (P < 0.01) and parental myopia (P < 0.01). Almost all predictors showed the highest association with AL elongation in the highest quartile of AL-to-CR ratio; incidental myopia in this group was 24% (124/513).

Conclusions

Determination of a risk score can help to identify school children at high risk of myopia. Our results suggest that behavioral changes can offer protection particularly in these children.

Section snippets

Methods

This study was embedded in the Generation R Study, a population-based prospective cohort study of pregnant women and their children in Rotterdam, The Netherlands. The complete methodology has been described elsewhere.23, 24 Briefly, 9778 pregnant women were included in the study, and children were born between April 2002 and January 2006. The children were invited at 6 and 9 years of age for examination at the research center. Of the initial cohort, 6690 children (68.4%) participated in the

General Characteristics

A total of 4734 children, 50.7% girls, underwent ocular biometry measurements at both 6.0±0.5 years of age and 9.8±0.3 years of age (Fig 1). Despite a difference in eye size, the increase in AL was not different between boys and girls (P = 0.95) and averaged 0.21 mm/year (SD, 0.09 mm/year). Children with myopia at the last visit demonstrated significantly greater axial elongation compared with nonmyopic participants (0.34 mm/year vs. 0.19 mm/year; P < 0.001).

Cycloplegic measurements of

Discussion

In this study, we identified ocular as well as environmental risk factors for axial eye growth. By combining these risk factors, we calculated a prediction score for myopia onset between 6 and 9 years of age and found a predictive value of 0.78. Axial length elongation had the highest predictive value for onset of myopia with an AUC of 0.85. Environmental factors were associated significantly with both increase in AL and incident myopia and had the greatest effect in children with the highest

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    Supplemental material available at www.aaojournal.org.

    Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

    The Generation R Study is supported by the Erasmus Medical Centre, Rotterdam, Erasmus University, Rotterdam, The Netherlands; the Netherlands Organisation of Scientific Research (NWO); Netherlands Organization for the Health Research and Development (ZonMw); the Ministry of Education, Culture and Science; the Ministry for Health, Welfare and Sports; the European Commission (DG XII); European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (grant 648268); the Netherlands Organisation for Scientific Research (NWO, grant 91815655); Uitzicht (grant 2013-24; Algemene Nederlandse Vereniging ter Voorkoming van Blindheid, Novartis Fund, Oogfonds, ODAS; Landelijke Stichting voor Blinden en Slechtzienden; MaculaFonds). The researchers are independent from the funders. The sponsor or funding organization had no role in the design or conduct of this research.

    HUMAN SUBJECTS: Human subjects were included in this study. The human ethics committees at Erasmus Medical Centre approved the study. All research adhered to the tenets of the Declaration of Helsinki. All participants provided informed consent.

    No animal subjects were included in this study.

    Author Contributions:

    Conception and design: Tideman, Polling, Jaddoe, Klaver

    Analysis and interpretation: Tideman, Klaver

    Data collection: Tideman, Polling, Klaver

    Obtained funding: Klaver

    Overall responsibility: Tideman, Polling, Jaddoe, Vingerling, Klaver

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