Clinical

The Beijing Children Eye Study: A Rebound Effect?

By Nicole Xiao Liu, MOptom
PhD candidate, Brien Holden Vision Institute

Myopia, being the most frequent cause of distance visual impairment in the world, as well as a major risk factor for myopic macular degeneration, retinal detachment, and glaucoma, is projected to affect one in every two people by 2050[1, 2]. Over the past few decades, several extensive studies were conducted to explore the efficacy of various strategies to control myopia. Amongst these, outdoor exposure has been widely recognized as a preventive method against myopia onset[3]. However, the long-term outcome following treatment cessation was unknown, until The Beijing Children Eye Study[4].

In The Beijing Children Eye Study, outdoor intervention of 30-minutes jogging per school day was conducted in a rural Beijing primary school from 2012 to 2013 among 157 Grade 1&2 (Year 1&2) pupils. As a control, two-hundred-and-sixteen students from another school of similar socioeconomic status were selected. Detailed annual eye examination, including Lenstar biometry and non-cycloplegic auto- and subjective refraction was performed for both groups from 2012 to 2016.

Echoing the many previous observational and interventional study outcomes, this study identified lower myopia incidence in the outdoor group compared to the control (52.1% [95% CI: 43.8, 60.4] vs. 34.7% [95% CI: 25.0, 44.5]; OR: 0.49 (95% CI: 0.29, 0.84]; P = 0.01). In the meantime, a longer axial elongation was found associated with the control group versus study group (P = 0.005; b: 0.15; B: 0.05; 95% CI: 0.02, 0.09) after adjusting for female gender and longer axial length at baseline.

The real value of this study, however, lies in the follow-up findings after cessation of the outdoor intervention. The total incidences of myopia were not different after just one year of treatment cessation (43.2% vs. 43.7%; OR: 0.98; P = 1.0). During the first year after treatment cessation (from 2013 to 2014), the mean axial elongation in the intervention group was significantly higher compared to the control (0.27 ± 0.20 vs. 0.20 ± 0.15 mm; P = 0.001), as well as the mean refractive error changes (-0.32 ± 0.66 vs. -0.06 ± 0.66 dioptres; P < 0.001). By the end of the follow-up period (by 2016), mean annual axial length or refractive error changes between the two groups were indifferent (0.21 ± 0.23 vs. 0.23 ± 0.35 mm; P = 0.51; -0.27 ± 0.71 vs. -0.23 ± 0.68 dioptres; P = 0.56).

As elucidated by the authors, to sum up, for the first time, this study has potentially revealed ‘a complete rebound effect’ on myopia prevention with the use of outdoor intervention.

  1. Holden, B.A., et al., Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology, 2016. 123(5): p. 1036-42.
  2. Holden, B., et al., Myopia, an underrated global challenge to vision: where the current data takes us on myopia control. Eye (London, England), 2014. 28(2): p. 142-146.
  3. Xiong, S.Y., et al., Time spent in outdoor activities in relation to myopia prevention and control: a meta-analysis and systematic review. Acta Ophthalmologica, 2017. 95(6): p. 551-566.
  4. Guo, Y., et al., Outdoor Jogging and Myopia Progression in School Children From Rural Beijing: The Beijing Children Eye Study. Transl Vis Sci Technol, 2019. 8(3): p. 2.

 

Outdoor Jogging and Myopia Progression in School Children From Rural Beijing: The Beijing Children Eye Study

Guo Y, Liu L, Lv Y, Tang P, Feng Y, Wu M, Xu L, Jonas JB

Abstract

Purpose: To assess the influence of an outdoor program on myopia progression in school children.

Methods: The prospective interventional school-based study included 373 students aged 6 to 7 years (grade 1 or 2) who were examined annually between 2012 and 2016. Between 2012 and 2013, the children in the study group (n = 157) performed a 30-minute jogging exercise every school day, while the children in the control school (n = 216) did not. All children underwent a comprehensive ocular examination, including biometry.

Results: At 1 year after baseline, axial elongation and progression of myopic refractive error were significantly lower in the study group than in the control group. Study group and control group differed in axial elongation only in the subgroup of children nonmyopic at baseline, while axial elongation in the children myopic at baseline did not differ between both groups. At 1 and 2 years after the outdoor program stopped, increase in axial length was significantly larger in the study group. At 4 years after baseline, study group and control group did not differ significantly in total axial elongation and total change in refractive error.

Conclusions: An outdoor program of 30 minutes performed every school day for 1 year temporarily reduced myopia progression in schoolchildren nonmyopic at baseline, with a complete rebound effect after the program ended within the 3 following years.

Translational Relevance: An outdoor program of 30 minutes performed every school day for 1 year temporarily reduced the progression of myopia in schoolchildren nonmyopic at baseline for the period when the program was carried out.

Reference:

Guo, Y., Liu, L., Lv, Y., Tang, P., Feng, Y., Wu, M., … & Jonas, J. B. (2019). Outdoor Jogging and Myopia Progression in School Children From Rural Beijing: The Beijing Children Eye Study. Translational vision science & technology, 8(3), 2-2.

DOI: 10.1167/tvst.8.3.2

 

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