Risk factors for myopia progression in second-grade primary school children in Taipei: a population-based cohort study

Purpose To evaluate the 1-year progression of myopia and associated risk factors in second-grade primary school children. Methods The myopia investigation study in Taipei provided semiannual visual acuity testing and cycloplegic refraction for all second-grade primary school children (mean age: 7.49 years) in Taipei who provided parental consent. A questionnaire was distributed to the participants' parents before the first and third examinations. We evaluated 1-year follow-up data for children noted to have myopia on the first examination. Multinomial logistic regression models were applied to assess risk factors associated with myopia progression. Myopia progression was categorised, based on the change in spherical equivalent (Delta SE) over 1 year, as slow (Delta SE>-0.5 dioptres (D)), moderate (-1.0 D<Delta SE <=-0.5 D) or fast (Delta SE <=-1.0 D). Of the 4214 myopic children, data were analysed for 3256 (77.3%) who completed the 1-year follow-up evaluation. Results The baseline SE was -1.43+/-1.1 D. The average Delta SE was -0.42+/-0.85 D, with 46.96%, 28.50% and 24.54% of the study subjects showing slow, moderate and fast myopia progression, respectively. When compared with slow myopia progression, fast myopia progression was associated with a greater myopic SE at baseline (OR: 0.67, 95% CI: 0.61 to 0.72) and a shorter eye-object distance when doing near work (OR: 1.45, 95% CI: 1.18 to 1.78). More outdoor activity time and self-reported cycloplegic treatment were not associated with slow myopia progression. Conclusions Children with fast annual myopia progression were more myopic at baseline and had a shorter reading distance. Our study results highlight the importance of having children keep a proper reading distance.