Objective  To investigate the age-related changefor axial length (AL), Spherical equivalent (SE), prevalence of myopia and high myopiain children at 7 to 18 year-olds in Shanghai in 2014 and 2018, respectively, to compare these parameters between 2014 and 2018, and to evaluated the potential factors associated with AL.

Design An observational study.

Setting Jinshan Hospital of Fudan University in Shanghai.

Methods One primary school, one junior high school, and one senior high school were randomly selected in 2014 and 2018, respectively. AL, SE, prevalence of myopia and high myopia, height and weight were measured. A questionnaire regarding the lifestyles was completed.

Results Mean AL were shorter in 2018 than in 2014 (P = 0.003), whereas mean SE was greater in 2018 than in 2014 (P < 0.001). The prevalence of myopia and high myopia was lower in 2018 than in 2014 (P < 0.001 and P = 0.013, respectively). Mean AL increased with age from 7 year-oldsto18 year-oldsin 2014and 2018 (both P < 0.001), respectively. Mean SE decreased with age in 2014 and 2018 (both P < 0.001), respectively. The prevalence of myopia and high myopia increased with age in 2014 and 2018 (all P < 0.001), respectively. Multivariate regression analysis revealed that longer AL was mainly associated male gender and body height.

Conclusion This study shows normative growth values for AL and SE in Shanghai children at the age of 7 to 18 year-olds, as well as the age-specific prevalence of myopia and high myopia.