Variations in physiological and myopic eye growth among children from different populations

To evaluate physiological and myopic eye growth among children in Wenzhou, China, in comparison to other populations. Prospective observational cohort study. Physiological and myopic eye growth were examined using data from 700 non-myopic (spherical equivalent [SE] > -0.5 diopters [D] for at least 2 years) and 297 myopic (SE ≤ -0.5 D) schoolchildren, respectively, aged 7 to 9 years at baseline from the Wenzhou Medical University-Essilor Progression and Onset of Myopia (WEPrOM) cohort study in Wenzhou, China, with a follow-up of 4.5 years. Logistic function models were used to describe eye growth with age. Axial length (AL) measurements were used to compute eye growth, and compared with physiological and myopic eye growth data from the following studies: Orinda Longitudinal Study of Myopia (OLSM), Singapore Cohort Study of the Risk Factors for Myopia (SCORM), and retrospective analysis of eight studies in Guangzhou and Shanghai. In children aged 7, 8, 9, 10, 11, and 12 years in the WEPrOM study, the predicted physiological eye growth was 0.22, 0.22, 0.22, 0.21, 0.19, and 0.12 mm/year, and the predicted myopic eye growth was 0.52, 0.50, 0.47, 0.43, 0.36, and 0.27 mm/year (50th percentile), respectively. Compared to other populations, in children aged 8 to 12 years, physiological eye growth in the WEPrOM study (0.22 to 0.12 mm/year) was comparable with that of the retrospective analysis in China (0.27 to 0.15 mm/year), but was greater than that of SCORM (0.12 to 0.04 mm/year) and OLSM (0.15 to 0.06 mm/year). In children aged 8 to 12 years, myopic eye growth in the WEPrOM study (0.5 to 0.27 mm/year) was comparable with that of the retrospective analysis in China (0.46 to 0.26 mm/year), but was greater than that of SCORM (0.44 to 0.16 mm/year) and OLSM (0.28 to 0.20 mm/year). Physiological and myopic eye growth likely differ between populations of varying ethnicities and countries. Therefore, it is important to apply physiological eye growth rates from a similar source population in interpretation of myopia control efficacy outcomes related to axial elongation.