Percentile Charts for Normal Axial Length Changes in Chinese Schoolchildren with Stable Emmetropia

Abstract

Purpose : To describe the normal growth pattern of axial length (AL) with age in a cohort of schoolchildren with stable emmetropia.

Methods : Stable emmetropia was defined as spherical equivalent (measured by subjective refraction) > -0.5 D and ≤ +0.75 D in the right eye for 2 consecutive annual visits. A total of 700 schoolchildren with stable emmetropia enrolled in the Wenzhou Medical University-Essilor Progression and Onset of Myopia (WEPrOM) prospective cohort study, aged between 7 to 9 years with at least 2 years of follow-up between 2014 to 2018, were analysed. Ocular biometry, including AL measurements, was performed.

Results : A logistic function model was used to describe the changes in axial length with age, and a chart for AL changes versus age was plotted in percentiles (2.5th, 5th, 25th, 50th, 75th, 95th, and 97.5th; Figure). For children with stable emmetropia, the predicted change in AL in the next year was 0.22 (interquartile range [IQR; 25th to 75th percentile], 0.2-0.32) for children aged 7-9 years, 0.21 (0.13-0.3) for aged 10 years, 0.18 (0.08-0.27) for aged 11 years, and 0.12 (0.03-0.2) for aged 12 years. The lines with the predicted change in AL in the next year decreased gradually with age, till they plateaued nearing the age of 15 years, indicating that eyes of children with stable emmetropes continue to have AL growth till late adolescence.

Conclusions : Normal AL growth of approximately 0.2 mm/year (50th percentile) occurs among stable emmetropic Chinese schoolchildren aged 7-11 years. Percentile growth curves of changes in AL among stable emmetropes may be useful for clinicians to assess the effectiveness of myopia control interventions in slowing down axial elongation of myopic patients to that of a normal emmetrope.

This is a 2021 ARVO Annual Meeting abstract.