Purpose: To elucidate the trajectory of axial length growth in schoolchildren through an observational study conducted over a period of up to 9 years in public elementary and junior high schools in Kyoto Prefecture.
Methods: This study included 1960 eyes from 981 students who underwent measurements of subjective refraction under non-accommodation paralysis and non-contact axial length once a year from 2013 to 2022. Percentile curves of axial length were determined separately for males and females as descriptive statistics. For eyes with refraction and uncorrected visual acuity, we classified them as emmetropia, myopia, and hyperopia to create predictive curves for the amount of axial length elongation.
Results: Percentile curves revealed an increase in axial length and proportion of myopia with increasing grade. The 50th percentile values at the first grade were 23.0 mm for males and 22.4 mm for females, which were higher than those reported for Western populations. Increases in the amount of axial length elongation were larger in lower grades, myopia, and females, and showed a correlation with the number of parents wearing glasses or contact lenses. The rate of the amount of axial length elongation in myopia decreased over time, and by the 9th grade (15 years old), the differences in the amount of axial length elongation between emmetropia, myopia, and hyperopia had diminished.
Conclusions: The amount of axial length elongation in myopic eyes is greater in the lower grades and decreases with growth. Thus, when using axial length for follow-up of myopia progression treatment, referring to the average progression can enable a more accurate assessment.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 129: 817-825, 2025.