Myopia Developing at Later Age May Exhibit Different Rate of Axial Length Growth

This chart from the study shows model-predicted annual change in AL (mm/year), stratified by the non-myopic group (blue) and incident myopia group: pre-myopia onset stage (green) and post-myopia onset stage (red). Solid curves represent predicted values from a generalized estimating equation model. Plotted points depict observed mean annual AL growth with standard error bars, calculated for each age within each refractive group. Photo: Liu WC, et al. Am J Ophthalmol. July 29, 2025. Click image to enlarge.  It’s definitional to the concept of myopia that kids who develop it experience greater axial length (AL) elongation. However, it has been less common in the literature to follow pediatric cases before they reach the myopia threshold, which is what a new study published in American Journal of Ophthalmology does.Characterizing the trajectories of AL growth in kids who developed myopia vs. those who remained non-myopic, researchers of the paper retrospectively collected and included data from 895 Chinese kids aged four to 15 at baseline; those included had non-myopic refractive error at baseline (SER >-0.50D) and were monitored for at least two years. Two groups were categorized: non-myopic, consisting of 541 children, and incident myopia, consisting of 354 children.After using a statistical model, researchers were able to determine from their data that significant differences existed in growth rates of axial length between the groups. In particular, kids in the post-myopia onset stage had faster AL growth than those in the pre-myopia onset stage or those who were non-myopic. What’s more, this difference was most pronounced in younger children, diminishing with age. AL growth post-myopia onset was faster than with pre-myopia onset growth up to age seven, while this was true in the non-myopic group up to age 10. An age-related decline in AL growth rate was seen in all groups, but the decline was most pronounced in kids belonging to the post-myopia onset stage, then the non-myopic group and finally the pre-myopia onset stage. Baseline axial length was also found to be associated with post-myopia onset growth rate, but the others were not. Interestingly, neither sex nor history of parental myopia were found to impact AL growth rate.Based on these findings, the authors of the study suggest in their paper that distinct growth phases may exist in relation to myopia development in children of different ages. This is further elucidated by the axial length growth rates. This rate after myopia onset was 0.43mm/year at age eight and decreased to 0.05mm/year by age 15 (difference of 0.38mm/year). However, in those who ended up non-myopic, AL growth rates decreased from 0.19mm/year at age eight to 0.06mm/year by age 15 (difference of 0.13mm/year), which is lower than the rates seen in incident myopia after onset.The investigators highlight the importance of their work in characterizing AL growth before myopia appears, too, with the pre-myopia onset stage culminating in growth rates of 0.27mm/year at age eight and 0.18mm/year at age 15 (difference of 0.09mm/year). Due to the slower age-related decline in growth before myopia onset, the authors relay that “preventive interventions should ideally be implemented before myopia onset in high-risk children, potentially during the period when eye growth begins to accelerate but before clinical myopia develops.”Click here for the journal source. Liu WC, Guo H, Lam CSY, et al. Axial length growth trajectories in children transitioning to myopia. Am J Ophthalmol. July 29, 2025. [Epub ahead of print].  This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.