May 15, 2025
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The study, ‘The limitations of centile curves for evaluating myopic eye growth’ by Bullimore et al. (2025), critiques the utility of using centile (percentile) curves—similar to pediatric growth charts—to track myopia progression, specifically focusing on axial length (AL), a key marker of myopia progression. The goal of the study was to assess whether centile curves derived from mixed-population data can accurately reflect both normal and myopic eye growth, effectively track myopia progression, evaluate the success of interventions to slow progression and predict the onset of myopia.
The researchers compared six publicly available centile curve models across diverse populations (European, Indian and Chinese) against established longitudinal eye growth models. They analyzed how well these curves captured the trajectory of myopic axial elongation, both in existing and new-onset myopia.
The analysis showed that European-derived and Indian-derived curves generally match emmetropic growth at lower centiles but fail to capture the steeper progression seen in myopic eyes, even at higher centiles. On the other hand, Chinese-derived curves, influenced by a higher prevalence of myopia, approximated myopic growth more closely — but only in older children and at the highest percentiles. These findings suggest that centile curves often include a mix of refractive profiles, reducing their precision in tracking myopia progression.
May not accurately represent myopic eye growth
Based on the findings, centile growth curves underestimate axial elongation in myopic children because they combine data from both emmetropic and myopic eyes, flattening the curves and misrepresenting true myopic progression. Creating curves only for myopes is problematic, as newly diagnosed myopes with shorter axial lengths can skew percentile rankings. Additionally, the report found that centile curves track cumulative growth and are not sensitive to changes over time.
May not be the best tool to monitor myopia control treatment
One of the biggest takeaways from the study is that centile growth curves significantly underestimate axial elongation in myopic children, which limitis their usefulness in evaluating myopia control treatments. In clinical trials, treated children may appear to show little benefit when compared to these curves, despite clear reductions in eye growth. This is because the curves blend data from both emmetropic and myopic eyes, leading to misleading interpretations. As a result, treated children may still move to higher percentiles, which could falsely suggest inadequate treatment.
Do not accurately represent growth in incident myopia
Axial length growth in children follows three distinct patterns: persistent emmetropes, persistent myopes, and incident myopes who show accelerated axial elongation two to four years before myopia onset. This acceleration peaks around the time of onset and then slows by about 15% per year. The study showed that centile curves, which combine all eye types, fail to distinguish these differences and may obscure early signs of myopia development.
May not be the best way to predict myopia onset
While some propose using centile curves and axial length to predict myopia onset, the researchers reference previous studies that indicate cycloplegic refractive error remains the most reliable predictor. Axial length alone has limited predictive value, though the axial length-to-corneal radius ratio performs better. The researchers believe that tracking changes in axial length over time, such as rapid growth before onset, may help identify at-risk children—but it also requires consistent, annual measurements, which are not standard in clinical settings.
Limitations
The article acknowledges limitations in its analysis due to the lack of raw data and reliance on previously validated myopic and emmetropic eye growth models. While these models are broadly representative, factors like sex and baseline axial length may affect eye growth trajectories. For example, axial elongation tends to be faster in girls, and gender differences in myopia prevalence can skew centile curves. Additionally, higher initial axial length might correlate with slightly faster progression, complicating interpretation of centile trends.
Conclusions
This study shows that relying on centile position alone may mislead clinicians into underestimating disease progression. A more accurate approach that would best assimilate real-world scenarios would involve year-over-year absolute axial length changes compared to established growth norms, rather than percentile tracking.
Abstract
The Limitations of Centile Curves for Evaluating Myopic Eye Growth
Mark Bullimore, PhD, FAAO, Xu Cheng, MD, PhD, Noel A. Brennan, PhD, FAAO
SIGNIFICANCE
Pediatric growth charts are widely used to track height and weight. Recently, axial length growth charts have been developed. Unfortunately, they underestimate the rate of normal myopic eye growth, making it challenging to evaluate the benefits of myopia control interventions, due to the conflation of myopes and nonmyopes.
PURPOSE
The aim is to assess the value of axial length centile curves in the management of childhood myopia.
METHODS
Papers reporting centile curves were identified by searching PubMed. For comparison, axial length values for a representative selection of baseline values (21 to 24 mm at 6 years) were calculated as a function of age and ethnicity using published meta-analyses of myopic and emmetropic eye growth data.
RESULTS
Six published centile curves, largely based on cross-sectional data, were identified: three from European populations, two from China, and one from India. The trajectory of the emmetropic eye growth model generally tracks the European and Indian centile curves at lower centiles. This is not the case for the Chinese centile curves, likely due to the significant numbers of myopic children even at lower centiles. In contrast, the trajectory of the myopic eye growth model is steeper than that of the centile curves, even at higher centiles. This suggests that the higher centiles contain substantial numbers of nonmyopic children. Only in the centile curves for Chinese children, who have a higher prevalence of myopia, do they approach myopic eye growth, and then only for older children and at higher centiles.
Conclusions
Centile curves do not accurately represent myopic eye growth, are not the best tool to monitor myopia progression and treatment, do not accurately represent growth in incident myopes, and are not the best way to predict myopia onset. Separate centile curves for myopic eyes do not alleviate the problem because of incident myopia. Annualized growth models may provide a better approach to assessing axial elongation relative to population norms.
