Why This Article Matters
While axial growth typically plateaus by adulthood, continued axial elongation has been reported in approximately 11.7% to 40% of adults with high myopia, exponentially increasing their lifetime risk for vision-threatening complications like myopic maculopathy and retinal detachment. Despite knowing several potential risk factors for this progression, clinicians have historically lacked robust, validated tools to predict an individual patient's risk of future axial elongation. This article is relevant to the myopia community right now because it addresses this gap by developing and internally validating a simple predictive model using routine parameters – specifically age and choroidal thickness (ChT) – to support individualized follow-up strategies.
Summary
This prospective cohort study (from the Wenzhou High Myopia Cohort) evaluated 1025 eyes of 532 adults (aged 18 to 60 years) with high myopia to identify optimal predictors for rapid axial elongation, defined as an increase of at least 0.10 mm over 2 years. The study found a mean annual axial elongation rate of 0.020 ± 0.051 mm/year, with 24.78% of the eyes developing rapid axial elongation.
Using bidirectional stepwise regression, the authors constructed a full predictive model (AUC = 0.811) including six variables: age, sex, axial length, best-corrected visual acuity, ChT, and choroidal vascularity index (CVI). Among the individual predictors, ChT showed the highest discriminative ability (AUC = 0.728), followed by age (AUC = 0.666). Younger age and female sex were independently associated with an increased risk of rapid axial elongation. A simplified model combining age and ChT achieved an AUC of 0.793, providing discrimination comparable to that of the full model while relying on only two routinely available clinical parameters. The authors additionally found a nonlinear relationship whereby thinner choroids were associated with faster axial elongation only below an age-dependent inflection point (e.g., 187 μm at age 20 versus 29 μm at age 60).
Commentary
Limitations
The study cohort predominantly consisted of individuals with relatively healthy fundi at the early stages of myopic maculopathy. Consequently, the generalizability of this predictive model to patients with advanced myopic macular degeneration remains uncertain. Additionally, the model has been internally validated but lacks external validation in independent cohorts. The study population was derived from a single Chinese cohort, which may limit generalizability to other ethnic populations.
Clinical relevance
This study provides clinicians with a simple risk-stratification model based on age and ChT that may help identify adults with high myopia at increased risk of future axial elongation. If externally validated, this approach could support individualized follow-up strategies and improve patient counselling. However, it should not yet be considered a tool for guiding therapeutic decisions.
Comparison with existing evidence
The study corroborates previous findings that younger age and female sex are independent risk factors for axial elongation in adults. However, it expands on this by quantifying the predictive dominance of ChT, supporting previous observations from experimental models and pediatric studies suggesting that reduced ChT is associated with ongoing ocular growth.
Unanswered questions
While the model effectively identifies adults at high risk for continued elongation, future longitudinal studies are needed to determine whether interventions aimed at slowing axial elongation in adults – including pharmacological, optical or surgical approaches – can modify disease progression in patients identified as high risk.
Key Take-Home Messages
- Axial elongation continues into adulthood for a significant portion of highly myopic patients, with nearly 25% demonstrating rapid elongation over a 2-year period.
- Age and choroidal thickness (ChT) are the most clinically practical predictors of future axial elongation in adults with high myopia.
- There is a nonlinear threshold effect regarding the choroid: a thinner choroid is associated with a faster rate of axial elongation, but only when the thickness falls below a certain inflection point.
- Age-specific ChT thresholds may facilitate individualized risk stratification, although external validation is still required before routine clinical implementation.
Conflict of Interest Statement
The author declares no conflict of interest related to this article.
Strengths
The primary strength of this study is its prospective design with a large sample size of highly myopic adults and the use of standardized protocols. The use of deep learningbased automated choroidal segmentation may improve measurement consistency.
Furthermore, the resulting simplified bivariate model (age and ChT) is transparent and clinically practical, relying on parameters that are routinely available with modern OCT imaging. Internal bootstrap validation and calibration analysis further strengthen the robustness and reliability of the proposed prediction model.