Changes in Ocular Biometrics of Non-Myopic High School Students: A Prospective Cohort Study on Myopia Risk Factors

Abstract Background. To characterize pre-myopia ocular biometric signatures and identify actionable early predictive biomarkers for myopia onset in non-myopic senior high school adolescents. Methods. This 30-month prospective cohort study enrolled 325 14–16-year-old students with baseline spherical equivalent refraction (SER) between 0 D and + 2.00 D. Comprehensive ophthalmic assessments including SER, axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT) were performed at baseline in September 2020, with follow-up evaluations scheduled at 15 and 30 months to track longitudinal changes in refractive status, biometric parameters, and new myopia incidence. Results. The 15-month cumulative new-onset myopia rate was 7.57%, rising to 16.84% at 30 months. Participants who later developed myopia (final SER ≤ −0.5 D) presented significantly lower baseline SER, longer AL, deeper ACD, higher AL/CR (corneal radius) ratio, and thinner LT than the non-myopic subgroups (all P < 0.05). This group also exhibited more rapid refractive deterioration and axial elongation across both follow-up visits. ROC analysis identified optimal baseline predictive thresholds for myopia onset: AL/CR at 2.99, ACD at 3.76 mm, and LT at 3.58 mm. Longitudinal cutoffs were also validated: 0–15 month AL elongation > 0.10 mm and AL/CR increment > 0.01, plus 15–30 month AL elongation > 0.07 mm and AL/CR increment > 0.01, all demonstrated strong predictive power. Conclusions. For adolescents approaching emmetropization stability, dynamic biometric shifts including accelerated axial elongation, anterior chamber deepening, lens thinning, and elevated AL/CR are robust early biomarkers for incident myopia, supporting targeted pre-myopia intervention.