Nasotemporal Asymmetry in Ocular Biometry as a Biomarker for Myopia Progression in Chinese Children.

PURPOSE: This multicentre longitudinal study investigated nasotemporal retinal asymmetry as a geometric biomarker for monitoring myopia risk in children.

METHOD: A total of 2520 Chinese children (Beijing cohort: N = 49, 5-14 years old; Anyang cohort: N = 2471, 6-9 years old) underwent annual measurements over 2 years, including axial length (AL), central spherical equivalent (CSE) and peripheral AL (30° nasal, temporal, superior, inferior) in the Beijing cohort and horizontal meridian peripheral refractions (±15°, ±30°) in the Anyang cohort. Retinal morphology was quantified through the vertex radius of curvature, asphericity and areas under the horizontal nasal and temporal retinal curve (AUHRCn and AUHRCt, respectively). Nasotemporal retinal asymmetry was defined as AUHRCt/n. Vertical asymmetry was defined as superior peripheral AL/inferior peripheral AL. Participants from the Anyang cohort were stratified into persistent myopia (myopic at baseline), newly developed myopia (myopia onset during follow-up) and persistent non-myopia (remained non-myopic over 2 years).

RESULT: In the Beijing cohort, the temporal-to-nasal AL ratio was the only factor significantly associated with myopic progression (ΔAL: r = -0.36, p = 0.01; ΔCSE: r = 0.37, p = 0.01). Validating this, in the Anyang cohort, decreasing AUHRCn preceded myopia onset, followed by progressive temporal steepening. Linear regression identified baseline AUHRCt/n as an independent negative predictor of myopic progression (β = 2.90, p = 0.03). A model incorporating baseline AUHRCt/n improved the prediction of progression risk (integrated discrimination improvement (IDI) = 3.74%, p = 0.03).

CONCLUSION

Progressive nasotemporal retinal asymmetry, particularly temporal steepening, precedes clinical myopia onset and was correlated with future refractive progression. This geometric biomarker shows potential for identifying myopic risk up to 2 years before manifest refraction changes, enabling earlier preventive interventions.