CRAI: Cumulative Relative Asymmetry Index — analytical dataset and code for quantifying interocular asymmetry of axial elongation in paediatric myopia

This deposit accompanies a methodological study introducing and validating the Cumulative Relative Asymmetry Index (CRAI) — a novel scale-invariant metric for quantifying interocular asymmetry of axial elongation in paediatric myopia. The metric is defined at the interval level (Relative Asymmetry Index, RAI) and aggregated at the patient level (CRAI), complemented by an annualised Absolute Asymmetry Index (AAI). The deposit contains the anonymised patient-level dataset (n = 256 children, ages 5–16 years, 904 follow-up intervals), the Python reference implementation of the metrics, and a complete analysis pipeline reproducing the principal numerical findings. Data collection: clinical records were collected during routine ophthalmological care between approximately 2015 and 2026 in Barnaul, Russian Federation, and aggregated into a centralised digital monitoring platform during 2025–2026 for the present analysis. Key findings reproducible from this deposit:- Median CRAI 22.8%, median annualised AAI 0.074 mm/year- Approximately 70% of patients exhibit detectable asymmetry (CRAI > 15%)- Pronounced asymmetry (CRAI > 50%) affects 14.1% of the cohort, with the slower-progressing eye accumulating axial length at no more than half the rate of the faster-progressing eye- 22% of the cohort exceeds the MDC₉₅ threshold (0.118 mm/year) at the individual level- Age-related rise of CRAI from 19% to 44% alongside falling overall progression rate, consistent with a two-component model of axial elongation Version 2.0 (May 2026): Revised principal category cut-offs from 15/45% to 15/50% on principled grounds — 15% serves as a statistical noise filter while 50% has a direct biological interpretation. Dataset and metric definitions are unchanged from Version 1.0; only default category thresholds in the code have been updated. Interval-level data are not deposited to minimise re-identification risk but are available from the corresponding author upon reasonable request.