Methodology

How MyopiaTracker Calculates Projections

Every number has a source. The projection engine is pure deterministic math — no black-box AI in core calculations. This page documents every formula, dataset, and efficacy value used.

Core Projection Formula

Axial length at age 18 is projected using observed growth rate and RCT-derived treatment efficacy:

AL_projected = AL_current + growth_rate × years_to_18 × (1 − tx_efficacy)

Where: growth_rate = ΔAL / interval (mm/year, from prior visit) tx_efficacy = RCT-derived reduction in axial elongation (0–1) years_to_18 = 18 − patient_age Confidence band = ±SD × √years_to_18

For first visits (no prior AL), the growth rate is estimated from population-average normative data for the patient's age and ethnicity.

Normative Growth Curve Datasets

Percentile rankings are calculated against the following peer-reviewed normative datasets, selected by ethnicity:

EthnicityDatasetn
European / White Tideman et al. 2016/2018 — JAMA Ophthalmol5,766
Multi-ethnic / Mixed Sanz Diez et al. 2019 — Ophthalmic Physiol Opt4,512
East Asian / South Asian He et al. 2015 — Ophthalmology (Shenzhen Myopia Study)1,892
Hispanic / Latino, African / Black Sanz Diez et al. 2019 (multi-ethnic subset)

Treatment Efficacy Values

All efficacy figures represent reduction in axial elongation vs untreated control at the primary RCT endpoint (~2 years). They are not cure rates or final AL targets.

TreatmentEfficacySource
Combination Therapy60–75% (modelled†) Multiplicative composite; capped at 75%
Stellest® (HALT lens)67%‡ Bao et al. 2022 — JAMA Ophthalmol
Atropine 0.05%58% Yam et al. 2019 (LAMP) — Ophthalmology
MiSight® 1 day55% Chamberlain 2019 — Optom Vis Sci
MiyoSmart® (DIMS)52% Lam CSY et al. 2020 — Lancet
Ortho-K50% Composite of multiple RCTs (Cho 2005, Santodomingo 2012)
Atropine 0.025%45% Yam et al. 2019 (LAMP) — Ophthalmology
Atropine 0.01%30% Chia et al. 2012 (ATOM2) — Ophthalmology
Outdoor / Behavioural18% Wu et al. 2013; He et al. 2015

‡ The 67% figure for Stellest® is from the full-time wearer subgroup (≥12 hrs/day wear compliance) in Bao et al. 2022. The intention-to-treat (ITT) population result is approximately 51%. MyopiaTracker uses 67% as the clinical target efficacy assuming full compliance, consistent with how the result is widely cited in clinical literature. Clinicians should counsel patients that real-world outcomes depend on wear hours. † Combination Therapy is a modelled composite (multiplicative formula, capped at 75%). No single RCT validates this figure directly. The range shown (60–75%) reflects model uncertainty; 68% is the midpoint used in projections. The proximity of the upper bound to Stellest® monotherapy (67%) reflects the mathematical ceiling of stacking high-efficacy treatments — at this efficacy level, combination adds marginal measurable benefit over high-efficacy monotherapy alone.

Composite Risk Score

The composite risk score is a clinical communication aid — not a validated diagnostic instrument. Weights are adapted from Tideman et al. 2018 risk model:

FactorWeight
AL percentile (vs age/ethnicity norms)30%
Growth velocity (mm/year)28%
Projected AL at age 1822%
Parental myopia (reported)12%
Near-work hours/day8%
⚠️ The composite score is a clinical communication aid, not a validated diagnostic instrument. Confidence intervals of ±5–10% apply. Population-average rates are used; individual biological variation is not accounted for.

Confidence Intervals

95% confidence bands on growth projections are calculated as:

CI = ±SD × √years_to_18

Where SD is drawn from the normative dataset for the patient's age and ethnicity group. Confidence intervals widen appropriately over longer projection horizons.

Limitations

Full Reference List

Tideman JWL et al. Association of Axial Length With Risk of Uncorrectable Visual Impairment for Europeans With Myopia. JAMA Ophthalmol. 2016;134(12):1355–1363.
Tideman JWL et al. Axial Length in Myopia: A Simple Predictor of Complications. Acta Ophthalmologica. 2018;96(3):301–309. doi:10.1111/aos.13603
Sanz Diez P et al. Growth curves of myopia-related parameters to clinically monitor the refractive development in children. Graefes Arch Clin Exp Ophthalmol. 2019. doi:10.1007/s00417-019-04290-6
He M et al. Onset and Progression of Myopia in School-Aged Children: The Shenzhen Myopia Study. JAMA Ophthalmology. 2015;133(7):768–775. doi:10.1016/j.ophtha.2015.02.022
Chamberlain P et al. A 3-year randomized clinical trial of MiSight lenses for myopia control. Optom Vis Sci. 2019;96(8):556–567. doi:10.1097/OPX.0000000000001410
Bao J et al. Spectacle Lenses With Aspherical Lenslets for Myopia Control vs Single-Vision Spectacle Lenses. JAMA Ophthalmol. 2022;140(5):472–478. doi:10.1001/jamaophthalmol.2022.0401
Yam JC et al. Low-Concentration Atropine for Myopia Progression (LAMP) Study. Ophthalmology. 2019;126(1):113–124. doi:10.1016/j.ophtha.2019.04.011
Chia A et al. Atropine for the Treatment of Childhood Myopia: Safety and Efficacy of 0.5%, 0.1%, and 0.01% Doses (ATOM2). Ophthalmology. 2012;119(2):347–354. doi:10.1016/j.ophtha.2011.07.031
Flitcroft DI. The complex interactions of retinal, optical and environmental factors in myopia aetiology. Prog Retin Eye Res. 2012;31(6):622–660. doi:10.1016/j.preteyeres.2012.06.004
Lam CSY et al. Defocus Incorporated Multiple Segments (DIMS) spectacle lenses slow myopia progression. Lancet. 2020;396(10240):74–79.