Influence of cycloplegia on the axial length prediction models in a peadiatric cohort

Clinical Relevance Accurate axial length (AL) estimation is vital for monitoring myopia progression in children, especially in primary care where optical biometers are often unavailable. Prediction models adjusted for cycloplegic effects may offer a reliable alternative. Purpose To assess the effect of cycloplegia on the accuracy and repeatability of several AL prediction models in a paediatric cohort, and to identify which models maintain minimal bias under both cycloplegic and non-cycloplegic conditions. Methods Ninety-six children (mean age 12.5 ± 2.4 years-old) underwent repeated measurements pre- and post-cycloplegia of spherical equivalent (SE), anterior corneal curvature (Kmean), and AL using the Myopia Master. Seven published prediction models incorporating SE, Kmean, age, and sex were evaluated. Agreement, bias, limits of agreement (LoA), coefficient of repeatability (CR), intraclass correlation coefficient (ICC), and regression analyses were used to assess performance and repeatability. Results Cycloplegia induced a hyperopic shift (mean + 0.79 D), most pronounced in emmetropic and hyperopic eyes. Measured AL and all models showed improved repeatability post-cycloplegia (measured AL CR decreased from ~ 0.14 mm to ~ 0.09 mm; ICC > 0.99). Pre-cycloplegia, models overestimated AL (mean differences MD from − 0.87 to − 0.24 mm); these biases reduced post-cycloplegia (MD from − 0.56 to + 0.10 mm). Models by Morgan, Queirós, and Lingham had the smallest bias (< 0.10 mm) and narrowest LoA (< 0.84 mm). Variation in SE accounted for ~ 97–99% of change in predicted AL; Kmean contributed ≤ 1.2%. Conclusion Cycloplegic refraction significantly enhances both accuracy and repeatability of AL prediction models in children. Models by Morgan et al., Queirós et al., and Lingham et al. performed best. Predictive models may be a valuable substitute in settings without access to optical biometers, provided cycloplegic measurements are used when possible.