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Influence of Cycloplegia on Axial Length Prediction Models in a Paediatric Sample
Ivo Soares1,2,3, António Baptista4, Oscar Torrado5
1Department of Physics, University of Beira Interior, Covilhã, Portugal. isoares@ubi.pt.
Insights
Accurate axial length (AL) estimation is crucial for monitoring myopia in children. Cycloplegic measurements significantly improve the accuracy and repeatability of AL prediction models, making them a reliable alternative when optical biometers are unavailable.
Area of Science:
- Ophthalmology
- Pediatric Optometry
- Biometry
Background:
- Accurate axial length (AL) estimation is vital for monitoring myopia progression in children.
- Primary care settings often lack access to optical biometers, necessitating alternative methods for AL measurement.
- Prediction models utilizing cycloplegic measurements may offer a reliable solution for AL estimation in pediatric populations.
Purpose of the Study:
- To evaluate the impact of cycloplegia on the accuracy and repeatability of various AL prediction models in children.
- To identify which AL prediction models demonstrate minimal bias under both cycloplegic and non-cycloplegic conditions.
Main Methods:
- Ninety-six children (mean age 12.5 years) had repeated measurements of spherical equivalent refraction (SER), anterior corneal curvature (Kmean), and AL using the Myopia Master, pre- and post-cycloplegia.
- Seven published AL prediction models incorporating SER, Kmean, age, and sex were assessed.
- Performance and repeatability were evaluated using agreement, bias, limits of agreement (LoA), coefficient of repeatability (CoR), and intraclass correlation coefficient (ICC).
Main Results:
- Cycloplegia induced a hyperopic shift (+0.79 D) and improved the repeatability of measured AL (CoR decreased from ~0.14 mm to ~0.09 mm).
- All prediction models showed reduced bias post-cycloplegia, with mean differences ranging from -0.56 to +0.10 mm.
- Models by Morgan et al., Queirós et al., and Lingham et al. exhibited the smallest bias (<0.10 mm) and narrowest LoA (<0.84 mm).
- Spherical equivalent refraction variation accounted for 97-99% of predicted AL change; corneal curvature contributed ≤1.2%.
Conclusions:
- Cycloplegic refraction significantly enhances the accuracy and repeatability of AL prediction models in children.
- The prediction models developed by Morgan et al., Queirós et al., and Lingham et al. demonstrated superior performance.
- These predictive models, particularly with cycloplegic measurements, serve as a valuable alternative in settings lacking optical biometers.
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 with cycloplegic measurements 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 sample 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) underwent repeated measurements of spherical equivalent refraction (SER), anterior corneal curvature (Kmean) and AL, pre- and post-cycloplegia, using the Myopia Master. Seven published prediction models incorporating SER, Kmean, age and sex were evaluated. Agreement, bias, limits of agreement (LoA), coefficient of repeatability (CoR), 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 CoR decreased from ~0.14 mm to ~0.09 mm; ICC > 0.99). Pre-cycloplegia, models overestimated AL (mean differences from -0.87 to -0.24 mm); these biases were reduced post-cycloplegia (mean differences from -0.56 to +0.10 mm). Models by Morgan et al., Queirós et al. and Lingham had the smallest bias (<0.10 mm) and narrowest LoA (<0.84 mm). Variation in SER accounted for ~97-99% of the change in predicted AL, while the Kmean contributed ≤1.2%.
Conclusion:
Cycloplegic refraction significantly enhanced 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.
