Ortho-K Lenses Slow Axial Length Elongation More in Children With High Myopia

A new real-world comparative study published in Eye and Vision reveals that orthokeratology lenses slow axial length elongation more effectively in children with high myopia, whereas spectacle lenses with highly aspheric lenslets perform better in younger children and those with mild myopia.

Comparative Effectiveness Across Refractive Categories

A retrospective study compared axial length elongation between orthokeratology, commonly known as ortho-K, and spectacle lenses featuring highly aspheric lenslets, referred to as HAL spectacles, in children with mild, moderate, and high myopia. The comparative efficacy of these treatments in controlling high myopia has remained insufficiently characterized in existing clinical evidence.

The study analyzed annual axial length elongation across different myopia levels to explore how relative treatment differences varied with baseline refractive error. Researchers determined that HAL lenses were associated with less axial length elongation in younger children and those with mild myopia. By contrast, ortho-K lenses demonstrated lower axial length elongation in children with high myopia. No significant differences between the two treatment modalities were observed in children with moderate myopia or among older children.

Propensity Score Matching and Subgroup Findings

The retrospective evaluation included children with a spherical equivalent refraction ranging from -0.50D to -9.00D.

After implementing propensity score matching to balance baseline characteristics, investigators evaluated 3,122 matched pairs representing 6,244 participants. Overall, the ortho-K cohort exhibited greater axial length elongation over a 12-month period compared to the HAL group, registering 0.20mm versus 0.15mm. In age-stratified breakdowns, the ortho-K group demonstrated greater elongation among children aged eight to nine years at 0.26mm compared to 0.19mm, and among those aged 10 to 11 years at 0.17mm compared to 0.12mm. No significant differences appeared in the 12-to-14 age bracket.

Potential Mechanisms and Peripheral Defocus Profiles

Researchers point to distinct optical properties to explain the observed refractive-error-dependent patterns. Ortho-K reshapes the cornea and may induce peripheral myopic defocus, whereas HAL spectacles provide a relatively fixed level of peripheral defocus. One possible explanation for the observed refractive-error-dependent pattern involves differences in these peripheral optical defocus profiles between the two intervention types.

“Age may influence the relative response to different optical interventions and underscores the importance of considering developmental stage when evaluating treatment outcomes.”

Researchers, Eye and Vision

The authors noted that younger eyes possess higher baseline growth rates and may exhibit greater responsiveness to specific optical signals. Meanwhile, the structural and optical changes tied to greater refractive correction can alter the distribution and magnitude of peripheral defocus in eyes with severe refractive error.

“Although this interpretation remains speculative, it highlights the importance of considering the combined effects of age and refractive status when evaluating AL elongation in children with myopia.”

Researchers, Eye and Vision

Machine Learning Models for Individualized Prediction

Parallel research published in the medical literature addresses the challenge of predicting individual treatment responses. This retrospective investigation utilized one-year follow-up data from 225 children treated with overnight orthokeratology to develop machine learning models capable of predicting individualized outcomes.

Ortho-K Lenses Slow Axial Length Elongation More in Children With High Myopia — Photo: Reviewofoptometry

Using random sampling, investigators divided 225 samples into a training set of 180 and a test set of 45. LASSO regression identified five key features—age, diopter, flat keratometry, 6mm corneal higher-order aberrations, and 6mm intraocular trefoil—to construct predictive algorithms. Among evaluated architectures including K-Nearest Neighbors, Support Vector Machines, Random Forest, Extra Trees, and XGBoost, Support Vector Machines demonstrated the highest predictive quality, achieving an area under the curve of 0.877 in the training set and 0.828 in the external validation set.

Clinical Implications for Pediatric Myopia Management

The findings emphasize that low myopia serves as the primary modifiable risk factor for pathological myopia, which carries severe complications including glaucoma, myopic macular degeneration, and optic neuropathy. While orthokeratology and HAL spectacles offer noninvasive avenues for intervention, significant differences in myopia control efficacy persist among individual patients due to a historical lack of personalized lens design.

Can Ortho-K Overnight Contacts Slow Myopia?

The integration of machine learning tools utilizing accessible clinical and corneal topography features provides ophthalmologists with cost-effective strategies to anticipate patient-specific responses. These computational models, alongside comparative data distinguishing the efficacy of ortho-K in high myopia from HAL lenses in milder cases, supply clinicians with evidence to refine treatment selection and adjust intervention methods as children develop.