September 1, 2025
By Kevin Chan, OD, MS, FAAO, IACMM
Photo Credit: Adobe Firefly
This article introduces an innovative method for assessing peripheral refraction using MRI ray tracing technology and explores its potential for predicting myopia progression. In recognition of the limitations of conventional optical techniques, Kneepkens et al. propose a novel imaging technique as a promising tool for research and clinical management of myopia.
Methodology
- The research utilizes magnetic resonance imaging (MRI) to visualize and quantify the shape and refractive profile of the eye, particularly focusing on peripheral areas often neglected by standard methods.
- A total of 1,635 subjects with varying degrees of myopia were recruited from the Generation R Study, a population-based birth cohort in Rotterdam, the Netherlands. The subjects underwent T2 weighted MRI scanning that generated high-resolution mapping of ocular anatomy and refraction.
- Horizontal and vertical peripheral refraction data points were analyzed at 50-degree eccentricity.
- Relative peripheral refraction (RPR) was derived from the difference between central cycloplegic refraction and peripheral refraction. Ordinal regression analyses were used to examine the effect of RPR on myopia progression quantile outcomes.
Key Findings
- Thirteen percent of children at 9 years of age had developed myopia.
- MRI revealed distinct patterns of peripheral refraction associated with different stages of myopia.
- Myopic children showed a significantly more hyperopic RPR compared to non-myopic and emmetropic children at all horizontal and vertical eccentricity.
- Each diopter increase in vertical RPR (OR: 1.10, CI: 1.01-1.20) and horizontal RPR (OR: 1.23, CI: 1.13-1.35) was associated with an increased risk of incident myopia.
- More rapid axial length progression was associated with higher horizontal RPR (OR: 1.16, CI: 1.10-1.22) and vertical RPR (OR: 1.08, CI: 1.02-1.14).
- The approach revealed the ability of detecting subtle changes in eye shape and peripheral optics, which precede clinical evidence of myopia progression.
- The study establishes correlations between MRI-derived peripheral refraction data and longitudinal changes in axial length and refractive error.
- Predictive models developed from this data may improve the ability to identify individuals at risk of rapid myopia progression.
Clinical Implications and Directions
With the result of significant variations shown in retinal curvatures among the subjects, the vast RPR differences for children with similar axial length and central spherical equivalent refractive errors suggest that current standard defocus strategies may not work for all individuals with various degrees of myopia.
The authors suggest that MRI-based assessment could enhance early diagnosis and intervention strategies for myopia. This would likely enhance personalized treatments and preventive measures. While this novel imaging technique is still in its infancy for practical application, it holds tremendous promise to help further our understanding of myopia mechanisms and improve patient outcomes.
Abstract
A Novel MRI-Based Approach to Peripheral Refraction and Prediction of Myopia Progression
Sander C.M. Kneepkens, Luc Van Vught, Jan Roelof Polling, Caroline C.W. Klaver, J. Willem L. Tideman, Jan-Willem M. Beenakker
Purpose
Optical solutions that create peripheral myopic defocus in the presence of a clear central image have shown to be effective as myopia treatment. This study investigates whether peripheral refraction measured via MRI and ray tracing can predict myopia progression in children.
Methods
A total of 1635 children from the Generation R Study, a population-based birth cohort in Rotterdam, the Netherlands, underwent T2 weighted MRI scanning at age 9 years. At both ages 9 and 14 years, ocular biometry, and cycloplegic autorefraction were assessed. Retinal curvature radii were computed from MRI segmentations using semi-automated, customized image processing algorithms. Individual peripheral refraction profiles were modelled through ray tracing. Horizontal and vertical peripheral refraction was analysed at 50-degrees eccentricity. Relative peripheral refraction (RPR) was calculated by subtracting peripheral refraction from central cycloplegic refraction. Yearly myopia progression was calculated and stratified into quantiles (∆AL), and the effect of RPR on the quantile outcomes was examined using ordinal regression analyses. Predictive performance of RPR on development of myopia was evaluated using ROC-analysis (fast vs slow progressors) and a logistic regression (incident myopia).
Results
At age 9 years, 207/1635 (13%) children had developed myopia. Myopic children had a significantly more hyperopic RPR compared to emmetropic children at all horizontal eccentricities (–1.8 ± 1.8D vs. 0.2 ± 2.1D) and vertical eccentricities (–1.0 ± 1.9D vs. 0.8 ± 2.2D). Higher vertical (OR: 1.08, CI: 1.02-1.14) and horizontal RPR (OR: 1.16, CI: 1.10-1.22) was associated with faster AL progression. Each diopter increase in vertical RPR (OR: 1.10, CI: 1.01-1.20) and horizontal RPR (OR: 1.23, CI: 1.13-1.35) was associated with an increased risk of incident myopia. ROC analysis indicated that RPR had a maximum predictive AUC of 0.77 for identifying fast progressors. Furthermore, MRI data revealed significant interindividual variations in retinal curvature (SD 1 mm), which resulted in clinically relevant peripheral refractive differences exceeding 8D among children with similar axial length and central SE, suggesting that standard defocus strategies may require individualization.
Conclusions
Using this novel approach to calculate peripheral refraction, we provide evidence based on eye shape that peripheral hyperopic refractive error is more pronounced in myopic children and is strongly associated with myopia progression. The significant anatomical variability in retinal radii underscores the need for personalized treatment strategies, which may enhance the efficacy of optical interventions for myopia management.
