Relationship Between the Axial Length to Corneal Radius of Curvature Ratio and Refractive Status in Young Malay Adults

Abstract

Background: Myopia is increasing worldwide and is closely linked to structural changes in the eye. While axial length and corneal radius are commonly measured in clinical practice, evaluating their relationship provides a more complete understanding of refractive status. The ratio between axial length (AL) and corneal radius (CR) reflects the balance between eye elongation and corneal shape. This study aimed to evaluate the relationship between the AL to CR ratio and spherical equivalent (SE) refraction in young Malay adults. Methods: A cross-sectional study was conducted involving 94 young Malay adults (86.2% female) aged between 20 and 30 years. Participants were included if they were emmetropic or myopic and had no history of ocular disease, surgery, or recent myopia control treatment. AL was measured using optical biometry, while CR was assessed using corneal topography. The AL to CR ratio was calculated by dividing AL by CR. Refractive error was determined through objective and subjective refraction, and spherical equivalent (SE) was calculated accordingly. Pearson correlation and linear regression analyses were used to examine the relationship between the AL to CR ratio and SE. Results: The mean SE was ?3.64 ± 2.35 dioptres, and the mean AL to CR ratio was 3.23 ± 0.16. A very strong negative correlation was found between the AL to CR ratio and SE (r=?0.902, p < 0.001). Linear regression analysis showed that the ratio explained 81.3% of the variation in refractive error (R²=0.813, p < 0.001), indicating that higher ratios were associated with greater levels of myopia. Conclusion: The AL to CR ratio is a reliable structural indicator of refractive status in young adults and shows strong potential in predicting myopia. These findings highlight its usefulness in clinical assessment and myopia management. These findings support the clinical utility of the AL/CR ratio as a robust biometric marker for identifying myopic risk, particularly in settings where cycloplegic refraction is unavailable.