December 2, 2024
By Liesl Forward, BSc, OD
Photo Credit: Getty Images
Ethnicity is a key demographic detail for clinicians and researchers interested in refractive error, as it has been found to influence myopia development. Therefore, robust data for refractive error and axial length by ethnicity, location, and age is needed.
Naduvilath et al. (2024) have aimed to deepen understanding of expected axial length and refractive error change in East Asian and European children aged 6-16.9 years. To do this, they chose to favor raw population-based data over that from clinical trials to avoid selection bias. They also considered the effect of differential urbanization by region and accounted for this in their statistical model.
East Asian children were found to have higher progression rates for both axial length and refractive error than European children. For example, a six-year-old myopic child had an axial length progression of 0.58mm a year if they were East Asian, but 0.43mm if they were European. However, this difference was most marked at younger ages, and by age 13-14, it became clinically insignificant. The difference was greatest in myopes, though it was still present in non-myopes.
The authors discuss that ethnicity is a complex factor comprised of both genetics and environment and ethnic differences may not be as great if the environment is shared (i.e., East Asian and European children in the same city may not differ quite as much). However, clinicians should still find the data valuable to integrate into practice.
Abstract
Regional/Ethnic Differences in Ocular Axial Elongation and Refractive Error Progression in Myopic and Non-Myopic Children
Naduvilath, T., He, X., Saunders, K., Demir, P., Leighton, R., McCullough, S., Tran, H., Ha, T., Macedo, A. F., Xun, X., Sankaridurg, P., & Tahhan, N.
Purpose: To determine the regional and ethnic differences in ocular axial elongation and refractive error progression in myopic and non-myopic children.
Methods: A retrospective analysis of 15 longitudinal clinical and population-based studies was conducted in the UK, Sweden, Australia (classified as European), China, and Vietnam (classified as East Asian) between 2005 and 2021. A total of 14,593 data points from 6208 participants aged 6–16 years with spherical equivalent from +6 to −6 D were analysed. Progression was annualised from longitudinal axial length and cycloplegic spherical equivalent (SE) refraction. Generalised estimating equation models including main effects and interactions were used for model building. Age and region-specific estimates for myopes and non-myopes and confidence intervals are reported.
Results: Factors affecting axial elongation and SE progression in children included being myopic, followed by age, region/ethnicity, and sex. The magnitude of regional/ethnic differences was dependent on myopia and age. Axial elongation and SE progression were lower in European compared with East Asian children, but differences were reduced with increasing age and differences in axial elongation larger in myopes than non-myopes. Age-specific regional/ethnic differences indicated that axial elongation for a 6-year-old East Asian myopic child was greater than a European child by 0.15 mm/year (0.58 vs. 0.43 mm/year) and by 0.09 mm/year (0.35 vs. 0.26 mm/year) for a 10-year-old myope. SE progression was lower in a 6-year-old European myope by 0.48 D/year and at 10 years of age by 0.34 D/year compared with an East Asian myope.
Conclusions: There are regional/ethnic differences in age-specific refractive and axial growth patterns in both myopic and non-myopic eyes, with more marked differences in younger East Asian children who demonstrated a higher axial growth and greater negative SE shift than their non-Asian peers. Regional/ethnic differences in progression reflect environmental and ethnic variations. Age and region/ethnicity-specific estimates could contribute as a reference for future comparisons.
Naduvilath, T., He, X., Saunders, K., Demir, P., Leighton, R., McCullough, S., … & Tahhan, N. (2024). Regional/ethnic differences in ocular axial elongation and refractive error progression in myopic and non‐myopic children. Ophthalmic and Physiological Optics. Advance online publication.
DOI:https://doi.org/10.1111/opo.13401
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Dr. Liesl Forward is an Australian clinical optometrist who graduated from the University of Melbourne. After working in regional private practice, she now works for the Australian College of Optometry in Melbourne. She is strongly interested in ocular disease management and public health and is also involved in clinical teaching and outreach eye care. |
