Rapid Axial Elongation Progression Associated with Poorer Visual Outcomes

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A new study identified three distinct axial elongation trajectories from childhood to late adulthood, from stable to moderate to rapid progression, and their association with visual outcomes among nearly 800 patients in China with high myopia.¹

Across 8 years of follow-up, the study found rapid progression of axial elongation was associated with a nearly 7 times greater risk of developing pathological myopic macular degeneration, as well as poorer best-corrected visual acuity, compared with stable progression trajectories.

“These distinct axial elongation trajectories could prove valuable for early identification and intervention for high-risk individuals,” wrote the investigative team, led by Xiaotong Han, MD, PhD of the Zhongshan Ophthalmic Center at Sun Yat-sen University and Mingguang He, MD, PhD, of the school of optometry at The Hong Kong Polytechnic University.¹

High myopia often stems from excessive axial elongation and is associated with an increased risk of visually threatening ocular pathology. Unlike mild or moderate myopia, high myopia progression has been found to continue into adulthood.

As a result, long-term follow-up is necessary to understand axial length changes in those with high myopia – however, current knowledge regarding these trajectories is limited due to small sample sizes and insufficient follow-up. Han and colleagues indicated the ability to determine if high myopia will remain stable or continue to rapidly progress has important implications for clinical management in eye care.

The study included patients recruited between November 2011 and October 2012 in the ongoing Zhongshan Ophthalmic Center-Brien Holden Vision Institute Cohort Study of high myopia. A total of 890 patients with high myopia (spherical power ≤−6.00 diopters), including axial length measurements at baseline and ≥1 follow-up visit, were included for analysis. Data were analyzed from November 2022 to June 2023.

Investigators used cluster analysis to identify different axial elongation trajectories and associated visual outcomes. The team categorized individuals in the analysis by baseline age as children and adolescents (7 to <18 years), young adults (18 to <40 years), and older adults (≥40 to 70 years).

Overall, 793 participants (median age, 17.8 years; 418 female patients [52.7%]), or 1586 eyes, matched the inclusion criteria and were included for analysis. Analyses showed the mean axial elongation rates were 0.46 mm/y (95% CI, 0.44 - 0.48) for children and adolescents, 0.07 mm/y (95% CI, 0.06 - 0.09) for young adults, and 0.13 mm/y (95% CI, 0.07 - 0.19) for older adults.

A total of 469 eyes from 240 participants were included in the cluster analysis. Cluster analysis revealed 3 axial elongation trajectories, with mean axial elongation trajectories of 0.02 (95% CI, 0.01 to 0.02), 0.12 (95% CI, 0.11 to 0.13), and 0.38 (95% CI, 0.35 to 0.42) mm/y in the stable, moderate, and rapid progression trajectories, respectively.

At the 8-year follow-up, individuals in the rapid progression trajectory experienced a 6.92 times higher risk of developing pathological myopia macular degeneration (odds ratio [OR], 6.92; 95% CI, 1.07 to 44.60; P = .04), compared with the stable progression cohort. Participants in the rapid progression trajectory also exhibited a decrease of 0.032 logMAR in BCVA (β, 0.032; 95% CI, 0.001 - 0.063; P = .04) at the end of the 8-year follow-up, compared with the stable progression cohort.

In an invited commentary, David A. Mackey, MD, of the center for ophthalmology and visual science in the Lions Eye Institute at The University of Western Australia indicated monitoring axial elongation trajectory may help identify individuals at high risk of pathological myopia.²

Mackey noted clinicians should be able to identify children at risk of myopia and its progression, compared with those with normal axial growth, and work to implement treatment if there is evidence a child would benefit from therapy.

“As ophthalmic epidemiologists, we should aim to develop a normative reference for axial length and its trajectory, as well as develop interventions to slow the progression of myopia in the high-risk groups,” Mackey wrote.²

References

1. _{Zhang S, Chen Y, Li Z, et al. Axial Elongation Trajectories in Chinese Children and Adults With High Myopia. JAMA Ophthalmol. Published online December 28, 2023. doi:10.1001/jamaophthalmol.2023.5835}
2. _{Mackey DA, Lee SS. Emerging Role of Axial Length Trajectories in the Management of Myopia. JAMA Ophthalmol. Published online December 28, 2023. doi:10.1001/jamaophthalmol.2023.6087}