Baseline factors associated with myopia progression and axial elongation over 30 months in children 5 to 12 years of age

Abstract

Purpose: This study aimed to identify baseline factors associated with greater myopia progression and axial elongation in children with myopia.

Methods: This study performed a post hoc analysis of data from a 30-month randomized trial of atropine 0.01% versus placebo in children 5 to <13 years old with baseline spherical equivalent refractive error (SER) of -1.00 to -6.00 D, astigmatism of ≤1.50 D, and anisometropia of <1.00 D SER. Data from atropine 0.01% and placebo groups were pooled given outcomes were similar. Baseline factors of age, SER, axial length, race, sex, parental myopia, and iris color were evaluated for association with changes in SER and with changes in axial length at 30 months (24 months on treatment and then 6 months off) using backward model selection.

Results: Among 187 randomized participants, 175 (94%) completed 30 months of follow-up. The mean change in SER was greater among younger children (-0.19 D per 1 year younger; 95% confidence interval [CI], -0.25 to -0.14 D; p<0.001) and children with higher myopia (-0.14 D per 1 D more myopia at baseline; 95% CI, -0.23 to -0.05 D; p=0.002). The mean change in axial length was also greater among younger children (0.13 mm per 1 year younger; 95% CI, 0.10 to 0.15 mm; p<0.001) and children with higher baseline myopia (0.04 mm per 1 D more myopia; 95% CI, 0.002 to 0.08; p=0.04).

Conclusions: Younger children with higher myopia had greater myopic progression and axial elongation over 30 months than older children with lower myopia. Developing effective treatments to slow the faster myopic progression in younger children should be a target of further research.

Trial registration: ClinicalTrials.gov NCT03334253.

Figure 1:. Adjusted Mean Change in Spherical Equivalent Refractive Error and Axial Length at 30 Months by Age and Baseline Spherical Equivalent Refractive Error

Mean change in spherical equivalent refractive error (A) and axial length (B) from baseline to 30 months adjusted for treatment group (A and B) and baseline axial length (B only). The subgroups were defined by dichotomizing age at enrollment and baseline spherical equivalent refractive error. Younger age was defined as 5 to <10.2 years and older age was defined as 10.2 to <13 years. Higher myopia was defined as −2.75 to −6.00 D and lower myopia was defined as −1.00 to myopia less than −2.75 D. The middle dot represents the mean and the error bars represent 95% confidence intervals. SER = spherical equivalent refractive error.

Figure 2:. Change in Spherical Equivalent Refractive Error and Axial Length at 30 Months by Age and Baseline Myopia

Scatterplots of change in spherical equivalent refractive error from baseline to 30 months (A, B) and change in axial length from baseline to 30 months (C, D) versus baseline spherical equivalent refractive error (A, C) and age at randomization (B, D). The line of best fit (least squares) is shown in blue and the Pearson correlation coefficient with 95% confidence interval is shown in red. SER = spherical equivalent refractive error.