Purpose: To explore the associations between macular choroidal and retinal thickness and axial elongation in non-myopic and myopic junior students.
Methods: In this school-based longitudinal observational study, axial length was measured by optical low-coherence reflectometry, and choroidal thickness and retinal thickness were measured by spectral-domain optical coherence tomography. Myopia was defined as non-cycloplegic objective spherical equivalent refraction ≤ -0.50 diopters. Structural equation modeling and multiple linear regression models were used to analyze the associations between baseline choroidal and retinal thickness with axial elongation.
Results: Out of 1307 students examined at baseline in 2017, 1197 (91.58%) returned for follow-up examination in 2018, with a median age of 12.00 years (interquartile range [IQR], 1.00) and included 667 boys (55.72%). Within a 1-year period, the median axial elongation of right eyes was 230 µm (IQR, 180) in boys and 200 µm (IQR, 160) in girls (P = 0.032). The thinner temporal choroidal thickness was associated with greater 1-year axial elongation only in myopic students (β, -0.20; 95% confidence interval [CI], -0.37, -0.03), the thinner temporal retinal thickness was associated with greater 1-year axial elongation in both non-myopic (β, -2.67; 95% CI, -4.52, -0.82) and myopic (β, -0.99; 95% CI, -1.68, -0.30) students, after adjustment for sex, age, and height. Subfoveal and nasal choroidal and retinal thickness were not significantly associated with axial elongation in either non-myopic or myopic students.
Conclusions: A thinner temporal choroid at age 12 years may predict greater 1-year axial elongation in myopic students, and a thinner temporal retina may predict greater 1-year axial elongation in both non-myopic and myopic students. This finding may help to identify children at risk and control axial elongation with potential preventive strategies.