Purpose: We examined choroidal thickness (ChT) and its topographic variation across the posterior pole in myopic and nonmyopic children.
Methods: A total of 104 children aged 10 to 15 years (mean age, 13.1 ± 1.4 years) had ChT measured using enhanced depth imaging optical coherence tomography (OCT). Of these children 40 were myopic (mean spherical equivalent, -2.4 ± 1.5 diopters [D]) and 63 were nonmyopic (mean, +0.3 ± 0.3 D). Two series of 6 radial OCT line scans centered on the fovea were assessed for each child. Subfoveal ChT and ChT across a series of parafoveal zones over the central 6 mm of the posterior pole were determined through manual image segmentation.
Results: Subfoveal ChT was significantly thinner in myopes (mean, 303 ± 79 μm) compared to nonmyopes (mean, 359 ± 77 μm, P < 0.0001). Multiple regression analysis revealed refractive error (r = 0.39, P < 0.001) and age (r = 0.21, P = 0.02) were associated positively with subfoveal ChT. Also, ChT exhibited significant topographic variations, with the choroid being thicker in more central regions. The thinnest choroid was observed typically in nasal (mean, 286 ± 77 μm) and inferior-nasal (306 ± 79 μm) locations, and the thickest in superior (346 ± 79 μm) and superior-temporal (341 ± 74 μm) locations. The difference in ChT between myopic and nonmyopic children was significantly greater in central foveal regions compared to more peripheral regions (>3 mm diameter, P < 0.001).
Conclusions: Myopic children have significantly thinner choroids compared to nonmyopic children of similar age, particularly in central foveal regions. The magnitude of difference in choroidal thickness associated with myopia appears greater than would be predicted by a simple passive choroidal thinning with axial elongation.
Keywords: choroid; myopia; pediatric; refractive error.