Changes in Choroidal Thickness of Healthy Children during Myopia Progression over 4 Years: Boramae Myopia Cohort Study Report 5

Objective: To investigate the relationship between choroidal thickness and myopia by analyzing change in choroidal thickness over time in children with myopia progression. Design: Retrospective cohort study. Participants: Children with myopia. Methods: Spherical equivalent (SE), axial length, and choroidal thickness were measured every 2 years during course of 4 years in children with myopia enrolled in a prospective cohort study. Choroidal thickness was evaluated at 13 points on the ETDRS grid, and its longitudinal changes as myopia progresses were analyzed. Patients were categorized into 2 subgroups: progression group (SE change ≤ −0.5 diopters [D] over 2 years) and stable group (SE change > −0.5 D over 2 years). Main Outcome Measures: Spherical equivalent of refractive errors, axial length, and choroidal thickness. Results: A total of 46 eyes from 23 participants were included, with a mean baseline age of 9.6 ± 1.7 years. The SE values at baseline, 2-year follow-up, and 4-year follow-up were −4.26 ± 2.34 D, −5.62 ± 2.45 D, and −8.67 ± 2.47 D, respectively, indicating an average myopia progression of 4.41 D over the 4-year period. During the initial 2 years, no significant thinning of choroidal thickness was observed at any of the 13 measured points. However, during the following 2 years, significant choroidal thinning was identified at 9 of the 13 points (P < 0.05). In the subgroup analysis of the subsequent 2 years, the progression group exhibited significant thinning at 8 points, while the stable group still showed no significant changes in choroidal thickness at any point. Conclusions: In the early phase of myopia progression within moderate degree, choroidal thickness remained unchanged. However, when progressed to high myopia, significant choroidal thinning occurred, specifically in the progression group. In contrast, the stable group maintained consistent choroidal thickness throughout the study. These results suggest that choroidal thinning in children varies according to the degree of myopia that develops. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.