Longitudinal Changes in Choroidal Vascularity in Myopic and Non-Myopic Children

The purpose of this study was to evaluate longitudinal changes in choroidal vascular characteristics in childhood, and their relationship with eye growth and refractive error. Analysis of high-resolution optical coherence tomography (OCT) scans, collected over an 18-month period as part of the Role of Outdoor Activity in Myopia (ROAM) study, was conducted in 101 children (41 myopic, 60 non-myopic, age 10-15 years). OCT images were automatically analyzed and binarized using a deep learning software tool. The output was then used to compute changes in macular choroidal vascularity index (CVI), choroidal luminal, and stromal thickness over 18-months. Associations of these variables with refractive error and axial length were analyzed. CVI decreased significantly, whereas luminal and stromal thickness increased significantly over 18 months (all P < 0.001). The magnitude of change was approximately double in stromal tissue compared to luminal tissue (luminal β = 2.6 µm/year; 95% confidence interval [CI] = -1.0 to 4.1 µm/year; stromal β = 5.2 µm/year; 95% CI = 4.0, 6.5 µm/year). A significant interaction between baseline axial length and change in CVI over time (P = 0.047) was observed, with a greater CVI reduction in those with shorter axial lengths. Significant associations were observed between the change in CVI, luminal thickness, stromal thickness, and change in axial length over time (all P < 0.05). Faster axial eye growth was associated with smaller reductions in CVI, and less increase in choroidal luminal and stromal thickness. The changes in choroidal vascularity, particularly in the stromal component, may thus be a marker for eye growth. This knowledge of the longitudinal changes in choroidal vascularity in childhood and their relationship with eye growth may assist clinicians in the future to better predict eye growth and myopia progression in childhood.