To evaluate the distribution characteristics of choroidal vascularity index (CVI) in macula among normal children using swept-source optical coherence tomography (SS-OCT), and to investigate the influencing factors.

A cross-sectional study was conducted.Sixty-three children aged 6 to 12 years were enrolled in The First Affiliated Hospital of Zhengzhou University from May 2021 to November 2021.Spherical equivalent refraction, axial length (AL) and other ocular biological parameters were measured.Macula-centered CVI and choroidal thickness (ChT) were measured by SS-OCT angiography.According to the ETDRS partition, the obtained image was divided into macular central fovea (0-1 mm diameter), inner ring (1-3 mm diameter) and outer ring (3-6 mm diameter) zones.Data from the right eye were selected for statistical analysis.CVI in the three rings and four zones (superior, temporal, inferior and nasal zones) of the inner and outer rings were compared.Univariate and multiple linear regression analyses were used to analyze the correlation between CVI and sex, AL, anterior chamber depth (ACD), ChT and pupil diameter.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of The First Affiliated Hospital of Zhengzhou University (No.2021-KY-0399-003). Written informed consent was obtained from each guardian.

The average CVI in the macular central fovea, inner ring and outer ring were 0.35±0.12, 0.32±0.10 and 0.27±0.08, respectively, with a significant difference (F=10.96, P<0.001), and significant differences in CVI were found in pairwise comparisons of the three ring zones (all at P<0.05). Significant differences in CVI were found among superior, temporal, inferior and nasal zones in inner and outer rings (F_ring=11.60, P=0.001; F_zone=12.02, P<0.05). The CVI was smaller in superior and nasal zones in inner ring than in temporal zone, greater in superior, temporal and inferior zones in outer ring than in nasal zone, smaller in superior zone of outer ring than that of the inner ring, and the differences were statistically significant (all at P<0.001). The single factor linear regression analysis showed that ChT in the fovea, inner ring and outer ring were the influencing factors of CVI in the three ring zones (all at β=0.001, P<0.001). Pupil diameter (β=0.034, P=0.038; β=0.040, P=0.003; β=0.024, P=0.011) and ACD (β=0.097, P=0.034; β=0.097, P=0.013; β=0.061, P=0.032) were the influencing factors of CVI in fovea, inner ring and outer ring.After multiple linear regression analysis, the regression equations were established as follows: CVI in the macular fovea=0.001×ChT in the macular fovea + 0.001×ChT in the inner ring+ 0.001×ChT in the outer ring-0.301 (R²=0.514, F=6.875, P<0.001); CVI in the inner ring=0.001×ChT in the macular fovea+ 0.001×ChT in the inner ring+ 0.001×ChT in the outer ring+ 0.088×AL-0.307 (R²=0.603, F=9.870, P<0.001); CVI in the outer ring=0.001×ChT in the macular fovea+ 0.001×ChT in the inner ring+ 0.001×ChT in the outer ring-0.135 (R²=0.601, F=9.781, P<0.001).

In children aged 6-12 years old, the CVI is higher in the macular central fovea than in inner and outer rings, and the CVI in nasal zone is the smallest in both inner and outer rings.The thicker the ChT, the higher the CVI in all zones in the macular area; the deeper the anterior chamber, the higher the CVI in the inner ring.

Choroid; Child; Reference values; Choroidal vascularity index; Swept-source optical coherence tomography; Related factors; Myopia; Choroid diseases