ObjectiveTo observe and analyze the changes of macular choroidal thickness in children with occult high myopia and its influencing factors.MethodsA prospective, non-randomized, contemporaneous controlled trial. From September 2019 to October 2020, 56 children (110 eyes) who first visited the ophthalmic clinic of the Affiliated Hospital of Chengde Medical College without any myopia correction training were enrolled in this study. There were 33 males (64 eyes) and 23 females (46 eyes), with the average age of 8.62±1.87 years old; the age ranged from 6 to 12 years old. According to the clinical manifestations of myopia in children, they were divided into occult high myopia group (27 cases, 52 eyes) and control group (29 cases, 58 eyes). In the 52 eyes of the occult high myopia group, the spherical equivalent refraction (SER) of －0.00 to －1.00 D, ＞－1.00 to －2.00 D, ＞－2.00 to －3.00 D were 15, 16 and 21 eyes. Among 58 eyes in the control group, the SER of －0.00 to －1.00 D, ＞－1.00 to －2.00 D, ＞－2.00 to －3.00 D were 21, 18 and 19 eyes, respectively. The macular fovea within 6 mm was divided into three concentric circles centered on the macular fovea, which included the central area with a diameter of 1 mm, the inner ring area with a diameter of 1-3 mm, and the outer ring area with a diameter of 3-6 mm, totally 9 areas. The inner ring and outer ring were divided into upper, lower, nasal and temporal areas. The changes of choroidal thickness in each macular area of children in occult high myopia group and control group were observed. The choroidal thickness in each macular area was compared between the two groups using independent sample t-test. Pearson correlation analysis was used to analyze the correlation between mean foveal choroidal thickness and gender, age, intraocular pressure, ocular axis, diopter and corneal curvature in occult high myopia group.ResultsChoroidal thickness in macular area of children in occult high myopia group was thinnest in nasal side and thickest in temporal side. Compared with the control group, the mean choroidal thickness in the 9 macular zones of children in the occult high myopia group was significantly thinner than that in the control group, and the difference was statistically significant (P＜0.05). The mean choroidal thickness in each macular region decreased with the increase of diopter in children with occult high myopia. Compared with the control group with the same spherical equivalent, there was no significant difference in the area above the inner ring and the outer ring of the macular fovea in the occult high myopia group of －0.00 to －1.00 D and the temporal side of the inner ring and the outer ring of the macular fovea in the occult high myopia group of ＞－2.00 to －3.00 D (P＞0.05), but there were significant differences among the other regions (P＜0.05). Pearson correlation analysis results showed that the average choroidal thickness of the fovea in children with occult high myopia was negatively correlated with age (r=－3.410, R2=11.630, P=0.010), eye axis (r=1.420, R2=2.016, P=0.030) and diopter (r=－2.680, R2=7.182, P=0.040), but not significantly correlated with gender (r=0.166, R2=0.028, P=0.240), intraocular pressure (r=0.330, R2=0.109, P=0.800) and corneal curvature (r=－0.260, R2=0.068, P=0.850).ConclusionsThe thickness of macular choroidal in children with occult high myopia is the thinnest on the nasal side of the macular fovea and the thickest on the temporal side of the macular fovea. The mean choroidal thickness in each region of the macular is thinner than that in the common myopia children with the same diopter. The mean choroidal thickness of fovea is negatively correlated with age, ocular axis and diopter.