ObjectiveTo observe and analyze the changes of macular retinal thickness and related factors in children with occult myopia. MethodsA prospective longitudinal control study. From February 2021 to February 2022, 120 eyes of 60 children who first visited Department of Ophthalmology of The Affiliated Hospital of Chengde Medical College without any corresponding myopia correction treatment were included in the study. There were 32 males (64 eyes) and 28 females (56 eyes), with the age of 4-6 years. Visual acuity, medical optometry, corneal topography, spectral-domain optical coherence tomography (OCT) and axial length (AL) were measured at the first visit and 3, 6, 9 and 12 months. The children were divided into occult myopia group with 60 eyes of 30 cases and control group with 60 eyes of 30 cases according to visual acuity, equivalent spherical refraction (SE), AL and corneal curvature (CC). The macular fovea retinal thickness was measured by spectral-domain OCT enhanced deep imaging technique. According to the treatment and study of diabetic retinopathy, the retina within the 6 mm of the macular center was divided into three concentric circles with the macular fovea as the center, the central fovea of 1 mm, the inner ring of 1-3 mm and the outer ring of 3-6 mm. In the inner ring and outer ring, the retina was divided into 4 areas, upper and lower, left and right, with a total of 9 regions. The four regions of the inner ring and the outer ring were superior, inferior, nasal and temporal, respectively. The differences of AL, CC, SE, macular retinal thickness and the changes of related factors with time were compared between the occult myopia group and the control group. SE, AL, CC and retinal thickness in different macular regions of the two groups were compared by repeated measurement analysis of variance. In pairwise comparison, the minimum significant difference t test was used in different measurement time points, and the independent sample t test was used between groups at the same measurement time points. ResultsAt first diagnosis and after diagnosis, there were significant differences in SE (F=783.710), AL (F=742.192), macular fovea (F=330.292), inferior and temporal (F=158.250, 108.292) side of the outer ring retinal thickness in occult myopia group (P＜0.01). In the control group, there were significant differences in the retinal thickness of SE (F=1 793.976), AL (F=457.362), macular fovea (F=31.029), inferior and temporal (F=7.405, 77.245) side of the outer ring retinal thickness (P＜0.01). In both groups, with the prolongation of the time after the first diagnosis, the SE gradually increased, the AL gradually lengthened, and the thickness of the macular fovea, inferior and temporal side of the outer ring retinal thickness gradually thinned. Independent sample t test was performed on the data with differences between groups at the same time, and the results showed that at 3, 6, 9 and 12 months after first diagnosis, there were significant differences in SE, AL and CC between the occult myopia group and the control group (t=－4.801,－11.532, 16.276,－17.145), AL (t=24.203, 26.353, 27.057, 25.552); CC (t=－23.362,－25.382,－25.890,－24.350; P＜0.01). There were significant differences in macular fovea, inferior and temporal side of the outer ring retinal thickness at 6, 9 and 12 months, macular fovea (t=－2.596,－2.542, －2.941; P＜0.05), outer ring temporal (t =－2.285, －2.610, －2.506; P＜0.05). ConclusionThe SE and AL of the occult myopia group and the control group increase with time, and the former increase more rapidly than the latter; the macular fovea, inferior and temporal side of the outer ring retinal become thinner, and the former become thinner than the latter.