PurposeTo evaluate the occurrence and influencing factors of myopia occurrence in pre-myopia children aged 3–6 years. MethodsThis study included 204 pre-myopia (-0.50D<Spherical equivalent (SE) ≤+0.75D) children with three years follow-up in Beijing Hyperopia Reserve Research. All participants underwent a comprehensive eye examination. The length of macular Bruch's membrane (BM) and the temporal vascular arcade angles were measured upon fundus photographs. ResultsMean age at initial visit was 4.28±0.98 years and mean SE was 0.45±0.29D. Both at baseline and after 3 years of follow-up, axial length was longer in boys than in girls. (all P<0.001) Children were divided into two groups according to the refractive status of children at the final follow up: Myopia group (SE≤-0.50D) and Non-myopia group (SE>-0.50D). The length of macular BM was shorter in Myopia group than that in Non-myopia group (P<0.001). Baseline SE and the length of macular BM were independent influencing factors which associated with myopia occurrence (OR, 0.031; 95% CI, 0.008–0.117, P<0.001 and OR, 0.204; 95% CI, 0.055–0.763, P=0.018, respectively) by multivariate binary logistic regression analysis. SE changes process represents the changes of SE, Myopia group had the bigger SE changes (P<0.001). And in the multivariate liner regression analysis, age was the common influencing factor of SE changes process in total participants, Non-myopia group and Myopia group (B=0.244, P<0.001; B=0.078, P=0.010; B=0.161, P=0.046, respectively) ConclusionsInitial SE and the length of macular BM in pre-myopia children aged 3–6 years were the independent factors of the occurrence of myopia. And initial age was the common factor that associated with SE changes process.