Anisometropia in Children in Shandong, China: A Prospective Longitudinal Study

Abstract Purpose To determine the characteristics of anisometropia in children. Methods A total of 1474 children (4–15 years old) from 12 schools of Guanxian county (Shandong, China) were enrolled between December 2018 and June 2020 through cluster sampling. The changes of differences in spherical equivalent refraction (SER), axial length (AL) in different anisometropia, and the increases of SER, AL in new-onset anisometropia, non-anisometropia were evaluated over 18 months. Results Among 1474 children, 1347 (91.4%) children had a full set of data at the first visit. The prevalence of SER anisometropia was 8.5% at the first visit, and increased to 15.1% at the second visit (χ 2  = 27.077, P  < 0.001). Among children with SER anisometropia (n = 110), 25.45% (28/110) experienced an increase in anisometropia ≥ 0.5 D, whereas 20.91% (23/110) experienced a decrease in anisometropia ≥ 0.5 D, and 53.64% (59/110) with anisometropia were stable. For L eyes, the increase of SER was greater in the new-onset anisometropia than that in the non-anisometropia ( P  < 0.05); for H eyes, the increases of SER in the two groups were not significantly different ( P >  0.05). Conclusions The prevalence of anisometropia increased over time. Nearly half of children with anisometropia were unstable. The unilaterally greater rate of SER increase in children could be associated with the development of anisometropia.