Cohort study on the association between hyperopia reserve and myopia incidence in primary school students: the Anyang Childhood Eye Study

Abstract

Objective: To analyze the longitudinal association between hyperopia reserve and the cumulative incidence of myopia in grade 1 primary school students. Methods: Cohort study. This study included 2 628 grade 1 primary school students (2 628 eyes) who without myopic at baseline from the Anyang Childhood Eye Study. There were 1 515 male and 1 113 female, aged(7.16±0.40) years. Every year, cycloplegic autorefraction was performed with 1% cyclopentolate eye drops to obtain data of hyperopia reserve. Students with different ranges of hyperopia reserve at baseline were analyzed. Axial length, anterior chamber depth, corneal curvature, lens thickness, and other parameters were obtained by ocular biometrics and compared by the independent sample t test. Qualitative data were described by frequency and percentage, and comparison between groups was performed by the Chi-square test or exact probability method. Linear regression was used to analyze the association between baseline hyperopia reserve and spherical equivalent at 5 years. Results: The average hyperopia reserve was (+1.09±0.78) diopters (D) in grade 1 non-myopic children. Axial length, anterior chamber depth, corneal radius of curvature, and lens thickness were (22.66±0.72), (2.88±0.24), (7.80±0.25) and (3.62±0.19) mm, respectively. The cumulative incidence of myopia among non-myopic grade 1 primary school students was 8.5%, 21.5%, 35.6%, 47.6% and 64.1% at 1, 2, 3, 4 and 5 years, respectively. The incidence of myopia in girls was significantly higher than that in boys at 3, 4 and 5 years. The 5-year cumulative incidence of myopia was 4.6%, 26.3%, 52.3%, 78.6%, 92.6% and 94.3%, respectively, corresponding to students with baseline hyperopia reserve of >+2.00 D,+1.50 D to +2.00 D,+1.00 D to +1.50 D,+0.50 D to +1.00 D, 0.00 D to +0.50 D and -0.50 D to 0.00 D, and the difference was statistically significant (χ²=490.59, P<0.001). The regression equation between baseline hyperopia reserve and 5-year spherical equivalent was as follows: 5-year spherical equivalent=-3.135+1.692·baseline hyperopia reserve (R2=0.454, P<0.001). Conclusions: The lower the hyperopia reserve, the higher the incidence of myopia. Monitoring children's hyperopia reserve and early protection to reduce its consumption and timely detection of children at high risk of myopia are of great significance to prevent the occurrence and development of myopia.(This article was published ahead of print on the Online-First Publishing Platform for Excellent Scientific Researches of Chinese Medical Association Publishing House on March 15, 2022).