Refraction and ocular biometric parameters of preschool children in the Beijing whole childhood eye study: the first-year report

Abstract

Background Prevention of myopia should begin before school age. However, few population-based cohort studies have investigated refractive status in preschool children with cycloplegia. This study aimed to investigate the post-COVID-19 refraction and ocular biometric parameters of preschool children in Beijing Tongzhou District. Methods A population-based cohort study of kindergarten children in Tongzhou District, Beijing, commenced in November 2021. The present study reports data from the first year of the aforementioned population-based study. We selected children aged 3–6 years from nine kindergartens. Biometric parameters, including axial length (AL), anterior chamber depth (ACD), and corneal radius of curvature (CR), were collected before cycloplegia. Cycloplegic refraction was also measured. The spherical equivalent (SE), lens power (LP), and AL-to-CR ratio were calculated. Multiple linear regression analysis was used to analyse the correlation between refraction and ocular biometric parameters. Results A total of 1,505 children completed the examination, and a mean SE of 1.24 ± 0.91 D was found. The overall prevalence of myopia was 1.93%. The mean AL, ACD, CR, LP, and AL-to-CR ratio were 22.24 ± 0.70 mm, 3.28 ± 0.26 mm, 7.77 ± 0.26 mm, 26.01 ± 1.56 D, and 2.86 ± 0.07, respectively. Longer AL, deeper ACD, larger AL-to-CR ratio, and lower LP were associated with older age; the CR was not significantly different among different ages. In the multiple linear regression analysis, after adjusting for sex and age, the model that included AL, CR, and LP explained 87% of the SE variation. No differences were observed in the prevalence of myopia or the SE in this particular age range. Conclusion The findings of this study suggest that a large proportion of preschool children in Beijing are mildly hyperopic, with a considerably low prevalence of myopia. In preschool children, refractive development was found to present mild hyperopia rather than emmetropia or myopia, a phenomenon that is characteristic of this age range.

Refraction and ocular biometric parameters in 3-to 6-year-old preschool children : a large-scale population-based study in Chengdu, China

“…This study indicated that in preschool children aged 3–6, older children tend to have longer AL, generally longer CR, deeper ACD, thicker CCT, thinner LT, and VCD. The growth and development patterns of these ocular biometric parameters were consistent with previous literature [ 19 , 20 ]. The results aligned with the characteristic of a relatively rapid increase in AL during the preschool period of 3–6 years, similar to findings in other studies [ 17 ].…”

“…This study indicated that in preschool children aged 3–6 years, the AL/CR ratio increased with age, rising from 2.83 ± 0.08 to 2.90 ± 0.08. These values closely resembled the results obtained in studies of preschool children aged 3–6 years in Beijing and Shenzhen [ 19 , 20 ]. Some scholars have noted that using AL/CR ratio alone for predicting myopia in the 3–5 age group may be relatively inaccurate.…”

“…In this study, the prevalence of myopia among preschool children aged 3–6 in Chengdu was 6.1% (non-cycloplegia), similar to the myopia prevalence among children aged 4–6 in Shanghai, China, which was 5.9% (non-cycloplegia) [ 18 ]. However, the prevalence of myopia among children aged 3–6 in Beijing was 1.93% (post-cycloplegia) [ 19 ], it was 1.3% in Shenzhen(post-cycloplegia) [ 20 ], and it was 3.7% in Shanghai(post-cycloplegia) [ 21 ]. Additionally, the myopia prevalence among non-Hispanic White and Asian children aged 0.5-6 years was 1.20% and 3.98% (post-cycloplegia) [ 22 ], which were significantly lower than the findings of our study.…”

“…However, some studies have shown a contrary trend, with two cycloplegic refraction studies in Shanghai showing that the prevalence of myopia increases with age in preschool children aged 3 to 6 years [ 21 , 25 ]. Additionally, a cycloplegic refraction study in Beijing revealed an increase in myopia prevalence among children aged 4 to 6 with increasing age [ 19 ]. Overall, while the prevalence of myopia among preschool children aged 3 to 6 is generally low and relatively stable, differences in study outcomes across different locations may be influenced by sample size and study methodological factors such as cycloplegia.…”

“…The results of this study indicated that the prevalence of hyperopia among children aged 3–6 in Chengdu was 35.8% (non-cycloplegic), which was significantly lower compared to the hyperopia prevalence in Beijing and Shenzhen (cycloplegic, 85.1%, 93.4%) [ 19 ]. The substantial difference in hyperopia prevalence between this study and others may be related to the non-cycloplegic refraction.…”