Astigmatism, a type of refractive error, creates two focal points in the eye, resulting in blurred retinal images and leading to blurred vision. This condition can cause amblyopia during the development of the visual system in children.1 Studies have even shown that simulated astigmatism can negatively impact children's academic performance.2 The main symptoms of astigmatism include reduced vision and visual fatigue, with some cases also presenting visual distortion, headaches, and other related issues. The prevalence of astigmatism varies in the literature depending on factors such as region, gender, race, and breastfeeding history.3 In recent years, the prevalence of astigmatism in children has been increasing, making it a significant clinical and public health concern.

Currently, most large-scale studies on the epidemiology of refractive errors in Chinese children focus on the prevalence of myopia, with less attention given to astigmatism. The literature has shown a significant correlation between astigmatism and the development of myopia.4–7 Therefore, it is essential to analyze the prevalence of astigmatism across different areas and educational stages in Xi'an, considering related influencing factors and the impact of astigmatism on myopia. This analysis will provide a basis for targeted management of astigmatism and myopia in different regions of Xi'an.

This study, conducted in collaboration with the Xi'an Education Bureau, aimed to assess the prevalence of astigmatism across different educational stages and regions. The prevalence of astigmatism in primary schools was 58.4% in urban areas and 51.8% in urban-rural fringes. In junior high schools, the prevalence was 71.0% in urban areas and 71.4% in urban-rural fringes. In senior high schools, the prevalence was 75.6% in urban areas and 67.4% in urban-rural fringes. Overall, the prevalence of astigmatism was 61.1% in urban areas, 58.3% in urban-rural fringes, and 59.321% across all areas.

In this study, the prevalence of astigmatism in Xi'an was higher than reported in similar studies from other regions in China and abroad, such as Guangzhou (33.6%),12 Xinjiang (36.1%),9 Hainan (31.9%),13 Iran (45.3%),14 China (16.5%).15 The high prevalence in Xi'an may be influenced by factors such as age, definition of astigmatism, regional differences,16 genetics,17 ethnicity,18 body weight,19 and other factors. Additionally, the prevalence of astigmatism was higher in urban areas than in urban-rural fringes, consistent with previous studies.15 This difference may be related to the duration of electronic screen use,20 eye habits,7 and exposure to sunlight. Urban children, who are exposed to screens earlier and for longer periods,21 experience prolonged eye strain,22 increased eye rubbing,23 and squinting, leading to a higher risk of myopia and astigmatism. In contrast, children in urban-rural fringes have more opportunities for outdoor activities, which helps prevent the development of astigmatism.21 Therefore, it is crucial to manage children's screen time, encourage outdoor and long-distance viewing, and reduce academic pressure, especially in urban educational settings.

Among different educational stages, the overall prevalence of astigmatism is highest among junior high school children, followed by senior high school children, while primary school children have the lowest prevalence. The most significant prevalence was observed in grade 9. This trend may be influenced by factors such as the large number of boarding students and left-behind children in the urban-rural fringe of Xi'an, where eye care habits are poorly regulated and medical resources are limited. A study24 indicated a bias in the accuracy of optometry in urban-rural fringe areas of western China, suggesting that inadequate medical care may lead to delayed correction of astigmatism. Uncorrected astigmatism significantly impairs visual function,25 adversely affects visual development, and can result in amblyopia.26 The highest prevalence of astigmatism was found in grade 9 students from urban-rural fringes and overall junior high schools in Xi'an. A study on risk factors for astigmatism in children and adolescents aged 7 to 19 years,9 found that 15-year-olds had a higher risk of developing astigmatism compared to 7-year-olds. Therefore, it is essential to focus on refractive errors in junior high school students, particularly those in urban-rural fringes. There is a need to actively promote the establishment of vision monitoring records for children and to strengthen astigmatism management. Early warning, detection, and diagnosis are crucial to prevent uncorrected astigmatism from leading to further vision loss.

The overall prevalence of astigmatism was higher in boys than in girls. This finding aligns with previous studies,9,27 although some research has reported a higher prevalence of astigmatism in girls or found no statistically significant difference between genders.1228 Meanwhile, the results of this study suggest that boys with high astigmatism are more likely to develop myopia than girls. This conclusion is similar to findings from a study conducted in China,29 which indicates a significant correlation between male gender and the incidence and severity of myopia or hyperopia with astigmatism. However, whether different genders with varying cylinder power contribute to a faster progression of myopia remains inconclusive, necessitating further research to clarify this relationship.

Additionally, this study observed that myopia worsened as astigmatism increased in children. This conclusion is consistent with relevant research findings. Increased astigmatism in children is associated with the onset and progression of myopia.30 Furthermore, myopic elongation is more significant when astigmatism > 1.0 D.7 This may be due to the regulation of ocular development during childhood by visual environmental stimuli and genetic factors,32 which tends towards emmetropia. The presence of astigmatism causes blurred signals and accommodative lag, leading to decreased accommodative function,31 potentially resulting in inaccurate axial elongation and the development of myopia.32 With-the-rule astigmatism is a common type of astigmatism, and the results of this study indicate that it is prevalent across different regions, ages, educational stages, and grades, consistent with earlier studies.71233 This type of astigmatism may be related to the tighter eyelid structure in Asian populations, which exerts pressure on the cornea.34 Early intervention for children with astigmatism that contributes to increased myopia is crucial,35 as managing astigmatism is one of the most important strategies for preventing and controlling myopia.

We analyzed the current prevalence of astigmatism across different regional schools in Xi'an, China. A key strength of this study is the large sample size, which allowed for a rapid collection of UCVA and non-cycloplegic SE data across various educational stages in both urban areas and urban-rural fringes. This provides a representative snapshot of the prevalence of astigmatism in the region and its relationship with factors such as location, gender, grade, educational stage, and degree of myopia. However, this study has some limitations. First, being cross-sectional, it only provides data from a single point in time, which does not allow for continuous dynamic observation, potentially introducing bias. Second, the use of non-cycloplegic screening may have led to an overestimation of myopia prevalence. Third, according to the national conditions of China, the Chinese government implemented nine years of compulsory education for primary and junior high school stages and required that school-aged children and adolescents enroll for free. As a result, the overall number of students in primary and junior high education stages was relatively large. This study focuses on Xi'an, one of China's key educational metropolises. In urban areas, educational resources are generally more abundant, and students face significant pressure to advance in their studies. Therefore, it is common to see a smaller sample size in urban areas while having a larger sample size in primary and junior high education stages. Therefore, although there are significant differences in the number of individuals across different educational levels, the included population and regions are representative. Additionally, the methodology adopted in this study allows for the rapid acquisition of large sample data, making it more suitable for school screening than cycloplegic optometry.

In conclusion, the overall prevalence of astigmatism was higher in urban areas compared to urban-rural fringes. In the same educational stage, the overall prevalence of astigmatism increases with the advancement of grades, while across different educational stages, the overall prevalence of astigmatism peaks in grade 9 of junior high school. At the same time, the prevalence of astigmatism among boys is consistently higher than that among girls at different educational stages. As astigmatism severity increased, the degree of myopia also worsened. With-the-rule astigmatism was predominantly conformal across axial types.

Astigmatism, one of the most common global vision problems,25 requires focused regional management36 across different educational stages in Xi'an. Attention should be given to gender differences in children with astigmatism. To control the occurrence and progression of astigmatism, healthcare providers39 must implement effective measures, including comprehensive systematic screening and referrals, educators37,38 advocating for increased outdoor activity time, reducing close-range learning, parents39 ensuring a healthy diet and sleep for children, and managing screen time to reducing its incidence and impact.

This research was funded by the Xi'an Municipal Bureau of Science and Technology (2024JH-YLYB-0305) and Xi 'an Health Commission(2022zp01).