Students in Urban Areas More Likely to Have Myopia, Anisometropia

School children who live in urban areas in China were more likely to have myopia and anisometropia compared with children who live in rural areas. They were also less likely to have hyperopia than children who live in rural areas.

These study findings were recently published in Frontiers in Public Health.

Myopia has seen an increase in global prevalence in the past 50 years, especially in East Asian countries like China. Refractive errors like myopia are the primary cause of preventable blindness in children.

This study was done in December 2018. A district from the Wafandian County and Xigang District regions of Dalian was selected for the rural and urban sample size, respectively, of school children aged 6 to 18 years. A primary school, junior high school, and senior high school were selected from each of the districts and 2 classes of each grade were selected from each of the schools. Patients were excluded if they had eye conditions in the last month or did not have parental consent.

All students and parents filled out a questionnaire at home that included sociodemographic data like age, gender, ethnic origin, habitation in urban or rural areas, and medical history. Questions on how long each participant studied, watched television, used their mobile phone, or were on their computer were also asked. Ophthalmological exams were also conducted at the school, and parental history of vision problems was recorded.

There were 4583 participants included in the study, 2336 of which were boys. There were more children aged 6 to 15 years in the rural group and more aged 16 to 18 in the urban group. Urban students also were more likely to have parents with refractive errors, higher parental education level, and daily hours of outdoor activities.

The prevalences of overall, low, moderate, and high myopia were 82.71%, 70.52%, 50.88%, and 38.68%, respectively, in urban students, which was higher than in rural students (71.76%, 58.54%, 32.16%, and 21.55%). The prevalence of anisometropia was also higher in urban students than in rural (7.27% vs 5.41%), but the prevalence of hyperopia was higher in rural than in urban students (10.21% vs 5.63%). No difference was found in astigmatism between the students in different regions.

Students’ age, region of habitation, average parental refractive error, parental education level, annual household income, and daily hours of near work were all associated with myopia, hyperopia, and astigmatism.

A multiple logistic model found that the risks of students developing myopia, hyperopia, and anisometropia were 1.88 (95% CI, 1.62-2.18), 0.53 (95% CI, 0.43-0.65), 1.07 (95% CI, 0.94-1.21), and 1.37 (95% CI, 1.07-1.76), respectively, in urban students. There was no difference in presence of astigmatism between rural and urban students (odds ratio, 1.07; 95% CI, 0.94-1.21).

A bivariate analysis found that students in urban areas were 1.80 (95% CI, 1.53-2.11) times more likely to be myopic, 1.29 (95% CI, 1.00-1.67) times more likely to be anisometropia, and 0.54 (95% CI, 0.43-0.67) times less likely to be hyperopia.

There were 2 limitations to this study. There was an inability to validate the causal relationship between the risk factors and the presence of refractive errors. The prevalence of myopia may also have been lower due to the exclusion of participants with optical correction.

The researchers concluded that students aged 6 to 18 years in urban habitation had a higher prevalence of myopia and anisometropia than those in rural areas. However, those in urban areas had a lower risk of hyperopia compared with those in rural areas.

Reference

Wang Y, Liu L, Lu Z, et al. Rural-urban differences in prevalence of and risk factors for refractive errors among school children and adolescents aged 6–18 years in Dalian, China. Front Public Health. 2022;10:917781. doi:10.3389/fpubh.2022.917781