High Building Density May Accelerate Myopia Progression

This study, conducted in Shanghai—one of the most densely populated cities in the world—underscores the importance of incorporating public health considerations into urban planning, such as vision and eye health, with regulations on building density near schools to reduce myopia risk. Photo: Road Trip with Raj on Unsplash. Click image to enlarge. While myopia is widely known as a significant concern rising in prevalence among children and adolescents worldwide, the relationship between the refractive error and a possible factor of the condition—building density—is unknown. In a recent study, Chinese researchers explored the relationship between school-level built environment factors (building density and height) and myopia prevalence and found that building density, not height, may accelerate myopia progression, particularly among boys ages 12 years and older. The findings were reported in British Journal of Ophthalmology.Students from public schools and kindergartens in all 16 districts of Shanghai underwent visual acuity testing and noncycloplegic refraction between 2019 and 2023. Data from just over 8.6 million participants were analyzed, with 1.1 million followed consistently. Building density and height within 500m and 1,000m buffers around the schools were obtained, and age, gender, outdoor activity time and near-work time were collected through questionnaires. Logistic mixed-effect models were used to analyze the association between the building environment and myopia, adjusting for relevant demographic and behavioral factors.This study found a significant association between higher building density around schools and increased myopia prevalence among students. In contrast, average building height within the same buffer zones was not significantly associated with myopia risk. The authors pointed out several potential mechanisms to explain this. While high-density areas often reduce green spaces and outdoor activity opportunities—which protect against myopia— these findings showed that outdoor time had a limited mediating effect between building density and myopia.“Second, high building density often obstructs natural light exposure, limiting the amount of outdoor light children in these areas receive, thereby reducing the protective effect of light on eye growth,” the authors wrote. “Additionally, areas with higher building density typically have increased levels of air pollution, which may contribute to myopia development by inducing ocular inflammation or directly irritating eye tissues.”Lastly, the researchers explained that high building density often obstructs long-distance views, which can discourage children from engaging in activities that promote distance vision, further exacerbating the risk of myopia. Children living in densely built areas may be more prone to prolonged screen time and near-work.“Thus, our findings support the hypothesis that building density negatively impacts myopia development through environmental and behavioral mechanisms,” the team wrote. They go on to suggest that “effective interventions may need to address factors beyond merely increasing outdoor activity.”The increased effects of building density in students aged seven to 12 might be associated with rapid refractive development and hormonal changes characteristic of this age group, the authors pointed out. This study showed that boys, particularly those over 12 years old, were more sensitive to the impact of building density on myopia risk; however, previous studies suggested that girls were more affected by high building density.“This discrepancy might have been due to differences in behavior, as girls typically engage in more indoor activities during and after adolescence, while boys are more likely to participate in outdoor activities, potentially leading to differing sensitivities to environmental factors,” the researchers wrote in their paper. “Therefore, further research is needed to better understand the influence of building density on myopia across different age groups and genders.”With no significant association found between building height and myopia, this suggests that horizontal building density has a more substantial impact on myopia development than vertical height. In addition, the influence of building environments on myopia risk varied across different regions.“Within both the 1km and 0.5km radius, higher building density in inner suburban areas significantly increased the risk of myopia in children and adolescents,” the authors noted. “The mixed nature of inner suburban areas, which lack both the extensive outdoor activity spaces of outer suburbs and the abundant recreational facilities of central urban areas, may explain the more pronounced effect of building density on myopia in these regions.”To reduce the myopia risk, the authors suggest that urban planning should consider vision health, with regulations on building density near schools.“Future research should further explore these findings, focusing on controlling additional potential confounders to better understand the long-term impact of the built environment on myopia and to inform effective prevention strategies,” the authors concluded.Click here for the journal source. Wang J, Chen J, Gong W, et al. Association between building density and screening myopia in children and adolescents: a five-year longitudinal study from China. Brit J Ophthalmol. August 25, 2025. [Epub ahead of print.] This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.