Refractive error among school-aged children in Bhutan: A secondary analysis of data from nationwide Bhutan School Sight Survey

Abstract

This study aimed to determine the prevalence, demographic distribution, and predictors of refractive error (RE) among school children in Bhutan using secondary data from the 2019 Bhutan School Sight Survey (BSSS). It also sought to compare these population-level findings with standardized estimates from the Refractive Error Study in Children (RESC). Secondary data from 586 schools, comprising 164,365 school-enrolled children aged 5-18 years (94.3% of the national school-age population), were analyzed. As part of the BSSS, vision screening and cycloplegic refraction were conducted following the RESC protocol. Spectacles were provided at no cost to children requiring correction. Descriptive statistics were used to analyse data on demographic and school-related variables, and logistic regression to identify associated predictors. Findings were compared with previously published RESC data to contextualise observed trends. Visual impairment (VI) affected 12.14% (95% CI: 11.98-12.30) of school-aged children in Bhutan, with higher rates in females (13.16%) than males (11.07%) (p < 0.01). RE was the leading cause, accounting for 11.71% of all cases and 96.1% of VI. Myopia was most common (5.78%), followed by astigmatism (5.26%) and hypermetropia (0.67%). Multivariate analysis showed that female students (AOR = 1.18), those in private schools (AOR = 1.41), and urban schooling (AOR = 1.68) were significant RE predictors (p < 0.01). Of 19,243 students diagnosed with RE, only 11.5% had appropriate spectacles. Among those needing new spectacles (n = 17,021), 96.2% eventually received them within four months, while 3.8% were lost to follow-up. In Bhutan, RE affects over 10% of school children, primarily due to myopia and astigmatism. The higher burden among females, urban students, and private schools highlights persistent inequities. These results are consistent with prior RESC findings and demonstrate that large-scale school screening is both feasible and scalable. Strengthening school-based vision services, timely spectacle delivery, and cross-sectoral coordination are essential to close the gap and address uncorrected RE.