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

Abstract To determine the prevalence, demographic distribution, and predictors of refractive error among school-aged children in Bhutan using secondary data from the Bhutan School Sight Survey (BSSS), and to compare these population-level findings with standardised estimates from the Refractive Error Study in Children (RESC). Secondary data from 586 schools, comprising 166,357 school-aged children (5-18 years), 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. Data on demographic characteristics (age, gender), school type, school level, and geographic location were analysed using descriptive statistics. Logistic regression was used 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%). Refractive error (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 female sex, private school attendance, and urban schooling (Thromdes) as significant RE predictors (p < 0.01). Of 19,234 children diagnosed with RE, 96.2% received spectacles within four months; 3.8% were lost to follow-up. Effective spectacle coverage was 11.5%.In Bhutan, refractive error affects over 10% of school-aged children, with higher prevalence among females, urban students, and those in private schools highlighting equity gaps in eye health. These findings are consistent with prior estimates derived from the Refractive Error Study in Children (RESC) protocol and underscores the need for sustained, targeted school-based eye care. The BSSS also shows that comprehensive screening is feasible and scalable in resource-limited settings.