Prevalence and determinants of refractive error among school children in two Southern districts of Karnataka

Background: Refractive error (RE) is a major cause of visual impairment in schoolchildren, affecting learning and long-term eye health. Its prevalence varies across India, with limited data from southern Karnataka. This study assessed RE prevalence and determinants among children aged 6-16 years. Methods: A school-based cross-sectional study was conducted from July to October 2025 among 1,070 students selected through cluster sampling using probability proportionate to size (PPS). Within each school, participants were chosen by simple random sampling. Data were collected using a structured proforma capturing sociodemographic, familial, clinical, and behavioural factors. Visual acuity was assessed using a standardized Snellen chart protocol. Statistical analysis included descriptive measures and Chi-square tests to determine associations between RE and selected variables. Results: The prevalence of RE was 8.2%. Age and educational grade showed significant associations (p=0.005), with older children presenting higher impairment. Significant determinants included history of eye infection (p=0.027), family history of glasses (p=0.024), and screen exposure (p=0.014), with RE rising from 6.2% in low screen-time groups to 16.7% in high-exposure groups. Gender, parental education, family type, and history of eye injury were not significantly associated. Conclusions: RE remains a notable concern among schoolchildren in southern Karnataka. Findings highlight the role of biological and behavioural determinants, underscoring the importance of strengthened school-based screening and early preventive interventions.