Development and validation of the digital eye strain scale for children (DESS-C) aged 2–8 years: a Rasch Analysis

Digital eye strain is an increasing eye health concern among young children, yet validated caregiver-reported instruments for screening digital eye strain symptoms in children aged 2–8 years are lacking. This study aimed to develop and evaluate the reliability, validity, and screening utility of the caregiver-reported Digital Eye Strain Scale for Children (DESS-C). This instrument development and validation study included 533 caregiver–child dyads recruited from kindergartens and primary schools in Thailand. The DESS-C was developed through a literature review, semi-structured caregiver interviews, content validation, and face validation. Following classical item analysis of the 30-item field-test version, 27 retained items underwent Rasch modelling. Test–retest reliability and agreement were evaluated, while concurrent validity was assessed using the Digital Eye Strain Computer Adaptive Questionnaire (DESCAQ) and convergent and predictive validity using the Pediatric Quality of Life Inventory (PedsQL). Receiver operating characteristic (ROC) analysis assessed discriminative ability and identified a candidate screening threshold. The 27-item DESS-C demonstrated satisfactory Rasch model fit, with no substantial differential item functioning (DIF) by age or sex. Person reliability was 0.78 and person separation was 1.89. Test–retest reliability was good (intraclass correlation coefficient [ICC] = 0.90, 95% confidence interval [CI] 0.83–0.94), with high classification agreement (κ = 0.94, p < 0.001). Concurrent validity was supported by a strong correlation with the DESCAQ (ρ = 0.88, p < 0.001). Small negative correlations with PedsQL scores at baseline (ρ = −0.29) and 6-month follow-up (ρ = −0.25), both p < 0.05, supported convergent and predictive validity, respectively. ROC analysis yielded an area under the curve (AUC) of 0.91 (95% CI 0.88–0.95); a candidate screening threshold of ≥ 7 yielded 92.3% sensitivity and 79.0% specificity. The DESS-C demonstrated satisfactory psychometric properties and may be useful for screening digital eye strain symptoms in children aged 2–8 years. Further validation in diverse populations and against comprehensive ophthalmological assessments is warranted.