Reliability of a new risk assessment method for visual ergonomics

Introduction: The Visual Ergonomics Risk Assessment Method (VERAM) is a newly developed and validated method to assess visual ergonomics at workplaces. VERAM consists of a questionnaire and an objective evaluation. Objective: To evaluate reliability of VERAM by assessing test-retest reliability of the questionnaire, and intra- and inter-rater reliability of the objective evaluation. Methods: Forty-eight trained evaluators used VERAM to evaluate visual ergonomics at 174 workstations. The time interval for test-retest and intra-rater evaluations was 2–3 weeks, and the time interval for inter-rater evaluations was 0–2 days. Test-retest reliability was assessed by intraclass correlation (ICC), the standard error of measurement (SEM) and the smallest detectable change (SDC). Intra- and inter-rater reliability were assessed with weighted kappa coefficients and absolute agreement. Systematic changes were analysed with repeated measures analyses of variance and Wilcoxon sign rank test. Results: The ICC of the questionnaire indices ranged from 0.69 to 0.87, while SEM ranged from 7.21 to 10.19 on a scale from 1 to 100, and SDC from 14.42 to 20.37. Intra-rater reliability of objective evaluations ranged from 0.57 to 0.85 (kappa coefficients) and the agreement from 69 to 91%. Inter-rater reliability of objective evaluations ranged from 0.37 to 0.72 (kappa coefficients) and the agreement from 52 to 87%. Conclusion: VERAM is a reliable instrument for assessing risks in visual work environments. However, the reliability might increase further by improving the quality of training for evaluators. Complementary evaluations of VERAM's sensitivity to changes in the visual environment are needed. Relevance to industry: It is advantageous to set up a work environment for maximal visual comfort to avoid negative effects on work postures and movements and thus prevent visual- and musculoskeletal symptoms. This method, VERAM, satisfies the need of a valid and reliable tool for determining risks associated with the visual work environment.