Validity of a computer-based risk assessment method for visual ergonomics

Abstract

ObjectiveTo describe the development of a computer-based risk assessment method for visual ergonomics, and assess its face validity, content validity, and internal consistency. MethodsThe risk assessment method contained a questionnaire for the worker, an evaluation form for the evaluator, a section of follow-up questions based on the worker's responses, and a section for recommended changes, including an overall risk assessment with respect to daylight, lighting, illuminance, glare, flicker, work space, work object and work postures, respectively. Forty-eight trained evaluators used the method to perform 224 workplace evaluations. Content validity of the method was assessed by the completeness and distribution of responses, and internal consistency was assessed by Cronbach's alpha, Spearman's rank correlation between items and indices, and exploratory factor analysis. ResultsThe proportion of missing values in items was generally low (questionnaire: 0–2.3%; evaluation form: 1.4–4.1%). In the questionnaire, items about double vision, migraine and corrective lenses had limited information content. Cronbach's alpha and item-index correlations for the indices frequency of eyestrain, intensity of eyestrain, visual symptoms, lighting conditions, frequency of musculoskeletal discomfort and intensity of musculoskeletal discomfort were satisfactory. Based on the factor analysis, suggestions for improving some of the indices were made. ConclusionOur findings suggest that this computer-based method is a valid instrument for assessing risks in the visual work environment. By incorporating subjective ratings by the worker as well as objective measurements of the work environment, it provides a good basis for recommendations with respect to daylight, lighting, work surfaces/material, and work object. Relevance to industryVisual environment factors, such as glare, can cause eyestrain, headache and musculoskeletal discomfort. This method satisfies the need of a valid tool for determining risks associated with the visual work environment. It contains both worker's ratings and objective measurements, and is designed to be used in different types of work.