Effects of VDT task duration, display curvature, and aged eye on visual fatigue

Abstract

Previous studies reported that visual display terminal (VDT) tasks are associated with diverse visual fatigue symptoms that can reduce work efficiency and task performance. Such results can be more severe for older individuals as visual abilities diminish with age. Curved display provides relatively similar visual distances across display surface for the center viewer than flat display, which could benefit viewing experience while inducing less visual fatigue. Indeed, some studies on display curvature demonstrated that curved display is more effective than flat display in terms of task performance and preference. The aim of this study was to examine agerelated differences in visual fatigue and satisfaction due to VDT task duration and display curvature. Each of 64 participants (32 per age group) in the present study performed a proofreading VDT task for one hour. Task duration (0, 15, 30, 45, 60 min), display curvature (600mm, 1140mm, 4000mm, flat) and age group (younger, older) were independent variables. Pupil diameter, bulbar conjunctival redness, subjective visual fatigue by ECQ (Eye Complaint Questionnaire), and satisfaction level were measured every 15min, while CFF (Critical Fusion Frequency) was measured before and after the 1-hour proofreading task. Over the 1-hour task, pupil diameter decreased, bulbar conjunctival redness increased, CFF decreased, and ECQ increased, all indicating an increase in visual fatigue. Pupil diameters changed least at the 1140mm curvature, at which, though not significant, the satisfaction level of the older group also gradually increased over the 1-hour task, indicating a less increase in visual fatigue. These findings can be utilized when determining work-rest schedule and display curvature for VDT tasks.