Objective Assessment of Visual Workload in Video Display Terminal Workers Using a Non-Invasive Monitoring System

Background: The risk assessment for video display terminal (VDT) operators in occupational settings often relies on indirect estimates, such as self-reported screen time, which may not accurately reflect the true visual workload. The objective is to assess visual workload in VDT workers by measuring active screen fixation time with a non-invasive monitoring system and to explore its relationship with ocular surface alterations and fatigue-related indicators. Methods: An observational cross-sectional study was conducted on 38 administrative workers employed at a hospital booking center. Active VDT screen fixation, as well as shift duration and time spent in front of the VDT screen, were objectively measured using a patented video-based monitoring system. Ophthalmological evaluation included the Ocular Surface Disease Index (OSDI®), tear break-up time (BUT), and slit-lamp examination. Other investigated markers included blink rate, the Percentage of Eyelid Closure over the Pupil over Time (PERCLOS), and the Fatigue Assessment Scale (FAS). Results: Active screen fixation accounted for approximately 60% of the total recorded working time. Ophthalmological assessment identified alterations of the ocular surface in a substantial proportion of workers, with pathological BUT values observed in nearly half (47%) of the study population. No statistically significant associations were found between objectively measured fixation time and ocular or fatigue-related outcomes. PERCLOS80 and blink rate values remained within physiological ranges across the work shift. Conclusions: Objective measurement of screen fixation provides a more accurate characterization of visual workload among VDT workers than indirect exposure estimates and may support occupational health surveillance and risk assessment in VDT-exposed workers.