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

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.

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).

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.

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.