The effect of VDT work on the fluctuations of accommodation.

Fluctuations in accommodation, accommodative function, visual acuity and subjective symptom were investigated on the basis of two hours of character search work by VDT operators. As a means to determine the visual load encountered in VDT work, the fluctuations in accommodation were analyzed using the computer method developed by the authors in eight young women. Visual acuity and amplitude of accommodation in the dominant eye diminished with VDT work time. In terms of the fluctuations in accommodation, it was found that, as VDT work time progressed, the frequency of the peak frequency band range lowered and the low-frequency ratio increased. Compared to the pre-test level, there was a significant increase in the low-frequency ratio after 2 hours of VDT work. With time, the mean number of complaints of eye strain and fatigue increased significantly in VDT work. The low-frequency ratio of fluctuation in accommodation was showed to increase before the number of complaints were found to increase. Results suggested that computer analysis using the scale method offers a faster, more objective approach to measure visual load from VDT work.