[Changes in visual function caused by work at a data display terminal].
Working at video display terminals (VDTs) is particularly demanding in terms of orthopaedic and visual functions. This study was initiated to examine whether, and if so how, VDT work can influence the visual system. It was designed as a 5-year-prospective study based on the matched-pairs technique. The subjects were examined at the beginning and after 5 years of VDT work. The study group consisted of 102 people working at VDTs, and these were paired with 102 other office workers who did not use VDTs. The legally prescribed screening examinations of visual acuity (distance and near vision, phorias, stereopsis, and colour vision) were carried out. We also checked the anterior segments by examination with the slit-lamp and the fundus by ophthalmoscopy. Break-up time, Schirmer-I test, perimetry and tonometry were included in our range of examinations. We found a significant difference in asthenopia and daily hours of VDT work between VDT workers working less than 6 h daily and those working more than 6 h daily. In the study group pre-existing exophoria seemed to increase, but no statistical significance was found on testing. Nor was there any significant difference between the study group and the control group in the parameters examined in the course of the screening examination. In our investigation of monocular VDT workers (n = 3) we could not find any visual problems.