Influence of VDT (visual display terminals) work on eye accommodation

Visual display terminals (VDT) are popular in offices. Many VDT operators have complained about eye-function impairment. Experiments using an accommodo polyrecorder and an infrared optometer showed that visual tasks in VDT work might induce temporary effects in the visual accommodation system; prolonged the near point distance and the contraction time of accommodation and increased the low frequency component of the small fluctuation of accommodation after VDT work. The inhibition of accommodation caused by VDT work was more severe than that caused by the conventional hard-copy work, and changes in the accommodative function were found with statistical significance in the smaller-size character group but tended to deteriorate in the larger-size character group. The inhibition was more evident in the elderly and middle age groups than in the young age group. The inhibition of accommodation by VDT work might be inhibited by administration of methylcobalamin.