Gur S, Ron S
Physiology Unit, Occupational Health and Rehabilitation Institute, Loewenstein Hospital, Raanana, Israel.
Isr J Med Sci. 1992 Aug-Sep;28(8-9):618-21.
After several hours of work with a visual display unit (VDU), operators become myopic for a short time. Such transient myopia may be evaluated by measuring contrast sensitivity to a modulated grating pattern. The aim of the present study was to determine whether there are any accumulative myopic effects after 1 day of VDU work. We examined grating contrast sensitivity in a group of 13 full-time workers and in 13 office employees who used VDUs only sporadically. The results, which were compared with the near point of accommodation, clearly illustrated that there is no decrease in contrast sensitivity. In the VDU group the decrease in the near point of accommodation was uniformly distributed between zero and 1.0 diopter, whereas among the non-VDU workers 77% of the decrease was between zero and 0.25 diopter. We conclude that the myopic changes in the refractive status of operators after VDU work are not evident in a decrease in contrast sensitivity. However, in VDU workers the dynamic range of accommodation was smaller, suggesting that the visual fatigue and visual stress that developed at work hindered visual activities after work.
在使用视觉显示单元（VDU）工作数小时后，操作人员会出现短时间近视。这种短暂性近视可通过测量对调制光栅图案的对比敏感度来评估。本研究的目的是确定VDU工作1天后是否存在任何累积性近视效应。我们检查了一组13名全职工作人员以及13名仅偶尔使用VDU的办公室职员的光栅对比敏感度。将结果与调节近点进行比较，结果清楚地表明对比敏感度没有下降。在VDU组中，调节近点的下降均匀分布在0至1.0屈光度之间，而非VDU工作人员中77%的下降在0至0.25屈光度之间。我们得出结论，VDU工作后操作人员屈光状态的近视变化在对比敏感度下降方面并不明显。然而，在VDU工作人员中，调节的动态范围较小，这表明工作时产生的视觉疲劳和视觉压力妨碍了工作后的视觉活动。
