VDT作業と紙面作業でのフリッカー値の比較

Critical flicker frequency following work with visual display terminal and paperwork

　今回筆者らは，VDT （Visual display terminal）作業と紙面作業での視機能への影響を調べるために，60分のアルファベット修正作業と，その後に90分の休憩を設け，その経時的変化を赤色・緑色・黄色のフリッカーのチラツキ閾値と融合閾値を測定し比較検討した。その結果，VDT作業と紙面作業では低下傾向に差が認められたが，回復傾向では認められなかった。赤色は緑色・黄色より大きな変動を示し，融合閾とチラツキ閾では，チラツキ閾の低下が大きく，VDT作業では90分休憩後でも完全には回復しなかった。フリッカー値によるVDT作業の疲労現象は長期に存続し，特に赤色でのチラツキ閾測定が，作業形態による疲労度を反映し易く有益であると思われた。

Eleven healthy young volunteers of both sexes were asked to work on spelling conversion of alphabets for 60 minutes using visual display terminal (VDT) and as paperwork on two different sessions. They were tested for critical flicker fusion frequency (CFF) with red, green and yellow lights and for flicker threshold (FT) before, during and after the works. During loading, both CFF and FT for the three colors showed greater decrease while working on VDT than on paper. CFF and FT for red showed greater decrease during loading and for 90 minutes after the end of VDT work. In all situations, deterioration of FT was more pronounced than CFF. The findings show that visual fatigue due to VDT work persist for 90 minutes or more and that FT for red is more sensitive in the detection of visual fatigue.