VDT（visual display terminals）と眼精疲労

A phenomenon of reduced efficiency of visual work after performing some extent of that work is referred to as fatigue phenomenon. Eye strain is defined as a physiological condition where fatigue level is proportionate to the work load, while asthenopia is defined as a pathological condition where fatigue level is not proportinate to the work load. A terminal device of computer that is used for visual confirmation of input and output of data entry is called a visual display terminals (VDT), and such a work is called VDT works. Asthenopia is the main health hazard caused by such VDT works. Three factors are involved in development of asthenopia : visual oragan, psychological and environment factors. Asthenopia due to VDT works is primarily characterized by reduced range of accommodation, and is accompanied with longterm complications of development of myopia and glaucoma. The effective treatment measures include improvement of working environment and VDT health examination.