2.8. Primary Outcome
The primary outcomes were visual functions (eye–hand coordination time and accuracy rate and visual motion reaction time through smooth-pursuit eye movement).Eye–hand coordination was measured using V-training 2G (Tokyo Optical Co., Ltd., Saitama, Japan). The V-training 2G was equipped with a monitor (inner dimensions: length 610 mm and width 1080 mm), which was adjusted to achieve the appropriate height and distance (30 cm) for each subject. At the start of the measurement, a target (a square of 22 mm in height and 22 mm in width) was displayed at random positions on the monitor, and the subjects quickly found the target with both eyes and accurately pointed to its center with their fingertips. After they had accurately pointed, the next target was randomly displayed on the monitor, and the subject again pointed to the target quickly. This task was repeated until 30 targets were identified. As an evaluation method, the time taken to finish pointing at the 30 targets was measured and designated as the eye–hand coordination time. The percentage of the 30 targets that were touched correctly was evaluated as the eye–hand coordination accuracy rate. The eye–hand coordination time and accuracy rate were evaluated three times, before and after the VDT operation, and the average value was calculated and used for evaluation.Smooth-pursuit eye movements were measured using V-training 2G. At the beginning of the measurement, a black circular target moved quickly (approximately 80 mm/s) and randomly on a V-training 2G monitor. The subject tracked the moving target with both eyes without moving their head while keeping their finger on the measurement button on the monitor. During this process, the color of the target changed from black to white at random times, and the subjects removed their fingers from the measurement button as soon as the color changed. The target color was changed three times during each set of evaluations. The time spent from the target color change to the release of the measurement button was evaluated as the visual motion reaction time for smooth-pursuit eye movements. This evaluation was conducted three times, before and after the VDT operation, and we calculated the average change in visual motion reaction time between the pre- and post-VDT operations.