Radiology reading-caused fatigue and measurement of eye strain with critical flicker fusion frequency

Purpose. The aim of this study was to investigate eye fatigue that could impair diagnostic accuracy by measuring the critical flicker fusion frequency (CFFF) before and after reading. Materials and methods. CFFF was measured before and after about 4 h of health checkup reading in seven healthy volunteer radiologists. A questionnaire was also completed on duration of sleep the night before the experiment, average duration of sleep, and subjective fatigue using a visual analog scale (corrected to a 0-1 scale, 0 indicating the worst fatigue ever experienced). Results. After-reading subjective fatigue was significantly greater (before 0.52 +/- 0.15, after 0.42 +/- 0.15), and CFFF was significantly lower (before 40.9 +/- 2.4, after 39.9 +/- 2.0). There was no signifi cant correlation between subjective fatigue and CFFF, either before or after or between before-and after-reading differences in subjective fatigue and CFFF. Shorter duration of sleep the night before significantly correlated with lower CFFF (Pearson's correlation coefficient): before 0.42, P = 0.0047; after 0.52, P = 0.0003. Conclusion. CFFF declines after reading and can be considered useful as an indicator of fatigue induced by radiology reading. CFFF declines significantly when sleep is reduced the day before reading without correlation with subjective fatigue, meaning that sleep deprivation can cause an unaware decline in visual function.