Effects of menstrual cycle on visual contrast sensitivity function of female fighter pilots

Objective To investigate the variations of visual contrast sensitivity (CS) function of female fighter pilots in different phases of menstrual cycle (menstrual phase, ovulation phase and luteal phase). Methods The contrast sensitivity of 10 male fighter pilots and 10 female fighter pilots in different menstrual cycle (menstrual phase, ovulation phase and luteal phase) under photopic, scotopic and scotopic+glare conditions at four different spatial frequencies (3, 6, 12 and 18 circle per degree) were measured with CSV-1000 and compared. Data of female were collected at three time points:the second day of the cycle (menstrual phase), the tenth day (vulation phase) and the twenty-second day (luteal phase). The differences between different cycles and gender were compared. Results No significant difference was found in CS between different phases of menstrual cycle in female pilots (P> 0.05). In menstrual phase:CS of female was better than that of male at 3 cpd (P=0.004) under photopic condition, 3 cpd (P=0.030) under scotopic condition and 18 cpd (P=0.001) under scotopic+glare condition. In ovulation phase:CS of female was better than that of male at 3 cpd (P=0.037) under photopic condition, 12 cpd (P=0.012) under scotopic condition and 6 cpd (P=0.015), 12 cpd (P=0.008), 18cpd (P=0.025) under scotopic+glare condition. In luteal phase:CS of female was better than that of male at 3 cpd (P=0.001) under photopic condition, 12 cpd (P=0.016) under scotopic condition and 18 cpd (P=0.033) under scotopic+glare condition. Conclusion Menstrual cycle has no effect on the CS of female pilots. Female fighter pilots are better than male fighter pilots in CS on certain frequencies in different menstrual cycle under the three environments mentioned above.