Changes in pattern reversal evoked potentials during menstrual cycle.

Hormonal changes that occur during the menstrual cycle of women influence the visual function of females. Estrogen is reported to cause a decrease in the visual transmission time by increasing the sensitivity of receptors in the optic pathways to dopamine. The aim of this study was to search if pattern reversal evoked potentials (PRVEPs) changed during the different phases of the menstrual cycle. PRVEPs of both eyes of 30 healthy women were recorded in 4 different phases of the menstrual cycle, namely, menstrual, follicular, ovulatory and luteal. The highest mean PRVEP latency and the lowest mean P100 amplitude were recorded during the menstrual phase. The mean PRVEP latency recorded during the ovulatory phase (when estrogen level rises to 3-5 times that of other phases' without an increase in progesterone levels) was statistically significantly shorter than that of other phases' (p<0.05). Although not statistically significant, the mean P100 amplitude recorded during the ovulatory phase was higher than the other phases. Looking at these results, sex steroids seemed to affect the generation of PRVEPs. The significant decrease in PRVEP latencies when estrogen levels peaked was thought to be due to facilitating effect of estrogen on the neural transmission of the visual pathways.