Tear volume and stability across the phases of the menstrual cycle among women in Benin City, Nigeria

Abstract

Background: The menstrual cycle has been reported to affect many physiological processes. While the effects of the menstrual cycle on ocular parameters have been studied extensively in Caucasian women, not much is known about its effect on tear volume and stability in Nigerian women. Objective: To investigate the changes in tear volume and stability during the different phases of the menstrual cycle in Nigerian women.Methods: A longitudinal study of one hundred healthy women with a regular cycle of 26 to 29 days was carried out. The women were between 20 to 35 years old with mean age of 30 ± 2.1 years. Tear volume was measured by the Schirmer's tear test, while tear stability was measured by the non invasive tear break up time (NITBUT). Results: The difference in mean tear volume across the phases of menstrual cycle was statistically significant (p = 0.001). Tear volume reduced during ovulation and rose again during the luteal phase. This difference was statistically significant (p=0.04). The difference in tear volume between the follicular phase and the luteal phase was not significant (p=0.3). Increase in mean tear stability between the follicular and ovulatory phases was marginally statistically significant (p=0.046). However, there was no statistically significant difference between the ovulatory and luteal phases (p=0.44). Conclusions: The findings of this study suggest that hormonal variation during the different phases of the menstrual cycle influence tear volume and tear stability in healthy young women of reproductive age. These changes may be clinically significant particularly in contact lens wearers where fluctuations in ocular parameter may alter the contact lens fit, leading to a possible change in comfort and reduced visual acuity.