Variations in corneal biomechanical parameters and central corneal thickness during the menstrual cycle

PURPOSE: To assess variations in the biomechanical properties and central corneal thickness (CCT) throughout the female menstrual cycle. SETTING: Department of Ophthalmology, Assaf Harofeh Medical Center, Zerifin Israel. DESIGN: Case series. METHODS: Young healthy women were prospectively recruited. Every participant was assessed at the beginning of the menstrual cycle, at ovulation, and at the end of the cycle. At every time point, corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured with the Ocular Response Analyzer and the CCT was measured with an ultrasonic pachymeter. RESULTS: Twenty-two eyes of 22 women (mean age 19.5 years +/- 1.5 [SD]) were included. The CH was statistically significantly decreased at ovulation (10.1 mm Hg) compared with the beginning (11.1 mm Hg, P<.001) and the end (11.4 mm Hg, P<.001) of the cycle. The CRF was also significantly decreased at ovulation (9.8 mm Hg) compared with the beginning (10.6 mm Hg, P<.001) and the end (10.5 mm Hg, P<.001) of the cycle. The central cornea was thinnest at the beginning (535 pm) and statistically significantly thicker at ovulation (542 mu m, P<.001) and at the end of the menstrual cycle (543 mu m, P<.001). CONCLUSIONS: The CCT and biomechanical parameters significantly varied during the menstrual cycle. The CH and CRF were temporarily decreased at ovulation. The cornea was thinnest at the beginning and thicker at ovulation and at the end of the cycle. Such corneal changes may be important to consider during screening of candidates for laser refractive surgery.