Changes in corneal thickness, curvature, and anterior chamber depth during the menstrual cycle

Objective: To determine the variations in corneal thickness values, keratometry readings, and anterior chamber depths (ACD) during the menstrual cycle of young women using the noncontact Scheimpflug imaging technique. Design: Prospective cohort study. Participants: Fourteen women with regular menstrual cycles who were not taking contraceptive pills were enrolled and had measurements taken every other day during a full menstrual cycle, starting from the first day. None used contact lenses or regular medication, and none had systemic disease or history of eye surgery. Methods: The thickness at the centre, superior, inferior, temporal, nasal, and thinnest point of the cornea, the keratometry readings, and the ACD values measured with the Pentacam were recorded. We used data on days 1, 3, and 5 of the studied cycle, and counting backwards, 2, 4, 6, 12, 14, and 16 days before the first day of the next cycle. Results: The mean differences between 2 points of time were not statistically significant (p > 0.05) for any variable. The mean difference between any 2 paired thickness measurements was less than 5.0 mu m. Conclusions: Contrary to our expectations and previous findings using ultrasound pachymetry, we found no clinically or statistically significant differences between the repeated measurements with the Pentacam. This could indicate that the Pentacam is a clinical tool with less variability when performing serial measurements and follow-up examinations.