Variations in central corneal thickness during the menstrual cycle in women

We report changes in the central corneal thickness during various phases of the menstrual cycle.

We recruited 16 healthy women of reproductive age and measured the central corneal thickness at 3 points in their menstrual cycle, beginning on days 1 to 3 and again at ovulation and at the end of the cycle (days 27-32). Ovulation was determined with a test that determines the peak of luteinizing hormone in the urine.

We found that the central cornea was thinnest at the beginning of the cycle (mean = 536 microm). Corneal thickness increased at ovulation (mean = 549 microm) and at the end of the cycle (mean = 559 microm). The difference in corneal thickness was statistically significant at ovulation (P = 0.003) and the end of cycle (P = 0.001) compared with values at the beginning of the cycle.

The central corneal thickness changes during the menstrual cycle; the cornea is thinnest at the beginning of the cycle and thickest at the end. These changes could be secondary to hormonal influences; estrogen receptors can be found in human corneas, suggesting that estrogen may have a role in corneal physiology.