Abstract
Purpose:
The meibomian gland is a known hormone target organ and has sex-associated differences in its anatomy and physiology. We previously reported that in females, meibomian gland physiology changes during the menstrual cycle (ARVO, 2007). The purpose of this present study was to assess the cyclic change of meibum fatty acid composition during the menstrual cycle in normal subjects.
Methods:
This study involved 6 healthy female subjects (age range: 29-36 years) with a regular 25- to 28-day menstrual cycle. The menstrual cycle was divided into 6 phases: 2 days prior to menstruation (phase VI), the first 2 days of menstruation (phase I), and the remaining time-period of the cycle (phases II-V). After a warm compress (40°C, 10 min) of both eyes using an electronic device (EH-SW50, Panasonic Corp., Osaka, Japan), meibum was obtained from the eyes by Daviel cataract spoon after gently squeezing the eyelid margin by use of a Yoshitomi meibomian gland compressor (T.M.I. Co. Ltd., Saitama, Japan). The spoon was washed with high-grade organic solvents and air-dried before each meibum sample collection to avoid lipid contamination. Meibum was transmethylated and analyzed using gas chromatography mass spectrometry. The concentrations of saliva hormones (i.e., estradiol, progesterone, free-testosterone, and dehydroepiandrosterone sulfate) were also evaluated.
Results:
The averaged fatty acid compositions were 41.5% saturated fatty acids (SFA) [5.2% straight-chain SFA (SSFA) and the other branched-chain SFA), and 58.5% unsaturated fatty acids (USFA) (51.1% mono-USFA (MUSFA), 3.4% poly-USFA (PUSFA), and 4.0% branched-USFA). In phase II, SSFA was significantly higher and MUSFA was significantly lower than in the other phases (p<0.05). The ratio of MUSFA was negatively correlated with the concentration of estradiol in the saliva during the menstrual cycle (p<0.05), but there was no correlation with the other hormones.
Conclusions:
Fatty acid composition showed cyclic change during the menstrual cycle. This may impact on tear film stability and relate to dry eye and/or contact lens intolerance in premenopausal women.
Keywords: 486 cornea: tears/tear film/dry eye •
583 lipids