Changes of luteinizing hormone (LH), estrogen and progesterone during the menstrual cycle influence the ocular physiology in both anterior and posterior segments. From the literature review, there were no significant differentiation in tear physiology, anterior chamber dept, lens thickness and refractive status. Some studies demonstrated then the central corneal thickness was thinner in the follicular phase, but this is non-conclusive. Advance in ophthalmic technologies provide few studies of posterior segment changes during the menstrual cycle, however, there were quite difference in methodology such as detection methods of ovulation.

There were 2 studies of posterior segment changes during the menstrual cycle. Akar et al showed significant decrease of neuroretinal rim area and increase of cupt area in late luteal phase. Ulas et al found that choroidal thickness was significant thicker in mid-luteal phase. However, the study of retinal vascular density by optical coherence tomography angiography (OCTA) during the menstrual cycle has never been published before.

Inclusion Criteria:

• Female with age 25-40 yr
• Normal body mass index (18.5-24.9)
• Regular menstrual cycle (28-32 days)
• Written informed consent

Exclusion Criteria:

• Pregnant women
• Lactating women
• Having childbirth or miscarriage within 6 months
• Systemic diseases which need taking the regular medication
• History of ocular disease such as glaucoma, retinal vascular diseases and macular disease
• History of hormonal taking such as oral contraceptive pills within 6 months
• History of intraocular laser and intraocular surgery
• Refractive error; spherical equivalent >4 diopters
• Can not taking the images by Optovue® such as spine diseases

Withdrawal criteria

• Pregnancy detection during the study period
• Receiving sex hormone during the study period such as emergency contraceptive pills