title: Menstrual phase-related differences in the pulsatility index on the central retinal artery suggest an oestrogen vasodilatation effect that antagonizes with progesterone.
abstract: OBJECTIVE
  The actual effect of steroid hormones on cerebral microcirculation is still controversial. Therefore, the aim of our study was to investigate vascular flow variations in the central retinal artery that may exist during the ovulatory menstrual cycle.
  
  
  METHODS
  A total of 34 healthy women were included in this observational, longitudinal, and prospective study. All participants were submitted to dopplerfluxometric evaluation of the eyes in order to study the pulsatility index (PI) of the central retinal arteries, during four phases of the menstrual cycle: early follicular, mid follicular, periovulatory, and mid luteal phases.
  
  
  RESULTS
  Subjects' ages ranged from 14 to 47 years old (mean: 29.7 ± 10.1) and PI did not differ among age groups. The PI of the central retinal artery was different among the four phases of the menstrual cycle. PI showed a significant decrease from early follicular phase (1.72) to mid follicular phase (1.57) (p = 0.037), and was similar during periovulatory phase (1.56) and significantly increased in mid luteal phase (1.70). After that it returned to the values observed in the early follicular phase.
  
  
  CONCLUSIONS
  Our results suggest the existence of an oestrogen vasodilatation effect on the central retinal artery that is menstrual phase-related and antagonized by progesterone.
authors.affiliation: Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Luiz Carlos
authors.initials: LC
authors.lastname: Viana
authors.forename: Marcos
authors.initials: M
authors.lastname: Faria
authors.forename: Heverton
authors.initials: H
authors.lastname: Pettersen
authors.forename: Marcos
authors.initials: M
authors.lastname: Sampaio
authors.forename: Selmo
authors.initials: S
authors.lastname: Geber
mesh_terms: D000293:Adolescent; D000328:Adult; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008597:Menstrual Cycle / Q000502:physiology*; D008875:Middle Aged; D011374:Progesterone / Q000494:pharmacology*; D011446:Prospective Studies; D011673:Pulsatile Flow / Q000187:drug effects*; D012161:Retinal Artery / Q000187:drug effects* / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D004967:Estrogens; D014665:Vasodilator Agents; D011374:Progesterone