title: Circadian changes in subfoveal choroidal thickness and the relationship with circulatory factors in healthy subjects.
abstract: OBJECTIVE
  To investigate circadian changes in subfoveal choroidal thickness (SFCT) and the relation to systemic factors in healthy subjects.
  
  
  METHODS
  Thirty-eight eyes of 19 healthy volunteers were enrolled. SFCT was measured by using prototype high-penetration optical coherence tomography. Intraocular pressure (IOP), systolic blood pressure (SBP), diastolic blood pressures (DBP), and heart rate (HR) were measured every 3 hours over a 24-hour period. Circadian changes in the mean arterial pressure (MAP) and mean ocular perfusion pressure (MOPP) were calculated. The difference between the maximal and minimal SFCTs was analyzed, and correlations between the SFCT and other systemic factors were evaluated.
  
  
  RESULTS
  There was a significant circadian variation in SFCT (P < 0.0001). The total mean SFCT was 280.3 ± 106.1 μm. At 6 PM, the mean SFCT (271.9 ± 103.5 μm) was the thinnest and at 3 AM it was the thickest (290.8 ± 110.8 μm). The SFCTs in 32 of 38 eyes were thickest between 3 and 9 AM and in 27 of 38 eyes, thinnest between 3 and 9 PM. The mean SFCT was significantly negatively correlated with the mean SBP (R(2) = 0.59, P = 0.02) in all eyes. There were no significant correlations between the mean SFCT and the mean DBP, MAP, HR, IOP, and MOPP in all eyes.
  
  
  CONCLUSIONS
  We investigated the circadian change of choroidal thickness using high-penetration optical coherence tomography in healthy volunteers. The significant diurnal change was found and the choroid was thicker at night and thinner in daytime. Fluctuations in the choroidal thickness may be related to SBP.
authors.affiliation: National Hospital Organization, Osaka National Hospital, Osaka, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Usui
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ikuno
authors.forename: Masahiro
authors.initials: M
authors.lastname: Akiba
authors.forename: Ichiro
authors.initials: I
authors.lastname: Maruko
authors.forename: Tetsuju
authors.initials: T
authors.lastname: Sekiryu
authors.forename: Kohji
authors.initials: K
authors.lastname: Nishida
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Iida
mesh_terms: D000328:Adult; D001699:Biometry; D001794:Blood Pressure / Q000502:physiology*; D002829:Choroid / Q000033:anatomy & histology*; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005584:Fovea Centralis; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D041623:Tomography, Optical Coherence; D055815:Young Adult