title: The influence of posture change on ocular blood flow in normal subjects, measured by laser speckle flowgraphy.
abstract: OBJECTIVE
  To investigate, using laser speckle flowgraphy (LSFG), the autoregulation of ocular blood flow (BF) in response to posture change.
  
  
  METHODS
  This study comprised 20 healthy volunteers (mean age 30.0 ± 8.5). The mean blur rate (MBR) of the ocular circulation in the subjects was assessed in both a sitting and a supine position every 2 min over the course of 10 min. Baseline measurements of the MBR at the optic nerve head (ONH) and the choroid were taken in a sitting position. Increases in the MBR ratio in a supine position were calculated with reference to this baseline. Intraocular pressure (IOP), systemic blood pressure and heart rate in the brachial artery were also recorded.
  
  
  RESULTS
  In the ONH, the MBR ratio increased significantly over the baseline after 2 min (104.8 ± 5.0%, p = 0.001) and 4 min (104.4 ± 5.6%, p = 0.005), in a supine position, but decreased to the initial level after only 6 min. In the choroid, on the other hand, while the MBR ratio also increased significantly after 2 min in a supine position (113.7 ± 8.1%, p < 0.001), it kept this significant increase over the time course of 10 min. After 10 min in a supine position, IOP increased significantly (p < 0.001), systolic blood pressure decreased significantly (p < 0.001), but diastolic blood pressure did not change significantly compared to the baseline. (p = 0.07) CONCLUSIONS: ONH and choroidal circulation have significantly different hemodynamics in response to posture change in healthy volunteers. This finding suggests that LSFG enables us to assess the autoregulation of BF in the ONH.
authors: Department of Ophthalmology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
authors: Yukihiro
authors: Y
authors: Shiga
authors: Masahiko
authors: M
authors: Shimura
authors: Toshifumi
authors: T
authors: Asano
authors: Satoru
authors: S
authors: Tsuda
authors: Yu
authors: Y
authors: Yokoyama
authors: Naoko
authors: N
authors: Aizawa
authors: Kazuko
authors: K
authors: Omodaka
authors: Morin
authors: M
authors: Ryu
authors: Shunji
authors: S
authors: Yokokura
authors: Takayuki
authors: T
authors: Takeshita
authors: Toru
authors: T
authors: Nakazawa
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002829:Choroid / Q000098:blood supply*; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D017078:Laser-Doppler Flowmetry; D007834:Lasers; D008297:Male; D008833:Microcirculation / Q000502:physiology; D009898:Optic Disk / Q000098:blood supply*; D011187:Posture / Q000502:physiology*; D012016:Reference Values; D012039:Regional Blood Flow / Q000502:physiology*; D016683:Supine Position / Q000502:physiology; D055815:Young Adult