title: Compromised autoregulatory control of ocular hemodynamics in glaucoma patients after postural change.
abstract: OBJECTIVE
  The autoregulatory control of retrobulbar blood flow in response to postural challenge was investigated in normal-tension glaucoma (NTG) patients in comparison with primary open-angle glaucoma (POAG) patients and healthy volunteers.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Twenty POAG patients, 20 NTG patients, and 20 control subjects.
  
  
  METHODS
  Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistivity index (RI) in the short posterior ciliary artery (SPCA), central retinal artery (CRA) and ophthalmic artery (OA) were recorded after a change from sitting upright to a supine body position using color Doppler imaging.
  
  
  METHODS
  Peak systolic velocity, EDV, and RI.
  
  
  RESULTS
  Ten minutes after postural change to a supine position, blood flow velocities in the SPCA remained unchanged in controls, whereas a significant increase of PSV and EDV was found in both glaucoma groups. The RI in the SPCA was significantly lowered in the NTG group. Recordings for the OA and CRA showed a significant increase in EDV and significant decrease in RI in all 3 groups; a significant increase in PSV in the CRA was detected only in the NTG group.
  
  
  CONCLUSIONS
  The unaltered flow velocities in the SPCA of healthy controls may indicate tight autoregulatory control, whereas the flow velocities in the CRA and OA appeared to follow alterations in hydrostatic pressure. In contrast, NTG and POAG patients demonstrated an insufficient compensatory response to postural change, leading to accelerated flow in the SPCA. This compromised autoregulatory control could represent another contributing factor in the pathogenesis of glaucoma.
authors.affiliation: Glaukomlabor, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Galambos
authors.forename: Joanna
authors.initials: J
authors.lastname: Vafiadis
authors.forename: Silvia E
authors.initials: SE
authors.lastname: Vilchez
authors.forename: Lars
authors.initials: L
authors.lastname: Wagenfeld
authors.forename: Eike T
authors.initials: ET
authors.lastname: Matthiessen
authors.forename: Gisbert
authors.initials: G
authors.lastname: Richard
authors.forename: Maren
authors.initials: M
authors.lastname: Klemm
authors.forename: Oliver
authors.initials: O
authors.lastname: Zeitz
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D019842:Ciliary Arteries / Q000000981:diagnostic imaging / Q000502:physiology; D005260:Female; D005902:Glaucoma, Open-Angle / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006439:Hemodynamics; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009880:Ophthalmic Artery / Q000000981:diagnostic imaging / Q000502:physiology; D009898:Optic Disk / Q000098:blood supply*; D011187:Posture; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000502:physiology; D012161:Retinal Artery / Q000000981:diagnostic imaging / Q000502:physiology; D018615:Ultrasonography, Doppler, Color