title: Glaucoma patients demonstrate faulty autoregulation of ocular blood flow during posture change.
abstract: OBJECTIVE
  Autoregulation of blood flow during posture change is important to ensure consistent organ circulation. The purpose of this study was to compare the change in retrobulbar ocular blood flow in glaucoma patients with normal subjects during supine and upright posture.
  
  
  METHODS
  20 open angle glaucoma patients and 20 normal subjects, similar in age and sex distribution, were evaluated. Blood pressure, intraocular pressure, and retrobulbar blood velocity were tested after 30 minutes of sitting and again after 30 minutes of lying. Retrobulbar haemodynamic measures of peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) were obtained in the ophthalmic and central retinal arteries using colour Doppler imaging (CDI).
  
  
  RESULTS
  When changing from the upright to supine posture, normal subjects demonstrated a significant increase in OA EDV (p = 0.016) and significant decrease in OA RI (p = 0.0006) and CRA RI (p = 0.016). Glaucoma patients demonstrated similar changes in OA measures of EDV (p = 0.02) and RI (p = 0.04), but no change in CRA measures.
  
  
  CONCLUSIONS
  Glaucoma patients exhibit faulty autoregulation of central retinal artery blood flow during posture change.
authors.affiliation: Department of Ophthalmology, Indiana University, Indianapolis, IN, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Evans
authors.forename: A
authors.initials: A
authors.lastname: Harris
authors.forename: M
authors.initials: M
authors.lastname: Garrett
authors.forename: H S
authors.initials: HS
authors.lastname: Chung
authors.forename: L
authors.initials: L
authors.lastname: Kagemann
mesh_terms: D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D005901:Glaucoma / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006706:Homeostasis; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009915:Orbit / Q000098:blood supply*; D011187:Posture / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D018615:Ultrasonography, Doppler, Color