title: Ocular rigidity, ocular pulse amplitude, and pulsatile ocular blood flow: the effect of axial length.
abstract: OBJECTIVE
  Previous studies have shown a negative correlation between axial length (AL) and pulsatile ocular blood flow (POBF). This relation has been questioned because of the possible confounding effect of ocular volume on ocular rigidity (OR). The purpose of this study was to investigate the relation between AL, as a surrogate parameter for ocular volume, and OR, ocular pulse amplitude (OPA), and POBF.
  
  
  METHODS
  Eighty-eight cataract patients were enrolled in this study. A computer-controlled device comprising a microdosimetric pump and a pressure sensor was used intraoperatively. The system was connected to the anterior chamber and used to raise the intraocular pressure (IOP) from 15 to 40 mm Hg, by infusing the eye with a saline solution. After each infusion step, the IOP was continuously recorded for 2 seconds. Blood pressure and pulse rate were measured during the procedure. The OR coefficient was calculated from the pressure volume data. OPA and POBF were measured from pressure recordings.
  
  
  RESULTS
  Median AL was 23.69 (interquartile range 3.53) mm. OR coefficient was 0.0218 (0.0053) μL(-1). A negative correlation between the OR coefficient and AL (ρ = -0.641, P < 0.001) was documented. Increasing AL was associated with decreased OPA (ρ = -0.637, P < 0.001 and ρ = -0.690, P < 0.001) and POBF (ρ = -0.207, P = 0.053 and ρ = -0.238, P = 0.028) at baseline and elevated IOP, respectively.
  
  
  CONCLUSIONS
  Based on manometric data, increasing AL is associated with decreased OR, OPA, and POBF. These results suggest decreased pulsatility in high myopia and may have implications on ocular pulse studies and the pathophysiology of myopia.
authors: Ophthalmology Department, University Hospital of Larissa, Greece. anna.dastiridou@gmail.com
authors: Anna I
authors: AI
authors: Dastiridou
authors: Harilaos
authors: H
authors: Ginis
authors: Miltiadis
authors: M
authors: Tsilimbaris
authors: Nikos
authors: N
authors: Karyotakis
authors: Efstathios
authors: E
authors: Detorakis
authors: Charalambos
authors: C
authors: Siganos
authors: Pierros
authors: P
authors: Cholevas
authors: Evangelia E
authors: EE
authors: Tsironi
authors: Ioannis G
authors: IG
authors: Pallikaris
mesh_terms: D000368:Aged; D058452:Axial Length, Eye / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D002386:Cataract / Q000503:physiopathology*; D004547:Elastic Tissue / Q000502:physiology*; D005123:Eye / Q000033:anatomy & histology* / Q000098:blood supply; D005260:Female; D006339:Heart Rate; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009799:Ocular Physiological Phenomena; D011673:Pulsatile Flow / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D012044:Regression Analysis; D014065:Tonometry, Ocular