title: The Effect of Body Position on Intraocular and Intracranial Pressure in Rabbits.
abstract: The correlation between cerebrospinal fluid (CSF) and intraocular pressure (IOP) is still unclear. We compared CSF and IOP measured by the same invasive technique using a new experimental model in rabbits during changes of body position.
  
  
  
  Pressure changes were recorded in the lateral ventricle (LV), the cortical subarachnoid space (CSS), and the anterior ocular chamber of anesthetized rabbits (n = 12). Animals and measuring instruments were both fixed on a board at an adequate hydrostatic level.
  
  
  
  In a horizontal position, control IOP (15.1 ± 1.6 cmH2O) and CSF pressure in the LV (12.4 ± 0.6 cmH2O) and CSS (12.2 ± 0.9 cmH2O) were similar during the 60-min period. When changing the body position from horizontal to vertical (upright), CSF pressures decreased drastically (LV = -5.5 ± 2.6 cmH2O and CSS = -7.7 ± 2.3 cmH2O), while the IOP decreased moderately (IOP = 13.3 ± 0.5 cmH2O).
  
  
  
  Change in body position from horizontal to vertical causes drastic changes in CSF pressure and moderate changes in IOP. Thus, IOP is not reflected by the CSF pressure. In an upright position, the values of CSF pressure were equal to the hydrostatic distance between measuring points and the foramen magnum, which suggests that CSF pressure inside the cranium depends on its anatomical and biophysical features, and not on CSF secretion and absorption.
authors.affiliation: Department of Pharmacology and the Croatian Institute for Brain Research, University of Zagreb School of Medicine, Šalata 11, Zagreb, HR-10 000, Croatia. mklarica@mef.hr.
authors.forename: Marijan
authors.initials: M
authors.lastname: Klarica
authors.affiliation: Department of Ophthalmology, University of Zagreb School of Medicine, University Hospital Center Zagreb, Zagreb, Croatia.
authors.forename: Tomislav
authors.initials: T
authors.lastname: Kuzman
authors.affiliation: Department of Pharmacology and the Croatian Institute for Brain Research, University of Zagreb School of Medicine, Šalata 11, Zagreb, HR-10 000, Croatia.
authors.forename: Ivana
authors.initials: I
authors.lastname: Jurjević
authors.affiliation: Department of Pharmacology and the Croatian Institute for Brain Research, University of Zagreb School of Medicine, Šalata 11, Zagreb, HR-10 000, Croatia.
authors.forename: Milan
authors.initials: M
authors.lastname: Radoš
authors.affiliation: Department of Pharmacology and the Croatian Institute for Brain Research, University of Zagreb School of Medicine, Šalata 11, Zagreb, HR-10 000, Croatia.
authors.forename: Ante
authors.initials: A
authors.lastname: Tvrdeić
authors.affiliation: Department of Molecular Biology, Rudjer Boskovic Institute, Zagreb, Croatia.
authors.forename: Darko
authors.initials: D
authors.lastname: Orešković
mesh_terms: D000818:Animals; D000867:Anterior Chamber; D005260:Female; D057446:Hydrodynamics; D007427:Intracranial Pressure / Q000502:physiology*; D007429:Intraocular Pressure / Q000502:physiology*; D020547:Lateral Ventricles; D008297:Male; D011187:Posture / Q000502:physiology*; D011817:Rabbits; D013346:Subarachnoid Space
keywords: Body position; Cerebrospinal fluid hydrodynamics; Cerebrospinal fluid pressure; Intraocular pressure