title: Associations between intracranial pressure, intraocular pressure and mean arterial pressure in patients with traumatic and non-traumatic brain injuries.
abstract: BACKGROUND
  Anatomical proximity of the eye and the intracranial space is a fact but the existence of physiological and pathophysiological relationships between them is elusive. The objective of this study was to explore anatomical and pathophysiological interactions between the eye and the intracranial space and to assess clinical utility of intraocular pressure measurement in estimation of intracranial pressure in patients with brain injuries and to discover how haemodynamic instability could influence these interactions. Controversy surrounds the recent literature concerning this problem and the consensus has not been achieved.
  
  
  METHODS
  We evaluated the correlation between intracranial pressure and intraocular pressure, intracranial pressure and mean arterial pressure, intraocular pressure and mean arterial pressure in 40 patients with brain injuries initially comatose, admitted to our hospital. All patients required the intracranial pressure monitoring on clinical grounds. Simultaneous recordings of intracranial pressure, intraocular pressure and mean arterial pressure were performed.
  
  
  RESULTS
  We calculated both the linear correlation coefficient and the Spearman rank-order correlation coefficient for all three relations. We found significant correlation between intraocular pressure and mean arterial pressure in 63% of the tested population. When the power of the test was increased, by considering only patients with 11 or more observations, this ratio increased to 76%. However, the correlation between intraocular pressure and intracranial pressure, as well as, between intracranial pressure and mean arterial pressure was not significant.
  
  
  CONCLUSIONS
  There is no anatomical and pathophysiological basis for the statement that intraocular pressure can be used as an indirect estimator of intracranial pressure.
authors.affiliation: Department of Anaesthesia and Critical Care, Regional Medical Centre, Aleja Witosa 26, 45-418 Opole, Poland. antocz@mp.pl
authors.forename: Tomasz
authors.initials: T
authors.lastname: Czarnik
authors.forename: Ryszard
authors.initials: R
authors.lastname: Gawda
authors.forename: Waldemar
authors.initials: W
authors.lastname: Kolodziej
authors.forename: Dariusz
authors.initials: D
authors.lastname: Latka
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Sznajd-Weron
authors.forename: Rafal
authors.initials: R
authors.lastname: Weron
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D001930:Brain Injuries / Q000503:physiopathology*; D003128:Coma / Q000503:physiopathology; D005260:Female; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology*; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D014065:Tonometry, Ocular; D055815:Young Adult