title: Changes in intraocular pressure in anesthetized prone patients.
abstract: BACKGROUND
  Postoperative visual loss occurs more commonly in patients placed prone. The mechanism may be raised intraocular pressure (IOP) causing an ischemic oculopathy.
  
  
  METHODS
  IOP was measured in 20 patients undergoing spinal surgery. The IOP was measured prior to intubation, immediately after pronation, and at the end of surgery before the patient was returned to the supine position. Duration of surgery, method of head stabilization and standard physiological parameters were recorded.
  
  
  RESULTS
  Both measurements of median IOP in the prone position were significantly higher than that in the supine position (P < 0.001). There was no evidence of a relationship between rise in IOP and duration of surgery, age, or body mass index. There was weak evidence of a tendency for patients whose heads were on pillows to have higher values of IOP at the end of surgery than patients whose heads were supported in pins.
  
  
  CONCLUSIONS
  IOP increases when anesthetized patients are placed in the prone position.
authors.affiliation: Department of Anaesthesia, National Hospital for Neurology and Neurosurgery, London, UK. Kath.Hunt@dial.pipex.com
authors.forename: Katharine
authors.initials: K
authors.lastname: Hunt
authors.forename: Rahul
authors.initials: R
authors.lastname: Bajekal
authors.forename: Ian
authors.initials: I
authors.lastname: Calder
authors.forename: Rosanne
authors.initials: R
authors.lastname: Meacher
authors.forename: Joseph
authors.initials: J
authors.lastname: Eliahoo
authors.forename: James F
authors.initials: JF
authors.lastname: Acheson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D000768:Anesthesia, General; D015992:Body Mass Index; D004487:Edema / Q000453:epidemiology; D005145:Face; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures; D011183:Postoperative Complications / Q000453:epidemiology; D016684:Prone Position / Q000502:physiology*; D012149:Restraint, Physical; D013131:Spine / Q000601:surgery; D016683:Supine Position / Q000502:physiology