title: Optic nerve sheath diameters in healthy adults measured by computer tomography.
abstract: OBJECTIVE
  To measure optic nerve sheath diameters (ONSD) in different locations by computer tomography (CT) and to recommend the best location for cases when ONSD is used for intracranial pressure monitoring.
  
  
  METHODS
  In a prospective cohort study, CT data of 300 healthy adults were analyzed (600 eyes). In all cases, the CT investigation was performed at the Emergency Department because of the various conditions that proved not to be connected with ophthalmological or neurological pathology. The ONSD were measured at 3 mm and 8 mm distance from the globe, and 3 mm from the anterior opening of the optic canal. The correlation analysis was performed with gender, age, and ethnic background.
  
  
  RESULTS
  The right/left ONSD are 4.94±1.51/5.17±1.34 mm at 3 mm, 4.35±0.76/4.45±0.62 mm at 8 mm from the globe, and 3.55±0.82/3.65±0.7 mm at 3 mm from the optic canal. No significant differences correlated with gender of the patients, their age, and ethnic background were found.
  
  
  CONCLUSIONS
  In healthy persons, the ONSD varies from 5.17±1.34 mm to 3.55±0.82 mm in different locations within the intraorbital space. The most stable results with lesser standard deviation can be obtained if it is measured 8-10 mm from the globe.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Assaf Harofe Medical Center, Affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin 70300, Israel.
authors.forename: Michael
authors.initials: M
authors.lastname: Vaiman
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Assaf Harofe Medical Center, Affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin 70300, Israel.
authors.forename: Rani
authors.initials: R
authors.lastname: Abuita
authors.affiliation: Department of Radiology, Assaf Harofe Medical Center, Affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin 70300, Israel.
authors.forename: Inessa
authors.initials: I
authors.lastname: Bekerman
keywords: computer tomography; intracranial pressure; optic nerve sheath