title: Ultrasound measurement of optic nerve diameter and optic nerve sheath diameter in healthy Chinese adults.
abstract: BACKGROUND
  Measurement of optic nerve sheath diameter (ONSD) is a fast and non-invasive method in detecting elevated intracranial pressure. However, the reported normal range of ONSD was inconsistent. The objective of the study was to determine the normal range of ONSD in healthy Chinese adults.
  
  
  METHODS
  Eyeball transverse diameter (ETD), optic nerve diameter (OND), and ONSD were measured by ultrasound examination in healthy adult volunteers. The OND and ONSD were assessed 3 mm behind the globe. The section showing maximal transverse diameter of the eyeball was frozen and the diameter was measured. Each ETD, OND and ONSD was examined twice and the mean value was calculated.
  
  
  RESULTS
  A total of 519 healthy volunteers were included in the study. The median (interquartile range) of ETD, OND and ONSD were 22.3 (21.6 to 23.1) mm, 3.2 (2.9 to 3.4) mm, and 5.1 (4.7 to 5.4) mm, respectively. The 95% percentile of ONSD was 5.9 mm. There was no significant difference in ETD, OND or ONSD between male and female, or between left and right eye. ONSD was significantly correlated with OND (r = 0.62, P < 0.001), and the median OND/ONSD ratio (interquartile range) was 0.63 (0.59 to 0.67).
  
  
  CONCLUSIONS
  The median and the 95% percentile of sonographic measurement of ONSD are 5.1 mm and 5.9 mm in healthy Chinese adults. The ONSD is correlated with OND, while independent of gender, age, height, weight and ETD. The median OND/ONSD ratio is 0.63 and this parameter warrants further investigation in patients with brain injury.
authors.affiliation: Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, No 6, TiantanXili, Dongcheng District, Beijing, 100050, China. baojr2@163.com.|Surgical Intensive Care Unit, Fujian Provincial Clinical College, Fujian Medical University, No. 134, Dongjie Street, Gulou District, Fuzhou, Fujian, 350001, China. baojr2@163.com.
authors.forename: Han
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Ultrasonography, Fujian Provincial Clinical College, Fujian Medical University, No. 134, Dongjie Street, Gulou District, 350001, Fuzhou, Fujian, China. 470545763@qq.com.
authors.forename: Gui-Sheng
authors.initials: GS
authors.lastname: Ding
authors.affiliation: Department of Ultrasonography, Fujian Provincial Clinical College, Fujian Medical University, No. 134, Dongjie Street, Gulou District, 350001, Fuzhou, Fujian, China. zhaohan121@163.com.
authors.forename: Yan-Chun
authors.initials: YC
authors.lastname: Zhao
authors.affiliation: Surgical Intensive Care Unit, Fujian Provincial Clinical College, Fujian Medical University, No. 134, Dongjie Street, Gulou District, Fuzhou, Fujian, 350001, China. garyyrg@yahoo.com.
authors.forename: Rong-Guo
authors.initials: RG
authors.lastname: Yu
authors.affiliation: Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, No 6, TiantanXili, Dongcheng District, Beijing, 100050, China. zhoujx.cn@icloud.com.
authors.forename: Jian-Xin
authors.initials: JX
authors.lastname: Zhou
mesh_terms: D000328:Adult; D044466:Asian People; D005260:Female; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D014463:Ultrasonography