title: Optic nerve sheath diameter in normal-tension glaucoma patients.
abstract: BACKGROUND
  To report on the optic nerve sheath diameter (ONSD) in patients with normal-tension glaucoma (NTG) compared with controls without known optic nerve (ON) or intracranial disease.
  
  
  METHODS
  In 18 patients with NTG (mean age 64.9 ± 8.9 years; 7 women and 11 men), CT of the orbit was performed. 17 age- and gender-matched patients without ON or intracranial disease, who underwent CT of the orbits for non-ophthalmological reasons, served as controls. The widest intraorbital ONSD in axial sections was measured using a standardised technique.
  
  
  METHODS
  unmasked. Statistical analysis was performed using an independent two-tailed t Test and the non-parametric Spearman correlation test.
  
  
  RESULTS
  ONSD was significantly (p<0.001) increased in NTG patients (right side: mean 7.9 ± 0.9 mm SD; left: 8.0 ± 1.1 mm) compared with controls (right: 6.3 ± 0.5 mm; left: 6.1 ± 0.6 mm). Neither the NTG nor the control group had a significant difference in ONSD between males and females or between right and left sides.
  
  
  CONCLUSIONS
  An increased ONSD is generally associated with increased intracranial pressure; however, ONSDs in a group of NTG patients also were significantly increased compared with controls. ON sheath compartmentation and thinning of the ON sheath are two possible explanations for an increase in the ONSD in patients with NTG.
authors.affiliation: Department of Ophthalmology, Kantonsspital Aarau, Switzerland.
authors.forename: Gregor Peter
authors.initials: GP
authors.lastname: Jaggi
authors.forename: Neil Richard
authors.initials: NR
authors.lastname: Miller
authors.forename: Josef
authors.initials: J
authors.lastname: Flammer
authors.forename: Robert N
authors.initials: RN
authors.lastname: Weinreb
authors.forename: Luca
authors.initials: L
authors.lastname: Remonda
authors.forename: Hanspeter Esriel
authors.initials: HE
authors.lastname: Killer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005902:Glaucoma, Open-Angle / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D007427:Intracranial Pressure; D057066:Low Tension Glaucoma / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009186:Myelin Sheath / Q000000981:diagnostic imaging* / Q000473:pathology; D009898:Optic Disk / Q000000981:diagnostic imaging* / Q000473:pathology; D009900:Optic Nerve / Q000000981:diagnostic imaging* / Q000473:pathology; D009915:Orbit / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*