title: Optic disc torsion direction predicts the location of glaucomatous damage in normal-tension glaucoma patients with myopia.
abstract: OBJECTIVE
  To characterize optic disc tilt and torsion in normal-tension glaucoma (NTG) patients with myopia and to evaluate the relationship between optic disc tilt and torsion with the location of visual field (VF) defect.
  
  
  METHODS
  Retrospective, case-control design.
  
  
  METHODS
  Two hundred twenty-five NTG patients.
  
  
  METHODS
  Patients were divided into a myopic NTG group (spherical equivalent more than -2.00 diopters [D] or axial length more than 24.0 mm; n = 166) and nonmyopic NTG group (spherical equivalent less than -0.50 D or axial length less than 24.0 mm; n = 59). Disc tilt, which was identified by the tilt ratio, disc torsion, and area of peripapillary atrophy (PPA), was measured from disc photographs. Patients were divided further into superior and inferior defect groups according to the location of the VF defect in the pattern deviation map. Logistic regression analysis was used to determine the relationship between ocular factors, including tilt ratio, torsion degree, and the VF defect location.
  
  
  METHODS
  Tilt ratio, torsion degree, PPA area, and location of VF defect.
  
  
  RESULTS
  Among 225 NTG eyes, 166 (73.8%) were myopic eyes. The myopic NTG group was significantly younger (42.85 years) than the nonmyopic NTG group (60.73 years). Disc tilt (45.8%) and torsion (75.9%) were significantly more prevalent in the myopic NTG group than in the nonmyopic NTG group. Although just short of statistical significance (P = 0.057), PPA area was larger in the myopic NTG group. The VF defect location was significantly different between the 2 groups, with superior defects more prevalent in the myopic NTG group (69.9%; P<0.001). Torsion degree was significantly different in the superior defect group (18.45°) compared with the inferior defect group (-3.81°; P = 0.001). Torsion degree was the only factor related to VF defect location in both univariate (P = 0.001) and multivariate (P = 0.014) logistic regression analyses.
  
  
  CONCLUSIONS
  Korean NTG patients had a high prevalence of myopia and young age. Optic disc tilt and torsion were highly prevalent in Korean NTG patients with myopia. The direction of the optic disc torsion may predict the location of damage.
authors.affiliation: Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Hae-Young L
authors.initials: HY
authors.lastname: Park
authors.forename: Kook
authors.initials: K
authors.lastname: Lee
authors.forename: Chan Kee
authors.initials: CK
authors.lastname: Park
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007429:Intraocular Pressure / Q000502:physiology; D057066:Low Tension Glaucoma / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000150:complications* / Q000453:epidemiology; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000453:epidemiology; D010781:Photography; D015995:Prevalence; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D014102:Torsion Abnormality / Q000175:diagnosis* / Q000453:epidemiology; D014786:Vision Disorders / Q000175:diagnosis; D058609:Visual Field Tests; D014794:Visual Fields