title: The ISNT rule and differentiation of normal from glaucomatous eyes.
abstract: OBJECTIVE
  To determine whether the ISNT rule (that normal eyes show a characteristic configuration for disc rim thickness of inferior > or = superior > or = nasal > or = temporal), widely used for clinical evaluation of the optic nerve head, can differentiate normal from glaucomatous eyes.
  
  
  METHODS
  All subjects underwent complete eye examination, including achromatic automated perimetry, simultaneous stereoscopic disc photography, and confocal scanning laser ophthalmoscopy. Subjects with normal eyes had no evidence of glaucoma or ocular hypertension and had normal perimetry measurements. Subjects with glaucoma had a reproducible visual field defect. One eye from each subject was randomly enrolled. The ISNT rule was assessed by masked evaluation of disc photographs at the 3, 6, 9, and 12 o'clock positions.
  
  
  RESULTS
  Sixty-six subjects with normal eyes (33 black and 33 white individuals) and 43 with open-angle glaucoma (15 black and 28 white individuals) were enrolled. The ISNT rule was intact in 52 (79%) of 66 normal eyes and 12 (28%) of 43 glaucomatous eyes (P<.001). Multiple logistic regression indicated that the odds ratio for glaucoma associated with violation of the ISNT rule was 6.04 (95% confidence interval, 1.74-20.95) after adjustment for age; race was not a confounder of this association.
  
  
  CONCLUSIONS
  The ISNT rule is useful in differentiating normal from glaucomatous optic nerves and is unaffected by race.
authors.affiliation: Department of Ophthalmology, The New York Eye and Ear Infirmary, New York University School of Medicine, New York, NY 10003, USA.
authors.forename: Noga
authors.initials: N
authors.lastname: Harizman
authors.forename: Cristiano
authors.initials: C
authors.lastname: Oliveira
authors.forename: Allen
authors.initials: A
authors.lastname: Chiang
authors.forename: Celso
authors.initials: C
authors.lastname: Tello
authors.forename: Michael
authors.initials: M
authors.lastname: Marmor
authors.forename: Robert
authors.initials: R
authors.lastname: Ritch
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Liebmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044383:Black People; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000208:ethnology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis / Q000208:ethnology; D016017:Odds Ratio; D009887:Ophthalmoscopy; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000208:ethnology; D010781:Photography; D011446:Prospective Studies; D014065:Tonometry, Ocular; D058609:Visual Field Tests; D044465:White People