title: Incidence of elevation of intraocular pressure over time and associated factors in normal-tension glaucoma.
abstract: OBJECTIVE
  The authors determine whether intraocular pressure (IOP) increases to levels that challenge the diagnosis of normal-tension glaucoma (NTG) and determine clinical factors associated with the IOP elevation.
  
  
  METHODS
  Forty patients with NTG who met the following enrollment criteria were selected: IOPs less than 21 mm Hg during initial 24-hour pressure curve and throughout the subsequent 12 months; examined every 1 to 4 months for at least 4 years; and no ocular hypotensive treatment. The eye with the higher mean IOP during the initial 24-hour pressure curve was selected from each patient. The observation period ranged from 4.0 years to 7.8 years (mean, 5.2 years). Significant IOP elevation was defined as a significant increase (p < 0.05) of IOP over time, determined by Spearman rank correlation coefficient method. The IOP elevation was correlated to clinical factors by means of a logistic multiple regression analysis (LOGIST procedure using PC-SAS, SAS Institute, Inc. Cary, NC, U.S.A.).
  
  
  RESULTS
  Eleven eyes were rated positive for IOP elevation. The regression model demonstrated that maximum IOP during the initial 24-hour pressure curve and the development of disc hemorrhage (DH) were significantly correlated with IOP elevation (p = 0.006 and p = 0.049, respectively). The odds ratios calculated were 1.98 per 1 mm Hg rise of maximum IOP during the initial 24-hour pressure curve and 6.54 for positive DH.
  
  
  CONCLUSIONS
  Intraocular pressure might increase in NTG eyes following the initial diagnosis. A higher maximum IOP during initial 24-hour pressure curve and the development of DH during follow-up was significantly associated with subsequent IOP elevation in NTG patients.
authors.affiliation: Department of Ophthalmology, Gifu University School of Medicine, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Oguri
authors.forename: S
authors.initials: S
authors.lastname: Sogano
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Kitazawa
mesh_terms: D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D015994:Incidence; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000209:etiology* / Q000503:physiopathology; D012044:Regression Analysis; D012189:Retrospective Studies; D013997:Time Factors; D014065:Tonometry, Ocular