title: Diurnal fluctuation and concordance of intraocular pressure in glaucoma suspects and normal tension glaucoma patients.
abstract: OBJECTIVE
  The study objective was to determine the concordance of intraocular pressure (IOP) in glaucoma suspects (GS) and normal tension glaucoma (NTG) patients.
  
  
  METHODS
  This was a retrospective review of diurnal curves of untreated GS and NTG patients. No subject had IOP greater than 21 mm Hg. We defined GS patients as having suspicious optic nerves with normal visual fields, and NTG patients as having glaucomatous optic nerves with associated visual field loss. Goldmann applanation tonometry was performed at 10:00, 13:00, 16:00, 19:00, 22:00, and 07:00. Linear association of OD and OS IOP was estimated using Pearson correlation coefficient (r). The diurnal period was divided into 7 time intervals of 3, 6, 9, 12, 15, 18, and 21 hours, and the absolute difference in change in IOP between fellow eyes and probability that it was within 3 mm Hg were calculated.
  
  
  RESULTS
  The study included 68 GS and 95 NTG subjects. The diurnal curves of the OD and OS showed a parallel course in both groups. The average correlations (r) of OD and OS IOP over the 6 time points were 0.78 and 0.81 for GS and NTG, respectively. The mean absolute difference in IOP change between OD and OS over the 6 time intervals ranged between 1.4 and 1.9 mm Hg for GS, and 1.3 and 1.5 mm Hg for NTG subjects. The probability that this difference was within 3 mm Hg ranged between 87% and 94% for GS, and 86% and 93% for NTG subjects.
  
  
  CONCLUSIONS
  The diurnal variation in IOP between the 2 eyes in GS and NTG is largely concordant in approximately 90% of the time.
authors: Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
authors: Lesya M
authors: LM
authors: Shuba
authors: Andrew P
authors: AP
authors: Doan
authors: Michael K
authors: MK
authors: Maley
authors: M Bridget
authors: MB
authors: Zimmerman
authors: Robert B
authors: RB
authors: Dinn
authors: Emily C
authors: EC
authors: Greenlee
authors: Wallace L M
authors: WL
authors: Alward
authors: Young H
authors: YH
authors: Kwon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000503:physiopathology; D012189:Retrospective Studies; D014065:Tonometry, Ocular; D014786:Vision Disorders / Q000503:physiopathology; D014794:Visual Fields