title: Long-term intraocular pressure fluctuations and risk of conversion from ocular hypertension to glaucoma.
abstract: OBJECTIVE
  To investigate whether long-term intraocular pressure (IOP) fluctuations are a risk factor for conversion from ocular hypertension to glaucoma.
  
  
  METHODS
  Observational cohort study.
  
  
  METHODS
  The study included 252 eyes of 126 patients with ocular hypertension observed untreated as part of the Diagnostic Innovations in Glaucoma Study. At baseline, ocular hypertensive eyes had elevated IOP, normal visual fields (VFs) on standard automated perimetry, and normal optic discs as evaluated by stereophotograph assessment.
  
  
  METHODS
  Glaucoma conversion was defined as development of reproducible VF loss or optic disc damage. Analyses included all IOP measurements from the baseline visit to time of progression (for converters) and last follow-up (for nonconverters). Mean IOP and IOP fluctuation were calculated as the arithmetic mean and standard deviation (SD), respectively, of all available IOP measurements per eye.
  
  
  METHODS
  Univariable and multivariable Cox regression analyses were used to evaluate the association between IOP fluctuation and time to progression. Multivariable models adjusted for age, mean IOP, central corneal thickness, vertical cup-to-disc ratio, and pattern SD.
  
  
  RESULTS
  Forty eyes of 31 subjects developed glaucoma during follow-up. Mean IOPs during follow-up were 25.4+/-4.2 mmHg for the eyes that converted to glaucoma and 24.1+/-3.5 mmHg for the eyes that did not. Corresponding values for IOP fluctuation were 3.16+/-1.35 mmHg and 2.77+/-1.11 mmHg, respectively. Intraocular pressure fluctuation was not a risk factor for conversion to glaucoma both in univariable analysis (hazard ratio [HR], 1.30 per 1 mmHg higher; 95% confidence interval [CI], 0.76-1.96; P = 0.092) and in multivariable analysis (adjusted HR, 1.08 per 1 mmHg higher; 95% CI, 0.79-1.48; P = 0.620). Mean IOP during follow-up was a significant risk factor for progression both in univariable analysis (HR = 1.16 per 1 mmHg higher; 95% CI, 1.04-1.31; P = 0.010) and in multivariable analysis (adjusted HR, 1.20 per 1 mmHg higher; 95% CI, 1.06-1.36; P = 0.005).
  
  
  CONCLUSIONS
  Long-term IOP fluctuations do not appear to be significantly associated with the risk of developing glaucoma in untreated ocular hypertensive subjects.
authors.affiliation: Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California 92093-0946, USA. fmedeiros@eyecenter.ucsd.edu
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Medeiros
authors.forename: Robert N
authors.initials: RN
authors.lastname: Weinreb
authors.forename: Linda M
authors.initials: LM
authors.lastname: Zangwill
authors.forename: Luciana M
authors.initials: LM
authors.lastname: Alencar
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Sample
authors.forename: Cristiana
authors.initials: C
authors.lastname: Vasile
authors.forename: Christopher
authors.initials: C
authors.lastname: Bowd
mesh_terms: D015331:Cohort Studies; D016001:Confidence Intervals; D023381:Endpoint Determination; D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis / Q000209:etiology*; D016016:Proportional Hazards Models; D012307:Risk Factors; D014786:Vision Disorders / Q000175:diagnosis / Q000209:etiology*; D058609:Visual Field Tests; D014794:Visual Fields