title: Head-down Posture in Glaucoma Suspects Induces Changes in IOP, Systemic Pressure, and PERG That Predict Future Loss of Optic Nerve Tissue.
abstract: OBJECTIVE
  To obtain pilot data on posture-induced changes of intraocular pressure (IOP), systemic pressure, and pattern electroretinogram (PERG) predictive of future optic nerve tissue loss glaucoma suspects (GSs).
  
  
  METHODS
  Mean peripapillary retinal fiber layer thickness (RNFLT) was measured with optical coherence tomography 2 times/year in 28 GS aged 58±8.9 years over 5.0±0.73 years. All patients had a baseline PERG, IOP, and brachial blood pressure measurements in the seated and -10 degrees head-down-body-tilt (HDT) position. Outcome measures were seated/HDT PERG amplitude and phase, IOP, mean arterial blood pressure, and estimated ocular perfusion pressure. An additional group of 11 similarly aged controls aged 56.9±13 years was tested for comparison.
  
  
  RESULTS
  Although all GS had initial RNFLT in the normal range, 9/28 of them developed significant (P<0.05) loss of mean RNFLT [thinners (T)] over the follow-up period as opposed to 19/28 who did not [nonthinners (NT)]. Significant (P<0.05) differences between similarly aged controls, NT, and T were found in PERG amplitude, PERG phase, mean arterial blood pressure, IOP, and ocular perfusion pressure. A nominal logistic regression using baseline PERG and hemodynamic variables was able to distinguish T from NT with an area under receiving operator characteristic of 0.89 (SE, 0.07).
  
  
  CONCLUSIONS
  Baseline PERG, IOP, and systemic blood pressure, together with their changes upon HDT, may have predictive value for future loss of optic nerve tissue in GS. This study supports the rationale for a full-scale clinical trial to identify patients at high risk of development of glaucoma.
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Porciatti
authors.forename: William J
authors.initials: WJ
authors.lastname: Feuer
authors.forename: Pedro
authors.initials: P
authors.lastname: Monsalve
authors.forename: Giacinto
authors.initials: G
authors.lastname: Triolo
authors.forename: Luis
authors.initials: L
authors.lastname: Vazquez
authors.forename: John
authors.initials: J
authors.lastname: McSoley
authors.forename: Lori M
authors.initials: LM
authors.lastname: Ventura
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D004596:Electroretinography; D005260:Female; D018475:Head-Down Tilt / Q000502:physiology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009798:Ocular Hypertension / Q000503:physiopathology*; D009901:Optic Nerve Diseases / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular