title: IOP variations in the sitting and supine positions.
abstract: OBJECTIVE
  The aim of this study was to assess the influence of the position (upright vs. supine) in the intraocular pressure (IOP) measured with a non-contact portable tonometer.
  
  
  METHODS
  Fifty university students with a mean age of 22.3±4.2 years (mean±SD) were recruited to participate in this study. IOP was measured with the non-contact tonometer Keeler, Pulsair EasyEye. Measurements in upright and supine positions were randomly obtained. In the upright position, 2 series of 3 measures (UP1 and UP2) and a series of 3 measures in the supine position were performed.
  
  
  RESULTS
  The values obtained in the positions UP1 and UP2 were compared, as well as the values of the upright and supine positions. No statistically significant differences were found when comparing the values obtained in the upright position (P>0.05). Instead, when the subjects were in the supine position, IOP increased 2.47±2.12 mm Hg (mean±SD), as opposed to the value obtained in the upright position (P<0.001).
  
  
  CONCLUSIONS
  Results from this study showed that IOP increased when measured in the supine position and that the Pulsair EasyEye tonometer can determine those variations in a healthy young population.
authors.affiliation: Clinical and Experimental Optometry Research Lab, Department of Physics (Optometry), School of Sciences, University of Minho, Braga, Portugal. jorge@fisica.uminho.pt
authors.forename: Jorge
authors.initials: J
authors.lastname: Jorge
authors.forename: Rui
authors.initials: R
authors.lastname: Ramoa-Marques
authors.forename: Adelaide
authors.initials: A
authors.lastname: Lourenço
authors.forename: Sandra
authors.initials: S
authors.lastname: Silva
authors.forename: Sérgio
authors.initials: S
authors.lastname: Nascimento
authors.forename: António
authors.initials: A
authors.lastname: Queirós
authors.forename: José M
authors.initials: JM
authors.lastname: Gonzalez-Méijome
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D011187:Posture / Q000502:physiology*; D016684:Prone Position; D016683:Supine Position; D014065:Tonometry, Ocular; D055815:Young Adult