IOP variations in the sitting and supine positions.

PURPOSE 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.