The effect of lateral decubitus position on intraocular pressure in patients with untreated open-angle glaucoma

Purpose: To investigate the effect of change of body posture from the supine to the lateral decubitus position on intraocular pressure (IOP) in patients with open-angle glaucoma. Design: Prospective, observational case series. Methods: Setting. Institutional. Participants. Forty-four eyes of 22 patients with newly diagnosed bilateral open-angle glaucoma. Observation procedures. IOP was measured using the Tono-Pen XL (Reichert Inc) in both eyes 10 minutes after assuming each position: sitting, supine, right lateral decubitus, supine, left lateral decubitus, and supine. By comparing the mean deviation (MD) of Humphrey visual field between both eyes of a patient, eyes were classified into either worse-MD eye or better-MD eye. Main outcome measures. Magnitude of IOP alterations by postural changes and intereye difference of IOP with each posture. Results: The mean ± SD IOP of the dependent eyes (eye on the lower side in the lateral decubitus position) increased after changing from the supine to the right lateral decubitus position (19.1 ± 2.6 mm Hg vs 21.0 ± 2.7 mm Hg; P =.019) or the left lateral decubitus position (18.6 ± 2.9 mm Hg vs 20.6 ± 3.1 mm Hg; P =.002). The mean IOP of the dependent eyes was significantly higher than that of the nondependent eyes in the lateral decubitus positions (right lateral decubitus, +1.2 mm Hg; left lateral decubitus, +1.6 mm Hg; both, P <.05). Compared with the better-MD eyes, the worse-MD eyes showed a tendency for greater IOP rise with positional change from the supine to lateral decubitus position (2.3 ± 2.2 mm Hg vs 1.5 ± 2.1 mm Hg; P =.065). Conclusions: The postural change from the supine to lateral decubitus position may increase the IOP of the dependent eyes in patients with open-angle glaucoma.