Effect of Lateral Decubitus Position on Intraocular Pressure in Glaucoma Patients with Asymmetric Visual Field Loss

Abstract

To investigate the effect of the lateral decubitus position (LDP) on intraocular pressure (IOP) in glaucoma patients with asymmetric visual field loss. Prospective, cross-sectional study. Ninety-eight eyes of 49 consecutive bilateral glaucoma patients with asymmetric visual field loss, divided into better eye and worse eye groups for calculation of mean deviation. Intraocular pressure was measured using a Goldmann applanation tonometer and rebound tonometer (Icare PRO; Icare Finland Oy, Helsinki, Finland) in each of the following positions: sitting, supine, right LDP, and left LDP. Visual field was examined using the Humphrey Field Analyzer (HFA II; Carl Zeiss Meditec, Dublin, CA). A questionnaire on the preferred lying position during sleep was administered to each of the patients. The IOPs measured by rebound tonometer for the better and worse eyes in each position were compared using paired t tests. Agreement between the Goldmann applanation tonometry and rebound tonometry results was assessed by a Bland-Altman plot. The IOPs of the better and worse eyes in the sitting position showed no significant difference (P<0.476). The IOP of the worse eye was significantly higher than that of the better eye in the supine position (16.8 ± 3.0 mmHg vs. 15.1 ± 1.8 mmHg; P<0.001). The IOPs of the worse and better eyes in their dependent LDP were 19.1 ± 3.0 mmHg and 17.6 ± 2.3 mmHg, respectively (change in IOP, 1.6 ± 2.4 mmHg; P<0.001). Of the enrolled patients, 75.5% preferred the LDP, and 75.7% of these LDP-preferring patients preferred the worse eye dependent-LDP. The Bland-Altman plot comparing the Goldmann applanation tonometry and rebound tonometry readings showed reasonable agreement between the 2 methods (r(2)<0.001; P = 0.972). This study showed that IOP-elevation asymmetry in LDP is associated with asymmetric visual field loss in glaucoma patients. The LDP, habitually preferred by glaucoma patients, also may be associated with asymmetric visual field damage.