Effect of lateral decubitus position on intraocular pressure in glaucoma patients with asymmetric visual field loss

Purpose: To investigate the effect of the lateral decubitus position (LDP) on intraocular pressure (IOP) in glaucoma patients with asymmetric visual field loss.

Design: Prospective, cross-sectional study.

Participants: 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.

Methods: 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.

Main outcome measures: 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.

Results: 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).

Conclusions: 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.