Effect of Body Posture on Anterior Chamber Angle in Healthy Subjects: an Anterior Segment Optical Coherence Tomography Study

Abstract

Purpose : Previous studies have reported the effect of changing body posture from the sitting to supine position on intraocular pressure and anterior chamber angle (ACA) parameters. However, the effect of lateral decubitus (LD) positioning on ACA parameters is unknown. This study evaluated how the postural alteration from sitting to LD position affects the anterior chamber angle in healthy subjects.

Methods : Twenty-three healthy subjects participated in this study. They underwent anterior segment optical coherence tomography (AS OCT) imaging in the sitting position. Then, they were asked to change their body posture to the left LD position. Ten minutes after assuming the left LD position, they underwent AS OCT imaging in the same body posture. ACA parameters [1) trabecular-iris angle (TIA); 2) angle opening distance at 500 μm from the scleral spur (AOD₅₀₀), 3) trabecular-iris space area 500 (TISA₅₀₀), 4) anterior chamber depth (ACD)] obtained in each posture were compared between the sitting position and the LD position.

Results : When the participants changed the body posture from the sitting to the left LD position, ACA parameters of right eyes showed significant decreases on the temporal side (TIA: 39.53 ± 2.38^ο to 38.31 ± 3.47^ο; AOD₅₀₀: 0.72 ± 0.13 to 0.65 ± 0.08; TISA₅₀₀: 0.25 ± 0.06 to 0.22 ± 0.04; all p<0.05), whereas they showed no significant changes on the nasal side. Compared between the sitting and left LD postures, ACA parameters of left eyes showed significant decreases only on the nasal side (TIA: 39.49 ± 2.24^ο to 38.17 ± 2.76^ο; AOD₅₀₀: 0.68 ± 0.09 to 0.64 ± 0.10; TISA₅₀₀: 0.23 ± 0.04 to 0.21 ± 0.03; all p<0.05). ACD measured in the sitting position did not differ from that measured in the left LD posture.

Conclusions : Compared with that measured in the sitting position, ACD of healthy subjects did not show any significant change in the left LD position. However, ACA parameters decreased when the site of measurement was changed from the nasal or temporal side in the sitting posture to the upper side of the eyeball in the LD posture, whereas such change was not found when the site of measurement was changed from the nasal or temporal to the lower side of the eyeball in the LD posture.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.