Comparison of Anterior Chamber Depth with Posture Change Between Primary and lens-induced Angle Closure Glaucomas

Purpose: To compare the changes in central anterior chamber depth between supine and sitting positions using an ultrasound biomicroscope among acute angle closure glaucoma, lens-induced angle closure glaucoma, and normal groups. Methods: This study included 18, 13, and 29 individuals with acute angle closure glaucoma, lens-induced angle closure glaucoma, and control, respectively. The central anterior chamber depth, trabecular iris angle, corneal curvature, and axial length were measured in the sitting and supine positions. Results: The central anterior chamber depth in the supine and sitting positions were 1.61 +/- 0.47 mm and 1.55 +/- 0.46 mm in the acute angle closure glaucoma, which were significantly smaller than those in the normal group (2.48 +/- 0.49 mm and 2.47 +/- 0.50 mm) (p = 0.01 and p = 0.009, respectively). In lens-induced angle closure glaucoma, the central anterior chamber depth in the supine and sitting positions were 1.65 +/- 0.84 mm and 1.52 +/- 0.82 mm, respectively, which were significantly smaller than those in the normal group (p < 0.001 for both). The absolute change in central anterior chamber depth with posture alteration was significantly larger in both acute angle closure glaucoma (0.15 +/- 0.09 mm) and lens-induced angle closure glaucoma (0.25 +/- 0.11 mm) than in the normal control (0.09 +/- 0.08 mm) (p = 0.011, p < 0.001, respectively). The largest amount of change was shown in the lens-induced angle closure glaucoma (p = 0.012). The absolute change in anterior chamber angle with posture change wa not significantly different between the groups (p = 0.165). Conclusions: Compared to the control group, the central anterior chamber depth was smaller in both glaucoma groups. The absolute change in the anterior chamber depth with posture was significantly larger in the lens-induced angle closure glaucoma than in acute angle closure glaucoma.