Association Between Cilio-Lenticular Distance and Anterior Chamber Depth in Primary Angle-Closure Glaucoma

Purpose: To investigate the lens and ciliary spatial characteristics in primary angle-closure glaucoma (PACG) patients using ocular magnetic resonance imaging (MRI), aiming to elucidate the mechanism underlying PACG pathogenesis. Methods: This is a cross-sectional observational case-control study that used a clinical 3.0T MRI with a specialized coil to acquire binocular images in the axial plane. Quantitative measurements were conducted to obtain anatomical parameters of the lens, ciliary body, and vitreous cavity, including lens equator diameter (LED), cilio-lenticular distance (CLD), ciliary to ciliary distance (CCD), vitreous cavity width, and vitreous cavity depth. Linear mixed effects models were used for statistical analysis. Result: Twenty-five eyes of 13 PACG patients and 19 eyes of 10 healthy participants were enrolled in this study. The PACG group exhibited a statistically significant larger Sectional Area of Lens (33.72 ± 2.50 mm2 vs. 30.72 ± 2.42 mm2, P = 0.005), lower CCD (9.74 ± 0.45 mm vs. 10.41 ± 0.62 mm, P = 0.003), and lower CLD (0.51 ± 0.09 mm vs. 0.85 ± 0.17 mm, P < 0.001). No differences were found in LED and characteristic parameters of vitreous cavities. CLD demonstrated a high predictive performance for PACG (area under the curve [AUC] = 0.979), approaching that of the classical parameter anterior chamber depth (AUC = 0.993), with both showing statistical significance (P < 0.001). Conclusions: A smaller CLD correlates with a shallow anterior chamber and indicates a more crowded ciliary-lens configuration, a crucial indictor of PACG.