Objective: To investigate the role the lens dimensions played on the pathogenesis of primary angle-closure glaucoma.Methods: 38 eyes of 20 patients with primary angle-closure glaucoma ( PACG) and 35 eyes of 22 normal individuals withoutocular abnormalities were examined. The anatomical parameters of the lens and other structures of the anterior segment werecalculated using B ultrasound, computer image processing and ultrasound biomicroscopy ( UBM) . The parameters were com-pared between the patients and normal subjects. Correlation analysis was used to determine the relationship between the radii ofcurvature of the anterior lens surface ( RCALS) and the other parameters of the anterior segment. Results: Compared with thenormal eyes, the eyes of PACG had thicker lens, steeper curvature of anterior lens surface, decreased depth of the anteriorchamber, narrower chamber angle, and more anterior position of the ciliary bodies and lens. All these differences were signif-icant( P < 0.05 or P < 0.01) . In the PACG group, the RCALS had significantly negative correlation with the central and pe-ripheral lens thickness ( P < 0.01 and P < 0.05 respectively) , and had positive correlation with relative lens position, anteriorchamber depth( ACD) , angle-open distance at 500 um( AOD500) , trabecular iris angle( TIA) and trabecular ciliary processesdistance( TCPD, P < 0.05 or P < 0.01) . Conclusion: The occurrence of PACG is relevant to the abnormal anatomical struc-tures of the anterior segment. Among all factors, the lens parameters play an important role in the pathogenesis. Increased lensthickness, relative more anterior position of lens, especially steepened curvature of anterior lens surface are predisposing factorsof the pathologic phenomenon in PACG including pupillary blockage, shallow anterior chamber, secondary closure of chamberangle and elevation of intraocular pressure. Objective: To investigate the role of the lens size played on the pathogenesis of primary angle-closure glaucoma. Methods: 38 eyes of 20 patients with primary angle-closure glaucoma (PACG) and 35 eyes of 22 normal individuals withoutocular abnormalities were examined. The anatomical parameters of the lens and other structures of the anterior segment werecalculated using B ultrasound, computer image processing and ultrasound biomicroscopy (UBM). The parameters were com-pared between the patients and normal subjects. Correlation analysis was used to determine the relationship between the radii of curvature of the anterior lens surface (RCALS) and the other parameters of the anterior segment. Results: Compared with normal eyes, the eyes of PACG had thicker lens, steeper curvature of anterior lens surface, decreased depth of the anterior chamber, narrower chamber angle, and more anterior position of the ciliary bodies and lens. All these differences were signif-icant (P <0.05 or P <0.01). In the PACG group, the RCALS had significantly negative correlation with the central and pe-ripheral lens thickness (P <0.01 and P <0.05 respectively), and had positive correlation with relative lens position, anterior chamber depth (ACD), angle-open distance at 500 um (AOD500), trabecular iris angle (TIA) and trabecular ciliary processes distance (TCPD, P <0.05 or P <0.01). Conclusion: The occurrence of PACG is relevant to the abnormal anatomy-tures of the anterior segment. Among all factors, the lens parameters play an important role in the pathogenesis. Increased lensthickness, relative more anterior position of the lens, especially steepened curvature of anterior lens surface are predisposing factors of the pathologic phenomenon in PACG including pupillary blockage, shallow anterior chamber , secondary closure of chamberangle and elevation of intraocular pressure.