Abstract:  Objective To explore the causes and clinical features of shallow anterior chamber after phacoemulsification combined with intraocular lens (IOL) implantation and gonio-surgery in primary angle-closure glaucoma (PACG) patients. Design Retrospective case series. Participants A consecutive series of 329 PACG patients (376 eyes) who underwent phacoemulsification combined with IOL implantation and gonioto-surgery at the Glaucoma Department of Beijing Tongren Hospital from July 1, 2023, to December 31, 2024, were included.  Methods The clinical data of the patients were reviewed. Using univariate Logistic regression analysis to evaluate the risk (OR value) of predicting the occurrence of shallow anterior chamber after surgery based on various parameters. Main Outcome Measures The clinical features, biometric parameters, OR value. Results  Among the 329 patients (376 eyes), 14 patients (17 eyes) developed early postoperative shallow anterior chamber. The age range of the shallow anterior chamber group was wide, from 39 to 83 years old. Preoperative uncorrected visual acuity, maximum intraocular pressure and visual field defect severity showed no statistically significant differences between two groups (P>0.05). Compared with the other PACG patients, the shallow anterior chamber group had a shorter axial length [(21.49±1.19) mm vs (22.40±0.71) mm, P=0.000], a shorter white-to-white distance [(11.19±0.31) mm vs (11.42±0.36) mm, P=0.005], a thinner lens thickness [(4.78±0.48) mm vs (5.02±0.32) mm, P=0.012], and a more anteriorly positioned scleral spur [(2.70±0.41) mm vs (2.88±0.17) mm, P=0.010], with statistically significant differences. For every 1.0 mm decrease in axial length, every 0.1 mm decrease in white-to-white distance, and every 0.1 mm decrease in scleral spur depth, the risk of postoperative shallow anterior chamber increased by 2.50 times (OR=0.423, 95%CI: 0.236-0.757), 5.78 times (OR=0.173, 95%CI: 0.038-0.797) and 9.26 times (OR=0.108, 95%CI: 0.012-0.951), respectively. Conclusions  The incidence of shallow anterior chamber after phacoemulsification combined with goniosurgery in patients with PACG is relatively low, which is mainly attributed to elevated vitreous cavity pressure arising from the pathophysiological mechanisms of atypical malignant glaucoma. Risk factors for this complication include short axial length, short white-to-white distance, and anteriorly positioned scleral spur. Among these, an anteriorly located scleral spur depth serves as the most sensitive predictive marker for postoperative shallow anterior chamber.

Key words: Primary angle-closure glaucoma, Gonio-surgery, Shallow anterior chamber, Scleral spur position