Objective:To evaluate the efficacy and safety of phacoemulsification combined with gonioscopy-assisted angle plasty (Phaco-GAAP) for primary angle closure glaucoma (PACG) with cataract.Methods:A case series study was carried out.Twenty-five eyes of 22 patients with PACG and cataract were enrolled in Beijing Tongren Hospital from April 2022 to August 2022.All of the patients received Phaco-GAAP surgery.During the operation, viscoelastic-assisted goniosynechialysis was performed at first, followed by a secondary angle plasty for residual peripheral anterior synechiae (PAS) based on the quantified assessment by gonioscopy, and the extent of PAS was recorded intraoperatively.The operated eyes were followed at 1 day, 1 week, 1 month and 3 months after surgery to evaluate intraocular pressure (IOP), PAS range, the number of anti-glaucoma drugs application, operation-related complications, and success rate.The qualified success rate was defined as medicine-controlled IOP ≤21 mmHg after surgery, and complete success rate was defined as IOP ≤21 mmHg without any anti-glaucoma medication.This study complied with the Declaration of Helsinki and was approved by the Ethics Committee of Beijing Tongren Hospital (TRECKY2021-136). Written informed consent was obtained from each patient prior to entering the research cohort.Results:The extent of PAS was [270(225, 360)°], [165(110, 215)°] and [100(35, 175)°] at preoperation, first and secondary angle plasty, respectively, showing a significant difference among them ( χ2 =40.742, P<0.001). The PAS range was significantly reduced at first angle plasty in comparison with preoperation and was significantly reduced at secondary angle plasty in comparison with at first angle plasty (both at P<0.001), and the proportion of the angle PAS range ≥180° decreased from 48% to 24% after second angle plasty.In 13 eyes finished gonioscopy, the PAS range was [240(195, 305)°], [60(25, 182.5)°], [170(120, 275)°]and [180(140, 280)°]at preoperation, at the end of operation, postoperative 1 month and 3 months, respectively, with a significant difference ( χ2 =23.631, P<0.001). The PAS range was significantly smaller at postoperative 1 month, 3 months than that at preoperation (both at P=0.004) and larger than that at the end of operation ( P=0.011, P=0.003). The IOP was (40.19±17.23), (15.80±7.98), (13.89±5.09), (12.80±3.79) and(13.24±2.78) mmHg before operation and 1 day, 1 week, 1 month and 3 months after operation, respectively, showing a significant difference ( F=44.031, P<0.001), and the IOP was significantly reduced after operation (all at P<0.001). The PAS range at the end of operation was positively correlated with preoperation ( rs=0.409, P=0.042). The complete and qualified success rates were 95.8%, 95.8% for postoperative 1 month, 95.8% and 100% for postoperative 3 months, respectively.The primary complication was intraoperative anterior chamber angle hemorrhage, with an incidence of 68%. Conclusions:Phaco-GAAP can intraoperatively quantify PAS range and guide secondary angle plasty, therefore, it is an effective and safe surgical intervention for PACG with cataract.