·AIM: To explore whether the drainage angle could be reopened by surgery in patients with severe acute angle-closure glaucoma at " the greatest degree " of angle closure, and to study the treatment methods, such as double-paracentesis, phacoemulsification combined with goniosychialysis, and the effectiveness. ·METHODS: Retrospective observational case series. From November 2008, to November 2015, there were 33 patients with severe acute angle-closure glaucoma and 360° angle closure. Drug treatment showed no effect on them, so initial double-paracentesis ( anterior chamber paracentesis combined with vitreous paracentesis ) was applied. Then, either phacoemulsification combined with goniosychialysis or trabeculectomy surgery was performed after 7-14d, which was chosen based on the result of gonioscope during the surgery. The intraocular pressure, angle changes, and complications were observed. The follow-up period was 6mo to 3a. ·RESULTS: Of 33 participants enrolled, 32 had normal intraocular pressure after " double-paracentesis" ( 2 had normal intraocular pressure after laser peripheral iridotomy ). The mean intraocular pressure was significantly reduced from 53. 4 ± 10. 7mmHg to 16. 9 ± 13. 2mmHg ( t= 9. 21, P<0. 001 ) by applying " double-paracentesis", and 1 still had higher intraocular pressure. The mean intraocular pressure ( 16. 7 ± 4. 8mmHg ) was 0. 2mmHg lower after phacoemulsification than after" double- paracentesis " while there was no significant difference (t=0. 38,P>0. 05). One patient had abnormal intraocular pressure until 30d after phacoemulsification. Every participant had 360° angle closed before " double-paracentesis", 32 patients had opened angle ( mean 131. 8°± 111. 3°) after " double-paracentesis " and mean (228. 6°± 108. 3°) during phacoemulsification, and mean (234. 6°± 107. 2°) at 3mo after phacoemulsification. There was a significant difference between the post -paracentesis and intraoperative values ( t = 4. 52, P <0. 001 ). There was no difference between the intraoperative and postoperative values ( t = 0. 46, P>0. 05). No patients had serious adverse events. · CONCLUSION: For the " maximum degree " angle closure of severe acute angle-closure glaucoma, "double-paracentesis" combined with phacoemulsification can be chosen to open the angle gradually, and reduce intraocular pressure in vast majority of patients.