Objective:To observe the clinical efficacy of ultrasound cycloplasty (UCP) in the treatment of uncontrolled intraocular pressure (IOP) after glaucoma surgery.Methods:An observational case series study was carried out.Twenty-eight consecutive patients (28 eyes) with uncontrolled IOP after glaucoma surgery who received UCP treatment in The First Affiliated Hospital of Zhengzhou University from July 2018 to October 2019 were enrolled.The IOP of these patients was ≥21 mmHg (1 mmHg=0.133 kPa) under the maximum tolerated dose.According to preoperative IOP and visual acuity, the patients were divided into 8-sector group (17 eyes) and 10-sector group (11 eyes). The duration of UCP operation, preoperative and postoperative 1-day, 1-week, 2-week, 1-month and 3-month IOP and BCVA, the types of drugs for lowering IOP preoperatively and postoperatively, preoperative and postoperative 3-month ocular pain grading and corneal endothelial cell counts, and adverse reactions during the operation and after surgery were recorded.This study adhered to the Declaration of Helsinki.The study protocol was approved by an Ethics Committee of The First Affiliated Hospital of Zhengzhou University (No.2020-KY-154). Written informed consent was obtained from each subject prior to any medical examination.Results:The duration of UCP operation was 3 to 7 minutes, with an average of (4.30±1.26) minutes.The IOP at 1 day, 1 week, 2 weeks, 1 month and 3 months after operation was (32.96±10.49), (25.89±7.25), (24.50±6.23), (24.07±6.59), (24.32±6.52)mmHg, respectively, which were significantly lower than (45.82±8.81) mmHg before operation (all at P<0.05). There was no significant difference in IOP between the 8-sector group and 10-sector group ( Fgroup=1.271, P=0.270), but there was a significant difference in IOP between the two groups before and after operation ( Ftime=54.388, P<0.01), and the postoperative IOP at various time points in the two groups were lower than the preoperative IOP, showing statistical significances (all at P<0.05). There was no significant difference in BCVA before and after surgery ( F=2.562, P=0.075). There was a statistically significant difference in BCVA between the 8-sector group and 10-sector group ( Fgroup=12.602, P=0.001), but no statistically significant difference was found in BCVA between the two groups before and after surgery ( Ftime=1.701, P=0.139), and the BCVA in the 8-sector group was better than the 10-sector group at various time points (all at P<0.05). The types of IOP lowering drugs used in the 8-sector group and 10-sector group were 3 (2, 3) and 3 (2, 4) before operation respectively, and 0 (0, 1) and 0 (0, 0) at 3 months after operation respectively.The preoperative ocular pain grade was 2 (2, 2), and the postoperative 3-month ocular pain grade was reduced to 1 (0, 1), and the difference was statistically significant ( Z=-4.824, P<0.05). The postoperative 3-month pain grading in the 8-sector and 10-sector groups were significantly lower than the preoperative pain grading ( Z=-3.739, -3.127; both at P<0.05). The corneal endothelial cell count was significantly decreased from (1 967.15±186.06) cells/mm 2 before operation to (1 861.08±206.63) cells/mm 2 at 3 months after operation ( t=2.781, P=0.017). No serious complications occured during the operation.Postoperative adverse reactions included chemosis and bulbar hyperemia, corneal edema, headache, ocular pain, anterior chamber inflammation, etc.Serious complications such as low IOP, macular edema, vision loss or eyeball atrophy were not observed. Conclusions:UCP has no surgical incision.Treatment of both 8 sectors and 10 sectors can effectively reduce IOP, reduce the types of IOP lowering drugs, and relieve ocular pain in patients with uncontrolled IOP after glaucoma surgery with few intraoperative and postoperative adverse reactions.