Abstract: Objective To observe the efficacy and safety of ab interno canaloplasty for primary open-angle glaucoma. Design Retrospective case series. Participants 30 eyes (30 cases) of primary open-angle glaucoma during October 2018 to March 2019 in Qingdao Eye Hospital. Methods All subjects underwent  ab interno canaloplasty, which was performed through a transparent cornea incision into the anterior chamber. Trabecular meshwork and the inner wall of Schlemm tube were horizontally cut with an incision about 1 mm. The tip of iTrack microcatheter was aligned with the incision and inserted into Schlemm tube for 360 expansion. Follow-up for 3 months after operation was conducted. The opening of Schlemm tube was examined with Heidelberg anterior segment OCT. Image J performed OCT image analysis to measure Schlemm tube width and length. Main Outcome Measures Intraocular pressure (IOP), amount of intraocular pressure lowering drugs used, opening degree of schlemm tube. Results Among the 30 patients, the success rate of 360 degree crossing was 83.33%. The preoperative mean IOP was (30.43±8.65) mmHg. The postoperative mean IOP at 1 day, 1 week, 1 month and 3 months were (14.33±3.88) mmHg, (18.21±7.52) mmHg, (16.55±4.92) mmHg and (16.61±3.99) mmHg. The IOP at each time point after operation was significantly lower than that before operation (P<0.001). The average number of IOP-lowering drugs used before surgery was (2.73±0.91), and the number of IOP-lowering drugs used after surgery was (0.84±1.25), (0.75±0.91) and (0.92±0.95) at 1week, 1 and 3 months  (P<0.001). The mean transverse diameter and longitudinal diameter of Schlemm tube were respectively (255.22±59.67) μm and (37.89±12.00) μm  before operation and (306.11 59.44) μm and (64.22 34.62) μm  after operation (P=0.02, 0.04). The success rates of 1 week, 1 month and 3 months after operation were 69.23%, 85.00% and 84.61%. The most common postoperative complication was hyphema (46.67%), and the incidence of hemorrhagic posterior elastic membrane separation was 3.33%.  Conclusion Ab interno canaloplasty is a safe and effective minimally invasive surgery for primary open angle glaucoma with good short-term effect and low complication. （Ophthalmol CHN, 2020,29: 20-25）

Key words: primary open angle glaucoma, ab interno canaloplasty