Canaloplasty: Circumferential viscodilation and tensioning of Schlemm's canal using a flexible microcatheter for the treatment of open-angle glaucoma in adults

PURPOSE: To evaluate the safety and efficacy of circumferential viscodilation and tensioning of the inner wall of Schlemm's canal in a new surgical procedure for the treatment of open-angle glaucoma (OAG). SETTING: Fourteen clinical sites in the United States and Germany. METHODS: In this international multicenter prospective study of adult patients with OAG having glaucoma surgery, patients with qualifying preoperative intraocular pressure (IOP) of at least 16 mm Hg or higher and open angles were eligible. Evaluation was performed at baseline and 1 day, 1 week, and 1, 3, 6, and 12 months preoperatively. After a nonpenetrating dissection technique to expose Schlemm's canal was performed, a flexible microcatheter (iTrack 250A, iScience Interventional) was used to dilate the full circumference of the canal by injecting sodium hyaluronate 1.4% (Healon GV) during catheterization. A suture loop was placed in the canal to apply tension to the trabecular meshwork. High-resolution ultrasound imaging was used to assess Schlemm's canal and anterior segment angle morphology, including distension of the trabecular meshwork caused by the tensioning suture. Data analysis was performed in 2 groups: Group 1, in which patients met all inclusion criteria, and Group 2, made up of Group 1 patients who had successful suture placement. RESULTS: Group 1 comprised 94 patients and Group 2, 74 patients. The mean baseline IOP in Group 1 was 24.7 mm Hg+/-4.8 (SD) on a mean of 1.9+/-1.0 medications per patient. In Group 2 (patients with sutures), the mean IOP was 16.1+/-4.7 mm Hg 3 months postoperatively, 15.6+/-4.0 mm Hg at 6 months, and 15.3+/-3.8 mm Hg at 1 year. Medication use dropped to a mean of 0.6+/-0.9 per patient at 12 months. Suture tensioning was an apparent contributing factor in achieving surgical success. Patients with measurable trabecular meshwork distension from suture tension had a mean IOP of 15.9+/-5.2 mm Hg at 6 months and 14.5+/-3.0 mm Hg at 12 months. Surgical and postsurgical adverse events were reported in 15 of 94 patients (16%) and included hyphema (3), elevated IOP greater than 30 mm Hg (3), Descemet's tear (1), hypotony (1), choroidal effusion (1), and exposed closure suture with eyelid edema and erythema epiphora (1); 4 patients were subsequently converted to trabeculectomy. CONCLUSION: Circumferential viscodilation and tensioning of Schlemm's canal was a safe and effective surgical procedure to reduce IOP in adult patients with OAG.