12-month randomised trial of 360° and 180° Schlemm's canal incisions in suture trabeculotomy ab interno for open-angle glaucoma

Background/Aims To perform a 12-month comparison between the different extents and locations of Schlemm's canal incisions during suture trabeculotomy ab interno for open-angle glaucoma (OAG). Methods This is a prospective, single-centre, three-arm randomised trial. A total of 99 eyes of 99 patients were randomly assigned to one of three groups: the 360 degrees incision group (n=34), the upper-180 degrees incision group (n=34) and the lower-180 degrees incision group (n=31). Intraocular pressure (IOP), number of medications and complications were evaluated until 12 months after surgery. Surgical success (with or without medication) was defined as IOP <= 21 mmHg and >= 20% IOP reduction (criterion A) or IOP <= 15 mmHg and >= 20% IOP reduction (criterion B). Results The mean IOP (+/- SD) in all eyes was reduced from 18.6 (5.9) mmHg with 3.1 (1.1) medications to 13.7 (3.4) mmHg (20.8% reduction; p<0.001) with 1.4 (1.3) medications (p<0.001) at postoperative 12-month. Each group produced comparable mean reductions in both IOP and the number of medications throughout 12 months of follow-up. Kaplan-Meier cumulative survival analyses showed no significance among these three groups for criterion A and criterion B. Postoperative hyphema with niveau formation occurred significantly more in the 360 degrees group than in the lower-180 degrees group (p=0.031). Conclusions The different extents and locations of Schlemm's canal incisions during suture trabeculotomy ab interno for OAG, including the 360 degrees incision, the upper-180 degrees incision and the lower-180 degrees incision, do not affect both the IOP reduction and the medications throughout 12 months of follow-up.