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

Abstract

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° incision group (n=34), the upper-180° incision group (n=34) and the lower-180° 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° group than in the lower-180° 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° incision, the upper-180° incision and the lower-180° incision, do not affect both the IOP reduction and the medications throughout 12 months of follow-up.

Trial registration number: UMIN000021169.

Keywords: Clinical Trial; Glaucoma; Intraocular pressure; Treatment Surgery.

Figure 1

Kaplan-Meier survival curves for patients treated with suture trabeculotomy ab interno with different extents and locations of Schlemm’s canal incision. Patients were randomly assigned to one of three groups: 360° Schlemm’s canal incision (360° group), upper-180° Schlemm’s canal incision (upper-180° group), or lower-180° Schlemm’s canal incision (lower-180° group). Surgical success (with or without medication use) was defined as an IOP value between 6 mmHg and 21 mmHg with a postoperative IOP reduction of at least 20% (criterion A) or an IOP value between 6 mmHg and 15 mmHg with a postoperative IOP reduction of at least 20% (criterion B). A surgical failure was defined as not meeting a success criterion at two consecutive follow-up visits at least 1 month after surgery or the need for additional glaucoma surgery. No significant difference was seen among these three groups for criterion A and criterion B.