Outcomes of a randomised trial comparing 360° and 180° schlemm's canal incisions in suture trabeculotomy ab interno for primary open-angle glaucoma and exfoliation glaucoma: a 5-year analysis.

Purpose: We aimed to report the 5-year efficacy and safety data of suture trabeculotomy ab interno (SLOT ab interno) in patients with primary open-angle glaucoma and exfoliation glaucoma.

Study design: Single-centre, three-arm randomised trial.

Methods: Ninety-nine eyes of 99 patients were randomly assigned to one of three groups: the 360° (n = 34), upper-180° (n = 34), and lower-180° (n = 31) groups. We evaluated intraocular pressure (IOP), medication use, and visual field progression. Surgical success (with or without medication) was defined as IOP ≤21 mmHg with a ≥20% reduction (criterion A) or IOP ≤15 mmHg with a ≥ 20% reduction (criterion B). Visual field progression was assessed by MD values at fixed postoperative time points and by the MD slope (dB/year).

Results: Fifty-six of 99 eyes (56.5%) completed 5 years of follow-up. At 5 years, the mean IOP decreased from 18.8 ± 5.7 to 13.5 ± 3.1 mmHg (28% reduction, p<0.001), with medication use decreasing from 3.3 ± 1.1 to 2.0 ± 1.7 (p=0.005) and a mean MD slope of -0.2 dB/year. No significant differences in surgical success rates (criteria A and B), MD values, or MD slopes were observed among the groups.

Conclusion: The extent of Schlemm's canal incisions (360°, upper-180°, or lower-180°) during SLOT ab interno has no significant effect on IOP reduction or medication use over 5 years.