Comparison of Outcomes of Deep Sclerectomy, Canaloplasty, and Viscocanaloplasty: A Multi-Centred Study.

Prcis: Deep sclerectomy (DS) and canaloplasty provide better intraocular pressure (IOP) control than viscocanalostomy. DS required less glaucoma medications but more interventions to reach target IOP.

Purpose: To compare real-world outcomes of three non-penetrating glaucoma surgery (NPGS) techniques.

Methods: Retrospective, cohort study of consecutive patients undergoing canaloplasty (CP), deep sclerectomy (DS), and viscocanalostomy (VC), across nine European glaucoma units. Four intraocular pressure (IOP) criteria were used to define success at 2-year follow-up: (A)IOP≤21 mmHg and ≥20% reduction; (B)IOP≤18 mmHg and ≥20% reduction; (C)IOP≤15 mmHg and ≥25% reduction; (D)IOP≤12 mmHg and ≥30% reduction. Secondary outcomes included IOP control, BCVA, number of medications over time, risk factors for failure, complications, and post-operative interventions. Success was distinguished as qualified or complete, if reached with or without antiglaucoma medications, respectively.

Results: 600 eyes (545 patients) undergoing standalone CP (201 eyes), DS (200 eyes), and VC (199 eyes) were included. Qualified success rates of CP, DS, and VP at 24 months were, respectively: (Criterion A) 85.1%, 67.6% and 64.6%; (Criterion B) 85.1%, 66.1% and 58.6%; (Criterion C) 76.6%, 55.5% and 39.0%; (Criterion D) 27.7%, 28.5% and 22.1%. Success rates were significantly different across the three techniques (P=0.04 or below), except for complete success according to criterion A (P=0.07). Mean IOP(±SD) reduced from 25.2(±6.9), 20.5(±6.7), and 22.7(±7.2)mmHg pre-operatively to 13.1(±3.1), 12.9(±4.5), and 14.7(±4.6)mmHg at post-operative year 2 in the CP, DS, and VC groups respectively (P<0.001 between pre-operative and post-operative time points for all groups).

Conclusions: All three NPGS provide sustained IOP reduction, but DS and CP provide better success rates and IOP control. Success rates were low for the most stringent cut-offs, suggesting that other techniques such as trabeculectomy may be indicated when a very low target IOP is demanded.