To report the 24-month efficacy and safety of ab externo penetrating canaloplasty compared with trabeculectomy in the treatment of primary angle-closure glaucoma (PACG).This is a prospective, randomized, controlled trial. Patients with PACG and inadequately controlled intraocular pressure (IOP) were recruited. Patients enrolled were randomized to either ab externo penetrating canaloplasty (PCP group) or trabeculectomy (TRAB group). The main outcome measures were intraocular pressure (IOP), number of glaucoma medications, success rate and ocular surface disease index (OSDI) questionnaire. Surgical success (definition 1) was defined as 6mm Hg ≤ IOP ≤ 21mm Hg with an IOP reduction of ≥20% without glaucoma medications (complete success) or regardless of glaucoma medications (qualified success).A total of 52 eyes (44 patients) were finally enrolled with 25 eyes in PCP group and 27 eyes in TRAB group. PCP group (85.0%) had a similar qualified success rate compared with TRAB group (83.3%) with definition 1 at 24 months in intention to treat (ITT) analysis (P=1.000). In per protocol (PP) analysis, the qualified success with definition 1 were 81.3% in PCP group and 83.3% in TRAB group (P = 0.972). But PCP group had a lower success rate in postoperative IOP ≤15mm Hg with an IOP reduction of ≥20% than in TRAB group, in ITT analysis with complete success (PCP 35.0% vs TRAB 65.2%, P = 0.048) and PP analysis with qualified success (PCP 31.3% vs. TRAB 69.6%, P = 0.025). The mean OSDI score was equal in PCP group (11.9 ± 8.5) and TRAB group (16.6 ± 14.3) (P = 0.302). Hypotony-associated complications were the main complications in PCP group and TRAB group (24.0% vs. 33.3%, P = 0.458).Compared with trabeculectomy, ab externo penetrating canaloplasty had a similar qualified success rate and comparable complications at 24 months. Without frequent bleb interventions, penetrating canaloplasty may be a promising surgery for PACG patients especially with early or mild stages.Copyright © 2025. Published by Elsevier Inc.