Comparison of surgical outcomes between canaloplasty and trabeculectomy with mitomycin C at 2-year follow-up: A longitudinal cohort study

PURPOSE: To compare operative outcomes of patients after canaloplasty and trabeculectomy with mitomycin C (MMC) through 2-year follow-up. METHODS: We included 31 eyes of 31 patients with primary open-angle glaucoma (POAG) who underwent canaloplasty and 37 eyes of 37 patients with POAG who underwent trabeculectomy with MMC with 24 months of postoperative follow-up. All surgeries were performed by a single surgeon between January 2005 and May 2011. Failure was defined as intraocular pressure (IOP >18 or <4 mmHg at 2 years), second operative procedure, or loss of light perception. Change in IOP, visual acuity (VA), glaucoma medications, and complication rates at 24 months were analyzed. RESULTS: Caucasians made up to half of the patients included in this study (58% vs. 43%) while the rest where either African Americans (32% vs. 43%) or Hispanic (10% vs. 14%) patients between the canaloplasty and trabeculectomy group. Both groups showed significant reduction in IOP from baseline at 24 months. Trabeculectomy patients had a greater mean reduction of IOP compared to canaloplasty patients (12.2 ± 12 vs. 4.7 ± 7.5, P = 0.003) and also achieved lower IOP at 24 months (12.2 ± 4.1 vs. 14.9 ± 6.0, P = 0.03). Postoperative glaucoma medication use was less in the trabeculectomy group (n = 0, interquartile range [IQR] 0–2) compared to those in whom canaloplasty was performed (n = 2, IQR 0–3, P = 0.02). VA showed no statistical change in either group over 2 years. Overall failure rates at 2 years were comparable between the two groups: 32% for trabeculectomy and 26% for canaloplasty (P = 0.6). Subgroup analysis revealed a lower failure rate in Caucasions (15%) when compared to Blacks (42%) and Hispanics/others (50%, P = 0.03). CONCLUSION: Canaloplasty and trabeculectomy both achieved significant reduction in IOP with comparable success rates. Trabeculectomy can achieve a greater reduction in IOP while requiring fewer medications however is associated with more intensive postoperative care and frequent interventions. Pigmented populations have worse outcomes compared to Caucasians.