Long-term efficacy and safety of ab externo canaloplasty in the Polish Caucasian population with open-angle glaucoma: A 3-year retrospective study

This study aimed to assess the effectiveness and safety of ab externo canaloplasty over a 3-year follow-up period in Polish Caucasian patients with glaucoma. This retrospective study of a cases series was conducted at the Department of Ophthalmology Medical University of Bialystok, Poland. Primary outcome measures were intraocular pressure and medication burden. Secondary outcome measures were best corrected visual acuity, retinal nerve fiber layer thickness, visual field test results, endothelial cell density, intraoperative and postoperative complications, and additional glaucoma surgery. The study group consisted of 160 eyes diagnosed with early to-moderate primary open-angle glaucoma and treated with ab externo canaloplasty from 2014 to 2020. The criteria for qualified and complete success were intraocular pressure < 18 mmHg or ≥ 20% reduction in intraocular pressure from baseline with or without antiglaucoma medications, respectively. After surgery, the mean intraocular pressure decreased from 19.23 ± 4.33 to 14.52 ± 3.79 mmHg, which constituted a 36.7 ± 7.8% reduction compared to the baseline value. The number of medications decreased by two at the end of the study period (from 2.69 ± 1.05 to 0.32 ± 0.75). Complete and qualified success were achieved in 58.7% and 68.7% of the patients, respectively, at the end of follow-up. An incomplete cannulation of Schlemm's canal was the most common intraoperative complication, occurring in 32 eyes (20%). The most frequent postoperative complications were hyphema, Descemet's membrane detachment, and a transient increase in intraocular pressure. Additional surgical procedure was required in seven cases (4.4%). In 16 patients (10%), medical treatment was re-administered. Overall, our findings suggest that ab externo canaloplasty is a good option for Polish Caucasian patients with primary open-angle glaucoma. It reduces intraocular pressure and has a low postoperative complication rate. Additional glaucoma surgery or re-administration of medications is required if the target intraocular pressure is unsatisfactory.