Efficacy and Safety of Ab-Interno Canaloplasty in Post-Keratoplasty Patients: 3-Year Results

Purpose: To evaluate the effectiveness and safety of ab-interno canaloplasty (ABiC) for managing intraocular pressure (IOP) in patients following keratoplasty over a three-year period. Methods: This retrospective analysis focused on post-keratoplasty patients treated with ABiC with the iTrack microcatheter (Nova Eye Medical, Fremont, CA, USA) at a single institution. The study assessed the procedure's impact on IOP control, graft survival, and reliance on topical hypotensive medications, with additional observation for any postoperative complications. Surgical success criteria included the percentage of eyes with IOP <= 15 mmHg, IOP <= 18 mmHg, >= 20% IOP reduction, medication-free eyes, and eyes with concurrent IOP and medication reductions. Results: ABiC was performed successfully in a cohort of 16 post-keratoplasty (7 penetrating keratoplasty and 9 endothelial keratoplasty (EK)) eyes. Preoperative mean IOP of 25.8 +/- 7.2 mmHg was significantly reduced to 13.4 +/- 2.9 mmHg (p<0.001) at 1 year postoperatively and maintained at 13.1 +/- 3.9 mmHg (p=0.009) at 3 years postoperatively. The mean number of glaucoma medications was 3.5 +/- 1.7 at baseline, 2.8 +/- 1.3 at 1 year (p=0.107), and 2.5 +/- 1.2 at 3 years postoperatively (p=0.088). Eight eyes (66.7%) maintained IOP <= 15 mmHg, and 10 eyes (83.3%) maintained >= 20% IOP reduction at 3 years. The mean IOP and medication reductions from baseline at 3 years were -49.2% and -28.6%, respectively. Graft clarity was preserved in all patients except for one case of late graft failure that necessitated a repeat EK procedure. Post-ABiC complications included transient hyphema in two patients, neither of which led to long-term adverse outcomes. Conclusion: ABiC appears to be an effective and safe surgical intervention for sustained IOP reduction in post-keratoplasty patients. Graft survival trends are encouraging, and there was a low incidence of complications over a three-year follow-up period.