To compare clinical outcomes between trabeculotomy ab externo (TLO) and trabecular ablation ab interno using a Trabectome (TAT) for open angle glaucoma (OAG).

Prospective and retrospective cohort study.We prospectively recruited 100 patients who underwent TAT between May 2016 and May 2017, and retrospectively recruited 90 patients who underwent TLO between May 2013 and May 2016. We included OAG patients who could be followed up for more than 12 months after surgery. Surgical outcomes were compared between groups. Kaplan-Meier analyses and Cox proportional hazards' models were used for four sets of criteria using postoperative intraocular pressures (IOP) ≤ 18 or ≤ 17 mmHg, and/or showing ≥ 20% reduction from baseline.

Mean preoperative IOPs were 22.9 ± 7.6 mmHg in the TAT group and 22.2 ± 6.4 mmHg in the TLO group. Mean postoperative IOPs in the TAT group were 15.8 ± 3.6 mmHg at 12-months, and 15.3 ± 5.5 mmHg at 36-months, and 16.6 ± 3.7 mmHg at 12 months and 15.9 ± 3.2 mmHg at 36 months in the TLO group. Postoperatively, success rates at 36-months were significantly higher in the TLO group in some criteria; IOP reductions at 1- and 2- years were significantly higher in the TLO group; these differences were not significant after adjustment with other potential prognostic factors. The number of glaucoma medications were significantly higher in the TAT group, at 2-years (P < 0.001) but not at 3-years (P = 0.24).

Surgical successes following TLO and TAT are not significantly different 3 years postoperatively after adjustment of potential prognostic factors.