Comparison of Efficacy between 120° and 180° Schlemm's Canal Incision Microhook Ab Interno Trabeculotomy

We compared surgical outcomes in patients with either primary open-angle glaucoma or exfoliation glaucoma after undergoing combined phacoemulsification with either a 120 degrees or 180 degrees incision during a Schlemm's canal microhook ab interno trabeculotomy (mu LOT-Phaco). This retrospective comparative case series examined 52 mu LOT-Phaco eyes that underwent surgery between September 2017 and December 2020. Surgical qualified success was defined as an intraocular pressure (IOP) of <= 20 mmHg, >= 20% IOP reduction with IOP-lowering medications, and no additional glaucoma surgery. Success rates were evaluated by Kaplan-Meier survival analysis. The number of postoperative IOP-lowering medications and occurrence of complications were also assessed. Mean preoperative IOP in the 120 degrees group was 16.9 +/- 7.6 mmHg, which significantly decreased to 10.9 +/- 2.7 mmHg (p < 0.01) and 11.1 +/- 3.1 mmHg (p = 0.01) at 12 and 24 months, respectively. The mean number of preoperative IOP-lowering medications significantly decreased from 2.8 +/- 1.4 to 1.4 +/- 1.4 (p < 0.01) at 24 months. Mean preoperative IOP in the 180 degrees group was 17.1 +/- 7.0 mmHg, which significantly decreased to 12.1 +/- 3.2 mmHg (p = 0.02) and 12.9 +/- 1.4 mmHg (p = 0.01) at 12 and 24 months, respectively. The mean number of preoperative IOP-lowering medications significantly decreased from 2.9 +/- 1.2 to 1.4 +/- 1.5 (p < 0.01) at 24 months. The probability of qualified success at 24 months in the 120 degrees and 180 degrees groups was 50.4% and 54.6%, respectively (p = 0.58). There was no difference observed for hyphema formation or IOP spikes. Surgical outcomes were not significantly different between the 120 degrees and 180 degrees incisions in Schlemm's canal.