One-Year Outcomes of Trabeculotomy with 120°, 180°, or 360° Schlemm's Canal Incision for Primary Open-Angle Glaucoma: A Retrospective Study.

Primary open-angle glaucoma (POAG), if caused by elevated intraocular pressure (IOP), may require a trabeculotomy (LOT), in which the trabecular meshwork (TM) and Schlemm's canal (ISC) are incised. However, the association between the incision angle and outcomes remains unclear. Therefore, in this study, we investigated the surgical outcomes of a trabeculotomy combined with cataract surgery in patients with POAG over a 12-month follow-up period. We included 66 patients (corresponding to 83 eyes) with POAG who underwent trabeculotomy ab externo with a metal probe (M-LOT: 120° incision of the TM and ISC), ab interno with a Kahook Dual Blade (K-LOT: 180° incision of the TM and ISC), or ab interno with a 5-0 nylon suture (S-LOT: 360° incision of the TM and ISC) between January 2015 and December 2022. We assessed IOP, the percentage reduction from preoperative IOP, the number of IOP-lowering medications taken, the incidence of postoperative complications, and the success rate using Kaplan-Meier survival analysis. The median IOP was significantly lower than the baseline across all three groups. The number of IOP-lowering medications taken was significantly reduced only in the M-LOT group. The mean percentage reduction from the preoperative IOP in the K-LOT group was significantly lower than that in the M and S-LOT groups. Beween those subjected to an ab ineterno LOT, the S-LOT group demonstrated a significantly higher rate of IOP reduction 12 months after the operation compared to the K-LOT group. Kaplan-Meier cumulative survival analyses revealed a lower success rate for the K-LOT group than for the M and S-LOT groups. The M-LOT group had the lowest incidence of hyphema and IOP spikes, whereas the S-LOT group had the highest incidence of these complications. The M-, K-, and S-LOTs had different surgical outcomes during the 12 months of follow-up, with the M-LOT group showing the fewest complications. These results will help in selecting the most suitable trabeculotomy strategy for patients with POAG. Based on the postoperative outcomes of the ab interno K- and S-LOTs, a wider incision of the TM and ISC leads to effective IOP reduction.