Relationship between Schlemm’s canal incision length and the results of ab interno gonioscopy-assisted transluminal suture trabeculotomy

We retrospectively investigated the relationship between Schlemm's canal incision length and the results of ab interno gonioscopy-assisted transluminal suture trabeculotomy (GATST) with/without cataract surgery in open-angle glaucoma patients at Tsukazaki Hospital from 2018-2021. The study included 113 eyes from 76 patients (age: 70.0 ± 10.8 years; female/male: 43 [56.6%]/33 [43.4%]). GATST with and without cataract surgery was performed on 87 (phakia) [77.0%] and 26 eyes (pseudophakia) [23.0%], respectively; 102 [90.3%] eyes had primary open-angle glaucoma, and 11 [9.7%] had pseudoexfoliation glaucoma. Intraocular pressure (IOP) significantly decreased at 3/6/12 months, and the antiglaucoma eyedrop number significantly decreased at 6/12 months (all P values < 0.001). Linear mixed-effects models showed that incision length had significant positive associations with IOP spikes, hyphema grade, and IOP changes (amount/percentage) at 6 months; surgical success rate (IOP ≤ 15 mmHg, ≥ 20% reduction, no additional surgeries [criterion B]) at 6/12 months; and surgical success rate (IOP ≤ 21 mmHg, ≥ 20% reduction, no additional surgeries [criterion A]) at 12 months (Ps < 0.05). There were no significant associations with IOP changes at 12 months, surgical success rate (criterion A) at 6 months, or antiglaucoma eyedrop number at either timepoint (Ps > 0.05). Longer incisions were more likely to produce greater IOP reduction, requiring more attention to IOP spikes/hyphema.