Comparison of Surgical Outcomes Between Ab Interno Suture Trabeculotomy and Ab Externo Metal Trabeculotomy in Adult Patients with Glaucoma

Yasumasa Otori, Takanori Matsuoka, Miho Kumoi, Eri Tachibana, Chieko Tsujino, Satoshi Matsuda Department of Ophthalmology, National Hospital Organization, Osaka National Hospital, Osaka, JapanCorrespondence: Yasumasa Otori Email otori.yasumasa.fe@mail.hosp.go.jpPurpose: To compare the outcomes of ab interno suture trabeculotomy (AbI-TLO) and ab externo metal trabeculotomy (AbE-TLO) in adult patients with glaucoma aged over 40 years.Patients and Methods: A retrospective chart review was conducted, including adult patients with glaucoma who underwent AbI-TLO or AbE-TLO between January 2015 and June 2019. A single surgeon (YO) performed all the operations. Eighty-one patients (81 eyes) were included in this study. Surgical success was defined as a postoperative intraocular pressure (IOP) of ≤ 18 mmHg and an IOP reduction of ≥ 20% from the preoperative IOP, without requiring additional glaucoma surgery. Success rates were assessed using Kaplan–Meier survival curves and log-rank (Mantel–Cox) tests, while risk factors were analyzed using the Cox proportional hazards model.Results: Forty-nine patients who underwent AbI-TLO and 32 patients who underwent AbE-TLO were studied; the preoperative IOPs were 27.9 ± 7.3 (mean ± standard deviation) mmHg and 25.6 ± 8.1 mmHg in the AbI-TLO and AbE-TLO groups, respectively (p=0.217). The 12-month postoperative IOPs were 15.8 ± 4.0 mmHg and 16.3 ± 4.2 mmHg in the AbI-TLO and AbE-TLO groups, respectively (p=0.724). The surgical success rates at 12 months were 77.6% and 62.5% in the AbI-TLO and AbE-TLO groups, respectively (p=0.144). Postoperative hyphema with level formation and ocular hypertension over 30 mmHg were observed in 22.4% and 26.5% of patients in the AbI-TLO group and 18.8% and 12.5% of those in the AbE-TLO group, respectively. Stepwise multivariate Cox regression analysis showed that a longer axial length was a risk factor for surgical failure (hazard ratio: 2.030; p=0.042).Conclusion: AbI-TLO and AbE-TLO had similar surgical outcomes and postoperative complications. A longer axial length was associated with an insufficient IOP reduction.Keywords: axial length, gonio-assisted transluminal trabeculotomy, intraocular pressure, MIGS, outcomes, trabeculotomy