This retrospective study adhered to the tenets of the Declaration of Helsinki and was approved by the institutional ethics committee, which waived the requirement for informed consent as the data analyzed were de-identified. Our study included patients with glaucoma who underwent µLOT before (Group 1) or after (Group 2) cataract surgery.
Most surgeries were performed by a single surgeon (Y.M.). Some surgeries were performed by three doctors supervised by Y.M. between April 2019 and June 2020 at Kochi University Hospital, Japan. We excluded patients with a postoperative follow-up of < 5 months. Data including age, sex, glaucoma type, IOP based on Goldmann applanation tonometry, number of antiglaucoma medications, best-corrected visual acuity (BCVA), surgical time, intraoperative and postoperative complications, and interventions for complications were collected from the medical charts.
First, peribulbar anesthesia was performed in all eyes using a sub-Tenon injection of 2% lidocaine. In Group 1, µLOT was performed using the following procedure: viscoelastic material (1% sodium hyaluronate, Opegan Hi, Santen Pharmaceutical, Osaka, Japan) was injected into the anterior chamber (AC) through two corneal ports on the temporal side created using a 20-gauge microvitreoretinal (MVR) knife (Mani, Utsunomiya, Japan). Using a Hill surgical gonioprism (Ocular Instruments, Bellevue, WA, USA) to observe the angle opposite the corneal port, a microhook was inserted into the AC through the corneal port. The tip of the microhook was then inserted into the Schlemm’s canal and moved circumferentially to incise the inner wall of the Schlemm’s canal and trabecular meshwork over 2 clock hours. Using the same procedure, LOT was performed using a microhook inserted through another corneal port. That is, a trabecular meshwork totaling 120 degrees or more was incised. In Group 1, standard phacoemulsification with IOL implantation was performed through an additional temporal corneal 2.8 mm incision. In Group 2, µLOT was performed using the same procedure as described above after standard phacoemulsification with IOL implantation.
Statistical analysis BCVA was converted to the logarithm of the minimum angle of resolution (logMAR) for statistical analysis. Wilcoxon signed-rank tests were used to compare IOP, number of antiglaucoma medications, and BCVA values preoperatively and 5–7 months postoperatively. Wilcoxon rank-sum tests were used to evaluate the group differences between continuous variables. The incidence of complications was compared between the groups using Fisher exact tests. Statistical significance was set at p < 0.05. All data were entered into an Excel spreadsheet (Microsoft Corp., Redmond, WA, USA) and analyzed using Excel 2016 with the add-in software Statcel 4.