One-year outcomes and predictable factors for microhook ab interno trabeculotomy

AIM: To investigate the one-year outcomes and factors that influence the results of microhook ab interno trabeculotomy (μLOT). METHODS: The medical records of consecutive patients with open angle glaucoma who underwent μLOT (including combination of μLOT and cataract surgery) between February 2018 and July 2019 were retrospectively reviewed. Surgical success was defined as the following: an intraocular pressure (IOP)≤21 mm Hg or IOP≤preoperative IOP with a reduced number of glaucoma eye drops, without additional glaucoma surgery, and assessed using Kaplan-Meier survival analysis. A multivariate Cox proportional-hazards regression model was used to investigate the factors associated with surgical failure. RESULTS: The 59 eyes of 59 patients comprising 28 eyes with primary open angle glaucoma (POAG) and 31 with secondary open angle glaucoma (SOAG) were included. The mean IOP and number of glaucoma eye drops significantly decreased from 25.3±7.2 mm Hg and 3.9±1.1, preoperatively to 16.1±4.4 mm Hg (P<0.01) and 2.1±1.8 (P<0.01), respectively, 12mo postoperatively, with a cumulative success rate of 63.1%. The one-year success rate was significantly higher in POAG eyes than in SOAG eyes (80.0% vs 48.0%; P=0.011, log-rank test). Multivariate analyses revealed SOAG [P=0.017, adjusted hazard ratio (aHR): 3.468, 95%CI: 1.246-9.654] and the postoperative IOP spike (IOP>25 mm Hg within 2wk post-surgery; P<0.001, aHR: 5.382, 95%CI: 2.113-13.707) as independent factors associated with surgical failure. CONCLUSION: The μLOT is a good treatment option for POAG eyes. However, the postoperative course should be carefully followed in cases with postoperative IOP spike.