Conventional Trabeculotomy versus Gonioscopy-Assisted Transluminal Trabeculotomy: A Retrospective Cohort Study

Background: Conventional trabeculotomy (CT) is performed in an ab-externo manner with at most 120 degrees of incision area of Schlemm's canal (SC). Recently, gonioscopy-assisted transluminal trabeculotomy (GATT), which makes possible a 360-degree incision area of SC in an ab-interno manner, is introduced. The purpose of this study was to compare surgical outcomes for CT and GATT with and without simultaneous phacoemulsification over 24 months and to identify factors associated with surgical success. Results: Patients' baseline characteristics were not significantly different between two groups. The surgical success rate in CT and GATT with phacoemulsification groups were 40.4% and 96.6% and were significantly higher in the GATT group than in the CT group (p < 0.001). However, the surgical success rate in CT and GATT without phacoemulsification groups were 40.8% and 54.2%, and there were no significant differences between two groups without phacoemulsification (p = 0.55). Similarly, the postoperative IOP was significantly lower in the GATT group than in the CT group only in eyes with simultaneous phacoemulsification. There were no significant differences in the numbers of glaucoma medications between the two groups. Additional glaucoma surgery was needed in 13.2% and 25.9% of patients in the GATT and CT groups, respectively (p = 0.157). The multivariate logistic regression analysis revealed that the surgical success of trabeculotomy was significantly associated with combined phacoemulsification and the type of glaucoma surgery (GATT). Conclusion: Although both groups without phacoemulsification had a similar surgical success and IOP-lowering effect, GATT combined with phacoemulsification had a higher surgical success rate and a greater IOP-lowering effect compared with combined CT and phacoemulsification. Multivariate logistic regression analysis showed that the factors associated with higher surgical success at one year and two years postoperatively were the combined phacoemulsification procedure and the GATT.