Comparison of Phacoemulsification with and without Trabecular Micro-Bypass Stent in Primary Open-Angle Glaucoma and Normal Tension Glaucoma Population, 18 Months Outcome

Purpose: To evaluate the efficacy of first-generation iStent combined with phacoemulsification (phaco-iStent) versus phacoemulsification alone in Taiwanese patients with primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG). Methods This retrospective case-control study included POAG or NTG patients who underwent phaco-iStent or phacoemulsification alone between January 2018 and December 2020. The primary outcome measures included changes in estimated washout IOP (ewIOP), unwashed intraocular pressure (uwIOP), and the number of antiglaucoma medications. Additional efficacy evaluations included the proportion of eyes with surgical success. This study also conducted subgroup analysis for POAG and NTG. Results A total of 24 eyes in the iStent group (POAG: 16; NTG: 8) and 47 eyes in the control group (POAG: 29; NTG: 19) were enrolled. The iStent group showed a more significant decrease in ewIOP compared to the control group throughout the 18-month follow-up, with significant differences at 1, 3, 6, 12, and 18 months (-15.06~-21.92% vs. +1.66~-4.73%, P value = 0.005 ~ 0.045). After adjusting for confounding factors, the generalized estimating equation for ewIOP remained significant (β= -16.083, P value < 0.001). At 18 months, the iStent group had higher qualified and complete success rates than the control group (73.3% vs. 16.7%, P value = 0.001 and 53.3% vs. 0%, P  = 0.002, respectively), and the NTG-iStent subgroup showed the highest complete success rate (85.7% at 18 months). Conclusions Phaco-iStent is an effective treatment option for Taiwanese patients with POAG and NTG. It offers significant IOP reduction and higher success rates, especially in NTG eyes.