Prospective 12-month outcomes of combined iStent inject implantation and phacoemulsification in Asian eyes with normal tension glaucoma

Abstract

Background Glaucoma is the leading cause of irreversible blindness. Normal tension glaucoma (NTG) is a subset of open-angle glaucoma, demonstrating glaucomatous optic nerve damage in the absence of raised intraocular pressure (IOP). NTG is more prevalent in Asian populations. While generally slow-progressing, NTG may be associated with significant central visual field loss. In recent years, minimally invasive glaucoma surgery has been added to the armamentarium of glaucoma surgery. This prospective study aims to evaluate 12-month surgical outcomes of combined iStent inject (Glaukos Corporation, Laguna Hills, CA) implantation and phacoemulsification in Asian eyes with NTG. Methods This is a prospective, single-centre case series of 30 eyes followed up until 12 months after surgery. Outcome measures included IOP, number of glaucoma medications, best-corrected visual acuity (BCVA) and intra and postoperative complications. Results Mean age of subjects was 73.1 ± 6.3 years. Majority were ethnic Chinese (n = 27, 90%). Baseline medicated mean IOP was 13.8 ± 2.4 mmHg and mean number of glaucoma medications was 1.3 ± 0.7. Mean Humphrey visual field mean deviation was − 13.7 ± 7.6. The mean IOP reduction at all timepoints from postoperative month (POM) 3 onwards was statistically significant (all P < 0.05), with mean reduction of 1.2 mmHg (95% CI: 0.1–2.2, P = 0.037) by POM12. There was statistically significant reduction in mean number of medications from postoperative day (POD) 1 onwards (all P < 0.05), with mean decrease of 1.0 medication (95% CI: 0.9–1.1, P < 0.001) by POM12. By POM12, 25 (83.3%) eyes were medication-free. Three (10%) eyes had stent occlusion by iris requiring laser iridoplasty. One eye had gross hyphema which resolved on conservative management before POM1. Mean BCVA improved from the baseline 0.3 ± 0.3 logMAR to 0.1 ± 0.1 logMAR postoperatively (P < 0.001). There were no major adverse or sight-threatening events. No eyes required further glaucoma surgery during the 12-month follow-up period. Conclusion Asian eyes with NTG which underwent combined iStent inject implantation and phacoemulsification demonstrated a significant and sustained reduction in IOP and glaucoma medications, up to 12 months postoperatively.

Long-term efficacy and safety of XEN-45 gel stent implantation in patients with normal-tension glaucoma

“…However, a study by Neuhann et al only reported a significant IOP reduction for this combined procedure after one year, but not after two years [ 19 ]. Similarly, a prospective study on this combined operation in NTG patients found only a moderate IOP reduction of 9% after one year [ 20 ]. These result appear to be in accordance with another report on combined phacoemulsification and a variety of MIGS (not including XEN-45) resulting in an 11% IOP reduction, with only 5.4% of NTG patients achieving sustained surgical success (defined as an IOP reduction ≥ 30%) after 1.5 years [ 21 ].…”

Premium Intraocular Lenses in Glaucoma—A Systematic Review

“…The later iteration of the iStent, the iStent Inject (Glaukos Corp., San Clemente, CA, USA), achieved US FDA approval in 2018. Ang et al [ 146 ] demonstrated minimal influence of iStent inject implantation on the MAE (−0.13 ± 0.08 D), with 82.8% of eyes achieving a post-operative refraction within 0.5 D of target in combined iStent inject implantation and phacoemulsification in Asian eyes with NTG. Ioannidis et al [ 147 ] concluded too that the iStent inject device is refractively neutral—73.9% and 98.9% of eyes were within 0.5 D and 1.0 D of the target refraction, respectively.…”

Spotlight on Schlemm’s Canal MicroStent Injection in Patients with Glaucoma

“… 17 , 18 Ang et al additionally conducted a prospective study of 30 Asian eyes with NTG and reported significant reductions in IOP (−8%) and antiglaucoma medications (−77%), with 83% of eyes remaining medication-free at 12 months. 19 The most frequent complication observed was stent occlusion by iris (10%; n=3). 19 Prospective studies have shown that iStent inject implantation combined with phacoemulsification has a minimal effect on corneal endothelial cell loss (CECL).…”

“… 19 The most frequent complication observed was stent occlusion by iris (10%; n=3). 19 Prospective studies have shown that iStent inject implantation combined with phacoemulsification has a minimal effect on corneal endothelial cell loss (CECL). 15 , 20 , 21 In the iStent inject pivotal trial, Samuelson et al reported CECL percentages of −13.1% and −12.3% in eyes receiving phacoemulsification-alone and phacoemulsification-iStent inject surgery, respectively, with a comparable CECL >30% observed in both groups at 24 months (10.4% vs 9.5%).…”