Long-term outcomes of two first-generation trabecular micro-bypass stents (iStent) with phacoemulsification in primary open-angle glaucoma: eight-year results

Abstract

Background The short- and medium-term outcomes of iStent have been extensively studied; however, only few studies have investigated its long-term outcomes. Here, we assessed the long-term efficacy and safety of two iStents with concomitant cataract surgery in glaucomatous eyes while also evaluating measures of disease stability using visual field and optical coherence tomography (OCT) of the optic nerve and the macula throughout 8 years of follow-up. Methods This longitudinal, single-center consecutive case series included glaucomatous eyes that underwent implantation of two first-generation trabecular micro-bypass stents (iStent) with concomitant cataract surgery. Eight-year efficacy outcomes included mean intraocular pressure (IOP) and medications, as well as surgical success. Eight-year safety outcomes included best-corrected visual acuity (BCVA), visual field mean deviation (VF-MD), cup-to-disc ratio (CDR), retinal nerve fiber layer (RNFL) thickness, ganglion cell-inner plexiform layer (GC-IPL) thickness, and adverse events. Results A total of 62 eyes with primary open-angle glaucoma (POAG) were included. At 8 years postoperative, IOP reduced by 26% from 19.2 ± 3.9 mmHg preoperatively to 14.2 ± 2.4 mmHg (P < 0.001), 91.1% of eyes achieved IOP ≤ 18 mmHg (vs. 51.6% preoperatively), 69.6% of eyes achieved IOP ≤ 15 mmHg (vs. 14.5% preoperatively), and 25% of eyes achieved IOP ≤ 12 mmHg (vs. 1.6% preoperatively). Medication use decreased by 17.9% from 2.8 ± 1.1 preoperatively to 2.3 ± 1.2 (P = 0.018). Surgical success was 90%, as six eyes underwent subsequent glaucoma surgeries. Safety measures of BCVA, CDR, RNFL thickness and GC-IPL thickness remained stable through 8 years postoperative. VF-MD remained stable until postoperative year 5 and subsequently progressed according to the natural history of glaucomatous disease. Conclusions Implantation of two iStents with concomitant cataract surgery is an effective and safe treatment option for surgery-naïve POAG eyes, evidenced by significant IOP and medication reductions, reasonable surgical success, and favorable safety outcomes, throughout the 8-year follow-up. Our data additionally supports the efficacy of this combined procedure in stabilizing or slowing disease progression.

Effectiveness and Safety of iStent Infinite Trabecular Micro-Bypass for Uncontrolled Glaucoma

“…This was a single-arm, open-label trial, consistent with FDA standards for a 510(k) device registration submission. Although the follow-up period of 12 months is of relatively short duration, the iStent infinite has the same mechanism of action and treatment approach as the first-generation iStent and second-generation iStent inject devices, which have shown consistent durability in maintaining IOP and medication reductions for up to 8 years postoperative 16–18,20–32,37–39. Hence, long-term studies with iStent infinite would be expected to demonstrate similarly consistent effectiveness and safety over time.…”

“…17,18 Beyond the pivotal trials evaluating combined procedures for mild to moderate primary OAG, multiple additional studies have shown that implantation of iStent and iStent inject can effectively and safely reduce IOP and medication burden in both combined (with phacoemulsification) and stand-alone (without phacoemulsification) surgery. [20][21][22][23][24][25][26][27][28][29][30][31][32] The evidence also demonstrates an incremental increase in IOP-reducing and medication-reducing effect with a higher number of iStents (1 vs. 2 vs. 3) 20,[33][34][35][36][37][38][39] and suggests a specific incremental benefit of 3 over 2 stents. 16 Subconjunctival bleb-associated surgeries, which bypass the eye's natural drainage system and create a filtering bleb (eg, trabeculectomy, tube shunt implantation, XEN Gel Stent implantation, Preserflo), may be considered when greater IOP lowering is required.…”

“…Although the follow-up period of 12 months is of relatively short duration, the iStent infinite has the same mechanism of action and treatment approach as the first-generation iStent and second-generation iStent inject devices, which have shown consistent durability in maintaining IOP and medication reductions for up to 8 years postoperative. [16][17][18][20][21][22][23][24][25][26][27][28][29][30][31][32][37][38][39] Hence, long-term studies with iStent infinite would be expected to demonstrate similarly consistent effectiveness and safety over time. No medication washout was done, as this might have placed the enrolled glaucoma patients at undue risk for optic nerve damage.…”

“…In the United States, all 3 devices are indicated for use in mild to moderate OAG in combination with cataract surgery, supported by randomized controlled pivotal trials demonstrating effective IOP lowering and substantial medication reduction;17–19 in the case of iStent and iStent inject, overall safety parameters in these trials were shown to be comparable to cataract surgery alone 17,18. Beyond the pivotal trials evaluating combined procedures for mild to moderate primary OAG, multiple additional studies have shown that implantation of iStent and iStent inject can effectively and safely reduce IOP and medication burden in both combined (with phacoemulsification) and stand-alone (without phacoemulsification) surgery 20–32. The evidence also demonstrates an incremental increase in IOP-reducing and medication-reducing effect with a higher number of iStents (1 vs. 2 vs. 3)20,33–39 and suggests a specific incremental benefit of 3 over 2 stents 16…”

iStent Trabecular Micro-bypass Stent Implantation Combined with Phacoemulsification for Open-Angle Glaucoma: A 2-Year Post-marketing Surveillance Study in Japan

“…It is a titanium, L-shaped stent (1.00 mm by 0.33 mm) that is inserted ab interno into the trabecular meshwork to re-establish flow of the aqueous humor into Schlemm's canal. The iStent, whether combined with cataract surgery or as a standalone procedure, is well tolerated and has demonstrated sustained long-term efficacy in reducing IOP and medication burden significantly in OAG [19][20][21][22][23][24][25][26].…”