Long-term clinical data are essential for validating the sustained efficacy and safety of glaucoma interventions. A 7-year follow-up study of the iStent inject® (Glaukos) offers compelling evidence that informs clinical decision-making and patient counseling.1
BASELINE CHARACTERISTICS AND PATIENT PROFILES
The study, initiated in 2014, evaluated 125 eyes with a mean preoperative IOP of 23.5 ±6.2 mm Hg (Figure 1). Despite an average use of 2.7 ±1.0 antiglaucoma medications, these patients were not achieving target IOP control, which highlights the limitations of pharmacologic therapy alone. The cohort was composed of 78% patients with primary open-angle glaucoma (POAG), with a smaller proportion of patients with pseudoexfoliative glaucoma (15%) and other forms of glaucoma (7%). Additionally, 38% of the patients had undergone previous glaucoma surgeries, including cyclophotocoagulation, trabeculectomy, and selective laser trabeculoplasty. The presence of prior surgeries and high preoperative medication burden suggested that these were complex cases requiring alternative interventions.
Figure 1. Baseline characteristics and prior interventions of study participants.
Of the patients, 65% underwent the iStent inject® procedure in combination with cataract surgery, allowing for the evaluation of outcomes in both standalone and combined settings.
LONG-TERM IOP AND MEDICATION REDUCTION
The iStent inject® system provided consistent and sustained IOP reduction throughout the 7-year follow-up. The average IOP decreased from 23.5 mm Hg preoperatively to 14.1 mm Hg at year 7, representing a 40% reduction. Medication burden also decreased significantly, with a 59% reduction in the number of medications required at 7 years (Figure 2). The average medication count dropped from 2.7 preoperatively to 1.1 at the 7-year mark, with many patients achieving adequate IOP control on a single medication or no medications at all. This outcome reflects the device’s ability to provide durable IOP control while minimizing dependence on pharmacotherapy.
Figure 2. Long-term IOP and medication reduction over 7 years.
Importantly, these results were consistent regardless of whether the iStent inject® was used as a standalone procedure or in combination with cataract surgery. The 81 eyes that underwent a combined procedure and the 44 eyes treated with the iStent inject® alone demonstrated sustained IOP control, reinforcing the flexibility of this device in different clinical scenarios.
SAFETY PROFILE AND EASE OF USE
The iStent inject® demonstrated a favorable safety profile, with no significant complications reported over the 7-year follow-up period. None of the patients required filtration surgery, and there were no instances of peripheral anterior synechiae, hypotony, endophthalmitis, choroidal hemorrhage, or stent dislocation.
The procedure itself is minimally invasive and straightforward, involving the placement of two stents approximately 2 clock hours apart to maximize outflow through the Schlemm canal. Visualization of the stent location with methylene blue dye can provide immediate feedback on the accuracy of the placement.
ARE TWO STENTS ENOUGH?
Randomized controlled trials have shown that two stents strike a balance between efficacy and safety in patients with mild-to-moderate POAG.2 For the majority of patients, two stents are sufficient to achieve significant and sustained IOP reduction while keeping 98% of the trabecular meshwork intact (data on file with Glaukos). This approach minimizes the risk of complications and preserves the safety profile of the procedure (data on file with Glaukos).
A meta-analysis of 15 studies involving over 1,100 eyes demonstrated the effectiveness of iStent® technologies in slowing visual field progression in patients with mild-to-moderate POAG.3
CONCLUSION
The 7-year data on the iStent inject® reinforce its role as an effective and durable treatment for reducing IOP and minimizing medication dependence in patients with mild-to-moderate POAG. The fact that the device is implanted in a minimally invasive procedure and its excellent safety profile make it an attractive option for early intervention in the glaucoma treatment continuum.
1. Hengerer FH, Auffarth GU, Conrad-Hengerer I. 7-Year efficacy and safety of iStent inject trabecular micro-bypass in combined and standalone usage. Adv Ther. 2024;41(4):1481-1495.
2. Katz LJ, Erb C, Carceller Guillamet A, et al. Long-term titrated IOP control with one, two, or three trabecular micro-bypass stents in open-angle glaucoma subjects on topical hypotensive medication: 42-month outcomes. Clin Ophthalmol. 2018;12:255-262.
3. Gillmann K, Hornbeak DM. Rates of visual field change and functional progression in glaucoma following trabecular microbypass implantation of iStent technologies: a meta-analysis. BMJ Open Ophthalmol. 2024;9(1):e001575.
INDICATIONS FOR USE: The iStent® Trabecular Micro-Bypass System is intended to reduce intraocular pressure safely and effectively in patients diagnosed with primary open-angle glaucoma, pseudoexfoliative glaucoma or pigmentary glaucoma. The device is safe and effective when implanted in combination with cataract surgery in those subjects who require intraocular pressure reduction and/or would benefit from glaucoma medication reduction. The device may also be implanted in patients who continue to have elevated intraocular pressure despite prior treatment with glaucoma medications and conventional glaucoma surgery. CONTRAINDICATIONS: The iStent® Trabecular Micro-Bypass Stent is contraindicated under the following circumstances or conditions: • In eyes with primary angle closure glaucoma, or secondary angle-closure glaucoma, including neovascular glaucoma, because the device would not be expected to work in such situations • In patients with retrobulbar tumor, thyroid eye disease, Sturge-Weber Syndrome or any other type of condition that may cause elevated episcleral venous pressure. WARNINGS/PRECAUTIONS: For prescription use only. This device has not been studied in patients with uveitic glaucoma. Do not use the devices if the Tyvek® lid has been opened or the packaging appears damaged. In such cases, the sterility of the device may be compromised. iStent is MR-Conditional. Physician training by Glaukos personnel is required prior to use of this device. Do not re-use the stent(s) or inserter, as this may result in infection and/or intraocular inflammation, as well as occurrence of potential postoperative adverse events. There are no known compatibility issues with the iStent and other intraoperative devices (e.g., viscoelastics) or glaucoma medications. Unused product & packaging may be disposed of in accordance with facility procedures. Implanted medical devices and infected products must be disposed of as medical waste.
INDICATIONS FOR USE: The iStent inject® is intended to reduce intraocular pressure safely and effectively in patients diagnosed with primary open-angle glaucoma, pseudo-exfoliative glaucoma or pigmentary glaucoma. The iStent inject® can deliver two (2) stents on a single pass, through a single incision. The implant is designed to stent open a passage through the trabecular meshwork to allow for an increase in the facility of outflow and a subsequent reduction in intraocular pressure. The device is safe and effective when implanted in combination with cataract surgery in those subjects who require intraocular pressure reduction and/or would benefit from glaucoma medication reduction. The device may also be implanted in patients who continue to have elevated intraocular pressure despite prior treatment with glaucoma medications and conventional glaucoma surgery. CONTRAINDICATIONS: The iStent inject® System is contraindicated under the following circumstances or conditions: • In eyes with primary angle closure glaucoma, or secondary angle-closure glaucoma, including neovascular glaucoma, because the device would not be expected to work in such situations • In patients with retrobulbar tumor, thyroid eye disease, Sturge-Weber Syndrome or any other type of condition that may cause elevated episcleral venous pressure. WARNINGS/PRECAUTIONS: • For prescription use only. • This device has not been studied in patients with uveitic glaucoma. • Do not use the devices if the Tyvek® lid has been opened or the packaging appears damaged. In such cases, the sterility of the device may be compromised. • Due to the sharpness of certain injector components (i.e. the insertion sleeve and trocar), care should be exercised to grasp the injector body. Dispose of device in a sharps container. • iStent inject® is MR-Conditional; see MRI Information below. • Physician training is required prior to use of the iStent inject® System. • Do not re-use the stent(s) or inserter, as this may result in infection and/or intraocular inflammation, as well as occurrence of potential postoperative adverse events as shown below under “Potential Complications.” • There are no known compatibility issues with the iStent inject® and other intraoperative devices (e.g., viscoelastics) or glaucoma medications. • Unused product & packaging may be disposed of in accordance with facility procedures. Implanted medical devices and contaminated products must be disposed of as medical waste. • Due to the sharpness of certain injector components (i.e. the insertion sleeve and trocar), care should be exercised to grasp the injector body • The surgeon should monitor the patient postoperatively for proper maintenance of intraocular pressure. If intraocular pressure is not adequately maintained after surgery, the surgeon should consider an appropriate treatment regimen to reduce intraocular pressure.
INDICATION FOR USE: The iStent inject® W, is intended to reduce intraocular pressure safely and effectively in patients diagnosed with primary open-angle glaucoma, pseudo-exfoliative glaucoma or pigmentary glaucoma. The iStent inject® W, can deliver two (2) stents on a single pass, through a single incision. The implant is designed to stent open a passage through the trabecular meshwork to allow for an increase in the facility of outflow and a subsequent reduction in intraocular pressure. The device is safe and effective when implanted in combination with cataract surgery in those subjects who require intraocular pressure reduction and/or would benefit from glaucoma medication reduction. The device may also be implanted in patients who continue to have elevated intraocular pressure despite prior treatment with glaucoma medications and conventional glaucoma surgery. CONTRAINDICATIONS: The iStent inject® W System is contraindicated under the following circumstances or conditions: • In eyes with primary angle closure glaucoma, or secondary angle-closure glaucoma, including neovascular glaucoma, because the device would not be expected to work in such situations. • In patients with retrobulbar tumor, thyroid eye disease, Sturge-Weber Syndrome or any other type of condition that may cause elevated episcleral venous pressure. WARNINGS/PRECAUTIONS: • For prescription use only. • This device has not been studied in patients with uveitic glaucoma. • Do not use the device if the Tyvek® lid has been opened or the packaging appears damaged. In such cases, the sterility of the device may be compromised. • Due to the sharpness of certain injector components (i.e. the insertion sleeve
and trocar), care should be exercised to grasp the injector body. Dispose of device in a sharps container. • iStent inject® W is MR-Conditional; see MRI Information below. • Physician training is required prior to use of the iStent inject® W System. • Do not re-use the stent(s) or injector, as this may result in infection and/or intraocular inflammation, as well as occurrence of potential postoperative adverse events as shown below under “Potential Complications.” • There are no known compatibility issues with the iStent inject® W and other intraoperative devices. (e.g., viscoelastics) or glaucoma medications. • Unused product & packaging may be disposed of in accordance with facility procedures. Implanted medical devices and contaminated products must be disposed of as medical waste. • The surgeon should monitor the patient postoperatively for proper maintenance of intraocular pressure. If intraocular pressure is not adequately maintained after surgery, the surgeon should consider an appropriate treatment regimen to reduce intraocular pressure. • Patients should be informed that placement of the stents, without concomitant cataract surgery in phakic patients, can enhance the formation or progression of cataract. ADVERSE EVENTS: Please refer to Directions For Use for additional adverse event information. CAUTION: Please reference the Directions For Use labelling for a complete list of contraindications, warnings and adverse events.
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