Premium Surgical Comanagement: Introducing iStent inject W

Increasing numbers of cataract patients are investing in premium intraocular lenses (IOLs), seeking excellent visual outcomes and reduced spectacle dependence. However, growing numbers of these patients also have glaucoma.

Surgeons can target both issues during cataract surgery by implanting the new iStent inject W (Glaukos) trabecular micro-bypass system, an FDA-approved device used to treat increased intraocular pressure (IOP) in adults with mild to moderate primary open-angle glaucoma.

Mechanism of Action

Featuring a unique mechanism of action and microinvasive design, the iStent inject W creates two openings through the trabecular meshwork, reestablishing multidirectional flow through Schlemm’s canal without unnecessarily disrupting the outflow system.

The tiny ab interno micro-bypass system, which is only 360 µm long and 360 µm in diameter, has a wide flange at the base of the stent that makes it easier to see, enhances implantation, allows the surgeon to visually confirm positioning, and provides predictability and consistency.

Safety and Efficacy

The iStent inject W is based on the previously approved iStent inject (Glaukos), which has shown excellent safety similar to that of cataract surgery alone.¹ Endothelial cell loss (ECL) and peripheral anterior synechiae were lowest for iStent inject compared with other trabecular bypass minimally invasive glaucoma device pivotal trials.^1*†

Immediately after the iStent inject was implanted, aqueous angiography showed that aqueous outflow was more expansive and the arcs of flow could span 5 to 6 clock hours.² In addition, flow may be restored in channels that were inactive.

IOP and medication burden decreased significantly after patients received the iStent inject, and a significant number of articles in the literature have reported sustained reduction of IOP and medication in patients receiving the iStent inject (Figure 1).^3-10

Postoperative Refractive Outcomes

The iStent inject W offers numerous advantages in patients choosing premium IOLs who have high expectations of their postoperative visual outcomes.

Compared with traditional glaucoma filtering procedures, trabecular micro-bypass stenting can effectively treat mild to moderate open-angle glaucoma without impacting the patients’ postoperative vision.

The iStent inject W platform is refractively neutral when implanted during cataract surgery.¹¹ In 106 eyes of 89 patients, Ioannidis and associates reported the mean absolute difference from target refraction was 0.36 ± 0.25 D; 73.9% of eyes were within ± 0.50 D and 98.9% within ± 1.00 D of the refractive target. After surgery, 73.8% of eyes had 0.50 D or less residual astigmatism.

Almost 60% of patients with glaucoma have described OSD symptoms, which can impact visual outcomes of cataract surgery.¹² OSD may be caused by their age, long-term medications, and using multiple ophthalmic medications (Figure 2). In addition, these patients also may have had glaucoma filtering surgery, which can impact healing.

Research has shown that patients using more topical glaucoma medications (with and without benzalkonium chloride) were more likely to have an abnormal tear breakup time.¹³ The tear film may be preserved, and refractive outcomes may improve if patients reduce their use of glaucoma medications, often containing preservatives such as benzalkonium chloride which have been associated with OSD.¹⁴

A multicenter study of 47 eyes reported significant improvements in Ocular Surface Disease Index (OSDI) scores and reduced IOP and medication use 3 months after stent implantation.^15,16 In addition, 49% of eyes had longer tear film breakup times, reduced corneal and conjunctival staining, and an improved hyperemia trend.

In the iStent inject pivotal trial, 84% of those who responded to implantation of the device plus phacoemulsification were not using glaucoma medications 23 months after surgery.¹

Analyzing pivotal trial data, which included patient-reported outcomes using the Visual Function Questionnaire (VFQ-25) and OSDI, Thomas Samuelson, MD, found that iStent inject with cataract surgery may improve ocular symptoms and vision-related activities compared with cataract surgery alone.¹⁷ The iStent inject pivotal trial demonstrated significant sustained vision-related quality of life improvements. General vision, ocular pain, driving subscales, and other measures improved significantly.

Practice Impact

The iStent inject W streamlines glaucoma treatment and can be easily integrated into cataract comanagement. Reduced IOP may help prevent glaucoma progression and reduce the need for a second, more invasive, surgery. In research Dr. Samuelson presented, IOP-related secondary surgical intervention was performed in 1% of eyes implanted with the iStent inject compared with 3% of those treated with phacoemulsification (Figure 3).¹⁸

Figure 3. Kaplan Meier graph of days from surgery to first IOP-related secondary surgical intervention.¹⁸ Credit: Thomas Samuelson, MD

In my experience, patients have a low complication rate, and the platform for the iStent inject W has been proven to be safe and effective. Postoperative care after implantation of iStent inject is similar to that for cataract surgery. We do not need to use long-term topical steroid medications for lengthy periods of time like we do after other filtering tubes and trabeculectomy procedures.

Patients choosing premium IOLs have high expectations of their postoperative visual outcomes. The iStent inject W is a useful technology in these patients, based on a platform with clinically proven IOP reduction, potential to decrease glaucoma medications, clinically proven refractive outcomes, and the potential to reduce the impact of OSD.