IStent Inject Device Lowers IOP After Cataract Surgery in Glaucoma Patients

By Lorraine L. Janeczko

April 02, 2019

NEW YORK (Reuters Health) - In patients with mild to moderate glaucoma and cataract, the second-generation iStent inject system, with two redesigned stents, reduces intraocular pressure (IOP) more than cataract surgery alone, according to results of a new pivotal trial.

"The most important finding is that the iStent inject, when done with cataract surgery, can improve the likelihood that unmedicated IOP is reduced by 20% or more compared to cataract surgery alone," Dr. Pradeep Ramulu, a professor of ophthalmology at Johns Hopkins Wilmer Eye Institute in Baltimore, Maryland, told Reuters Health by email.

"Here, two stents were inserted (instead of one with the first-generation device), and the device was re-engineered for easier use and insertion. It was important to know that the new device added value," said Dr. Ramulu, who was not involved in the study.

In the multicenter trial, researchers randomly assigned 118 eyes to no stent and 387 eyes to implantation with the iStent inject Trabecular Micro-Bypass System (Model G2-M-IS from Glaukos Corporation). All eyes had mild to moderate primary open-angle glaucoma (POAG) and preoperative IOP of 24 mmHg or lower on one to three medications, unmedicated diurnal IOP (DIOP) of 21 to 36 mmHg and cataract requiring surgery.

Participants were followed for two years after surgery, and washout of ocular hypotensive medication was performed at months 11 and 23 to enable tests for unmedicated DIOP at months 12 and 24.

At 24 months, 75.8% of treated eyes, compared with 61.9% of control eyes, dropped 20% or more from baseline in unmedicated DIOP (P=0.005), report Dr. Thomas W. Samuelson of Minnesota Eye Consultants in Minneapolis and colleagues in Ophthalmology, online March 14.

The mean drop from baseline in unmedicated DIOP was greater in the treated eyes than in the control eyes (7.0 vs. 5.4 mmHg; P<0.001). Among the responders, 84% of treated eyes and 67% of control eyes were not being given ocular hypotensive medication at 23 months.

Overall, 63.2% of stented eyes compared with 50.0% of control eyes had 24-month medication-free DIOP of 18 mmHg or less.

The overall rate of adverse events was "essentially comparable between groups and considered representative of complications that occur in a similarly aged glaucoma population undergoing cataract surgery," the researchers write.

Dr. Ramulu said these findings are comparable to those reported with the first-generation iStent.

"Of note, over one-third of eyes undergoing cataract/iStent had an untreated IOP above 18, so it is perhaps not an ideal surgery for patients who need/want to be drop-free," he cautioned. "However, it offers a low-risk method to lower IOP and/or medication burden for patients with glaucoma who are undergoing cataract surgery."

Dr. David A. Sola-Del Valle, an instructor in ophthalmology at Massachusetts Eye and Ear and Harvard Medical School in Boston, told Reuters Health by phone, "Anytime we introduce a new device in the market, surgeons look for pivotal studies to make sure the device is safe. It's important to have studies that show that it's safe for the patient and that it's effective."

"Studies in the past have shown that two or three iStents are better than one. But so far, insurance companies have not approved using more than one iStent. So patients have to pay out of pocket for a second or third iStent," Dr. Sola-Del Valle explained. "The iStent inject includes two stents - essentially two additional drainage systems - that are covered by insurance. We will now be able to provide almost every eligible patient with two iStents, which I do think are better than one, without the patient paying high out-of-pocket expenses."

"Treating mild-to-moderate glaucoma patients is moving more and more towards minimally invasive glaucoma surgery because the traditional glaucoma surgeries can have a lot of complications," he noted. "I'm excited that new devices are being introduced into the market for this patient population."

Dr. Samuelson did not respond to requests for comment.

Glaukos provided funding for and participated in all parts of the study, including preparation of the manuscript.


Ophthalmology 2019.