Micro-bypass stent implant during cataract surgery: lower IOP, fewer medications

Reviewed by Mark Gallardo, MD

Mark Gallardo, MD, reported that evaluation of the iStent inject (Glaukos) showed that the device achieved substantial reductions in both intraocular pressure (IOP) and use of anti-glaucoma medications when combined with phacoemulsification cataract surgery in patients with open-angle glaucoma (OAG). He is in private practice at El Paso Eye Surgeons, El Paso, TX.

The first generation of the this trabecular bypass showed well-established performance and safety in OAG and the second generation is currently being used worldwide.

The iStent inject has 2 stents, each of which has 4 side outlets that are designed to access up to 6 clock hours of collector channels, Gallardo explained.

“The iStent inject may reestablish outflow in previously dormant channels,” he commented.

Evaluating the device
Gallardo and Scott Wolf, MD, also from El Paso Eye Surgeons, conducted a retrospective single-center analysis of the patient data from 103 eyes at 12 months postoperatively to evaluate the changes in the mean IOP and mean number of medications; some patients had been followed out to 24 months.

More than two-thirds of the study population was Hispanic, and most patients had moderate glaucoma.

The mean baseline IOP was 16.5 mmHg with patients on 1.7 anti-glaucoma medications. Twelve percent of eyes had undergone a previous glaucoma surgery.

The study was comprised of 2 treatment groups, i.e., 53 eyes in which the IOP was controlled by a mean of 1.85 medications to 18 mmHg or lower and 50 eyes in which the IOP was not controlled with 1.62 medications with IOPs exceeding 18 mmHg.

The goal in the controlled group was reduction of the medication burden and that in the uncontrolled group was reduction of IOP, Dr. Gallardo recounted.

Results
The results in the eyes with controlled IOP showed significant (p<0.001) medication reductions at months 6, 9, 12, and 24.

The numbers of medications decreased by from 63% to 97% over the 24-month course; 69% to 97% of eyes were medication-free over the 24 months compared with 6% preoperatively, Gallardo reported.

In the group with uncontrolled IOP, significant (p<0.001) decreases in the IOP also were seen at the same time points as in the controlled group.

The IOPs decreased by from 26% to 36% over 24 months and the medication burden decreased by from 39% to 82%.

The safety profile was favorable with transient IOP increases that resolved with medication. Two eyes underwent another glaucoma procedure, selective laser trabeculoplasty and XEN surgery. No eyes needed a traditional filtration surgery.

The investigators concluded that that significant IOP and medication reductions were achieved as seen with the real-world use of the iStent inject, and the safety profile was good.

Gallardo pointed out that the study provided “much-needed data from a predominantly Hispanic population” and that the findings added to the existing data that indicated that this device is an efficacious, durable, and safe treatment for OAG.

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Mark Gallardo, MD
E: gallardomark@hotmail.com
This article is adapted from Dr. Gallardo’s presentation at the American Society of Cataract and Refractive Surgery, July 25, 2021. He is a consultant, speaker, and clinical investigator for Glaukos.