Nancy A. Melville

May 12, 2014

BOSTON — In patients with open-angle glaucoma undergoing cataract surgery, the placement of 2 trabecular micro-bypass stents (iStent, Glaukos Corp.) reduced hypotensive medication use and postoperative hyphema formation, compared with ab-interno microcautery trabeculotomy (Trabectome, NeoMedix), new research shows.

"Although both groups in our study showed a decline in intraocular pressure and medication use over 12 months, the stents offer further reduction, as well as a decreased frequency of postoperative hyphema," said investigator Michelle Khan, BSc(Hons), from the School of Medicine at Queen's University in Kingston, Ontario, Canada.

Previous studies have shown the benefit of implanting multiple stents instead of just 1, but this is the first to compare micro-bypass stents with ab-interno microcautery trabeculotomy in combination with cataract surgery.

Khan presented the results here at the American Society of Cataract and Refractive Surgery 2014 Symposium.

The investigators evaluated patients undergoing phacoemulsification. The procedure was combined with the implantation of 2 trabecular micro-bypass stents in 49 patients and with ab-interno micro-cautery trabeculotomy in 52 patients.

There were no significant differences in preoperative intraocular pressure or medication use in the 2 groups, and none of the patients dropped out of the study.

Patients in both groups experienced a slight increase in pressure in week 1 of the study, but declines became steady during follow-up.

A 12 months, intraocular pressure was significantly lower in both groups. However, the reduction in pressure was significantly greater in the stent group than in the trabeculotomy group (5.2 vs 3.78 mm Hg; P = .008).

In addition, the use of topical ocular hypotensive medication was lower in the stent group (P < .01).

More patients in the stent group than in the trabeculotomy group achieved an intraocular pressure below 18 mm Hg without medication (39% vs 14%; = .03).

There were no differences between the groups in terms of pressure spikes or interventions; however, the stent group had significantly lower rates of hyphema (P = .008).

"These results not only confirm previous literature showing a decrease in intraoperative pressure and medications with each of these methods, they provide new information," Khan reported. "Cataract surgery combined with 2 stents results in significantly lower intraocular pressure, decreased medication use, and decreased frequency of postoperative hyphema formation."

This isn't the first study to find more benefits with 2 stents, but the comparison with ab-interno microcautery trabeculotomy is notable, said session moderator Thomas Patrianakos, DO, from the University of Chicago Medical Center.

"The benefits of 2 stents, compared with 1, have been shown in other studies, mostly from Canada. The nice thing about this study is that it shows that 2 stents help lower intraocular pressure more than the only other microinvasive glaucoma surgery procedure approved in the United States — ab-interno microcautery trabeculotomy," he told Medscape Medical News. "There were fewer complications as well."

Dr. Patrianakos added that the larger incision required with trabeculotomy might explain the higher complication rate.

"With trabeculotomy, you're incising about 60 to 120 degrees of the trabecular meshwork, whereas with the stent, you're just inserting it into a small area, so there is less bleeding," he explained. In addition, "the procedure offers a more meaningful reduction in intraocular pressure, faster."

According to Dr. Patrianakos, Glaukos has a new inserter in development that will make the insertion of 2 stents at once easier.

Ms. Khan and Dr. Patrianakos have disclosed no relevant financial relationships. Study investigator Ike K. Ahmed, MD, is on the scientific advisory board for Glaukos.

American Society of Cataract and Refractive Surgery (ASCRS) 2014 Symposium. Presented April 27, 2014.

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