Laird Harrison

April 22, 2015

SAN DIEGO — For a patient with a difficult-to-treat glaucoma, a gelatin stent (Xen, AqueSys) can be effective, new research shows.

"The 1-year results are quite promising," said Davinder Grover, MD, from the University of Texas Southwestern Medical School in Dallas.

He presented the study results here at the American Society of Cataract and Refractive Surgery 2015 Symposium.

In patients whose collector systems cannot be used, the gel stent provides a new drainage pathway, he explained. It is less invasive than trabeculectomy, and postoperative results are more predictable.

The gel stent is currently approved in Europe, but not the United States.

The surgeon uses a 27-gauge double-beveled needle, which tunnels through the sclera, and inserts the stent through a clear corneal incision.

The bevel reduces the risk that the surgeon will pierce the conjunctiva, Dr Grover explained.

After implantation, 1 mm of the 6 mm stent lies in the anterior chamber, 3 mm lies in the intrascleral space, and 2 mm lies in the subconjunctival space.

Dr Grover and his colleagues evaluated the safety and efficacy of the device in 44 European patients who were followed for 12 months after implantation.

All patients were determined by their physicians to have moderate to severe glaucoma. There was no washout period before implantation. Thirty-six of the patients had primary open-angle glaucoma, four had pigmentary glaucoma, and four had pseudoexfoliative glaucoma. Eighteen had undergone previous surgery.

Before implantation, patients were injected with mitomycin 0.1 to 0.2 mL. Previous studies have shown that preoperative low-dose mitomycin significantly reduces postoperative management, the needling rate, the risk for fibrosis, and intraocular pressure.

The stent significantly reduced intraocular pressure and slashed the number of medications patients needed.

Table. Outcomes After Gel Stent Implantation

Measure Before Surgery Day 1 Month 1 Year 1
Mean intraocular pressure, mm Hg 23.0 9.8 14.7 12.9
Change in intraocular pressure, % –54.0 –34.0 –42.0
Number of medications 3.4 0.02 0.3 1.2

 

One year after stent implantation, 45% of the patients were not using any glaucoma medications, Dr Grover reported.

There were some complications. Three patients needed additional surgery, five experienced hypotony of less than 6 mm Hg a day after surgery, eight underwent needling, and one experienced subconjunctival hemorrhage 30 days after the procedure. In addition, one surgeon punctured a patient's conjunctiva.

 
This is a group of patients that is not well served by current operations.
 

Results from this study are "really impressive," said session moderator Reay Brown, MD, from Atlanta Ophthalmology Associates in Georgia.

"They're working on the patients with the worst glaucoma," he told Medscape Medical News. "This is a group of patients that is not well served by current operations."

Other minimally invasive stents usually won't work with these patients because those stents depend on repairing the patient's existing collector system, he explained. In these patients, that system is beyond repair.

The study was funded by AqueSys. Dr Grover is a clinical investigator for AqueSys. Dr Brown reports financial relationships with Glaukos, Ivantis, Rhein Medical, and Transcend Medical.

American Society of Cataract and Refractive Surgery (ASCRS) 2015 Symposium. Presented April 18, 2015.

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