Take-home message: The use of multiple second-generation stent systems led to a 20% or higher reduction in IOP in a group of patients with mild-to-moderate, open-angle glaucoma.
By Vanessa Caceres; Reviewed by Richard L. Lindstrom, MD
—Implantation of two second-generation stents as a stand-alone procedure helped a group of patients with glaucoma reduce IOP to 15 mm Hg or less, said Richard L. Lindstrom, MD.
This IOP reduction occurred without the use of postoperative medications for 18 months. Patients had open-angle glaucoma (OAG) and a mean IOP of 19 mm Hg on one preoperative medication, said Dr. Lindstrom, MD, adjunct professor emeritus, University of Minnesota, Minneapolis.
About the study
Dr. Lindstrom was one of a large group of physicians from around the globe who took part in the study, based at a study center in Armenia. The prospective, single-arm, open-label study included 57 patients with mild-to-moderate OAG with a medicated IOP of 18 to 30 mm Hg and an unmedicated IOP of 22 to 38 mm Hg. Patients had best-corrected visual acuity (BCVA) of 20/100 or better.
Study investigators aimed to measure at month 12 the number of patients with an IOP that was reduced by 20% or more compared with their baseline IOP without medication. A secondary outcome was an IOP of 18 mm Hg or less without medication, Dr. Lindstrom said. Investigators also evaluated safety.
The device used in the study (iStent Inject Trabecular Micro-Bypass Stent System) is a second-generation device not yet approved by the FDA, although it has a CE Mark in Europe.
The single-piece, titanium micro-bypass stent is implanted ab internally through a temporal corneal incision. As the idea is to implant two of the stents for better IOP control, as is already done in some parts of the world, physicians can use an inserter with two pre-loaded stents. The procedure was performed without cataract surgery.
“Around the world, physicians have found that the placement of two or three stents gives a greater effect than what’s approved in the United States,” Dr. Lindstrom said. “Also, the next-generation product is a simpler stent to place.”
Of the 57 patients, 27 were women, and all were white. The mean age was 65.3 years. Patients used an average of one medication before the procedure, and the mean IOP with medication was 19.5 mm Hg. The unmedicated IOP was 24.4 mm Hg. The most common type of medication used was a prostaglandin analogue
By month 12, 100% of patients had a 20% or greater decrease in their preoperative unmedicated IOP, Dr. Lindstrom said.
Seventy-five percent had a 20% or greater decrease compared with preoperative medicated IOP. Without medication, 100% had an IOP of 18 mm Hg or lower, and 67% had an IOP of 15 mm Hg or lower.
An analysis of the mean IOP through month 18 reveals the IOP-lowering trends, Dr. Lindstrom said.
Although the mean IOP increased to 24.4 mm Hg right after the washout period—when patients stopped using their medications—it dropped down to 14.3 mm Hg at month 1 and then ended at 14.4 mm Hg at month 18.
“That was a 41% decrease from the preoperative unmedicated IOP,” Dr. Lindstrom said.
There were no major safety issues in the study; one patient had a loss of BCVA because of a cataract progression. At month 18, 93% of patients had BCVA of 20/40 or better.
The study did have some limitations, Dr. Lindstrom said.It was open label, there was no control group, and all patients were white.
Additionally, the qualifying IOP was not measured on multiple days. However, the study showed overall good outcomes and safety, Dr. Lindstrom said.
He added that although the second-generation device is not yet available in the United States, it should be eventually approved and used here.
Richard L. Lindstrom, MD
E: [email protected]
This article was adapted from Dr. Lindstrom’s presentation at the 2016 meeting of the American Society of Cataract and Refractive Surgery. Dr. Lindstrom is a consultant for and equity owner in Glaukos.