Micro-shunt demonstrates titratability as minimally invasive IOP-reducer

March 7, 2009

San Diego-A trabecular micro-bypass implant (iStent, Glaukos) helped to reduce IOP effectively in a prospective study of 25 patients. “Multiple [stents] placed in Schlemm’s canal, combined with phacoemulsification, had a significant effect in lowering IOP in this study,” said Ike K. Ahmed, MD, University of Toronto.

San Diego—A trabecular micro-bypass implant (iStent, Glaukos) helped to reduce IOP effectively in a prospective study of 25 patients. “Multiple [stents] placed in Schlemm’s canal, combined with phacoemulsification, had a significant effect in lowering IOP in this study,” said Ike K. Ahmed, MD, University of Toronto.

The implant is made of heparin-coated, surgical-grade titanium. It is implanted through the inner wall of Schlemm’s canal.

Along with phacoemulsification, Dr. Ahmed and his colleagues implanted two of the experimental stents in 14 patients and three of the stents in 11 patients. All of the patients had open-angle glaucoma. Follow-up ranged from 6 months to more than 1 year.

Postoperative IOPs were reduced a similar degree in both groups. For all patients, IOP was reduced from a baseline mean of 20.5 to 13.2 mm Hg. The mean number of anti-glaucoma medications being taken by the patients decreased from a baseline of 2.9 to 1.1. The patients in whom three stents were implanted needed fewer medications than the patients who received two stents.

No serious postoperative complications were identified.

“The [stent] is a promising, low-risk intervention with potential titratability to lower target IOP based on the number of implants,” Dr. Ahmed said. Although these results are encouraging, however, a need exists for larger controlled studies performed without combined phacoemulsifications, possibly looking at diurnal and long-term follow-up, he said.

In a bigger picture, the implant may be part of an evolution in the approach to glaucoma therapy, he said.

“Our traditional approach is to control glaucoma with medications, and we typically reserve surgical therapies such as trabeculectomies or tube shunts until the disease has advanced to a far later stage,” Dr. Ahmed said. “Perhaps these micro-shunts are part of a growing area of what we might term minimally invasive glaucoma surgery, and we might be able to implement these types of therapies for our patients at an earlier stage of the disease.”

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