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The SOLX Micro-Shunt: IOP Reduction without a Bleb
The device recently began U.S. trials.
BY CELSO TELLO, M.D.

Lowering IOP is the primary objective in the management of all types of glaucoma. Various degrees of success in achieving this objective are currently provided by pharmaceuticals and laser trabeculoplasty procedures, typically applied as the initial and secondary line of treatment, respectively. When these treatments fail to provide adequate IOP control, surgical intervention typically becomes necessary, with either trabeculectomy or an implantable drainage or filtering device. Due largely to complications arising from surgical blebs, none of these surgical options provide a completely safe and effective solution to the problem of arresting glaucoma-related IOP elevation.

It would be a great benefit to the glaucoma specialist to have an option that could control IOP without the side effects and patient compliance issues of pharmaceuticals, maintain lower IOP for longer periods of time than laser therapy and carry a lower risk of intra- and postoperative complications than current surgical methods. At first glance, a new implantable drainage device, the Gold Micro-Shunt (SOLX, Inc., Boston, Mass.) theoretically appears to offer some, if not all of these benefits.

Clinical trials for the Micro-Shunt recently began in the United States. Here, I will describe the mechanism of action of this device and provide data attesting to its performance.

The Gold Micro-Shunt is a tiny, IOP-lowering implant.

How it Works

Made of 99.9% pure medical-grade gold to provide excellent long-term biocompatibility, the Gold Micro-Shunt (GMS) is approximately 6 mm long, by 3 mm wide and less than 100 μm thick. Implanted through a single 3 mm scleral incision, the GMS is positioned with one end in the anterior chamber and the other in the suprachoroidal space. The eye's natural pressure differential between these two spaces then serves as the mechanism for drawing the aqueous humour from the anterior chamber, through the GMS internal channels and into the suprachoroidal space where it escapes via the eye's natural uveoscleral drainage pathways, rather than being collected in the subconjunctival space or an artificial reservoir. The result is lower IOP without the creation of a bleb or the risk of immediate postoperative hypotony, and the associated postoperative complications.

Approved in Europe

The Gold Micro-Shunt has been approved for sale in Europe for almost a year and is still being investigated in a randomized, multicenter, international clinical trial prior to FDA market clearance. To date, more than 75 patients have been implanted with the GMS worldwide, with the longest follow-up of over 2 years. Initial pressure reductions of up to 16 mm Hg have been seen at 1 day, with average percent reductions of at least 30% at 6 months, 12 months and 24 months reported. Complications have been both minor and infrequent, with the most common being mild hyphema, less than 3 mm, all of which resolved by 1 week postoperatively.

SOLX believes that during advanced stages of glaucoma therapies, the Gold Micro-Shunt presents an attractive alternative to trabeculectomy surgery by providing acceptable clinical results with a procedure that requires less time, demands less skill on the part of the surgeon and has to date demonstrated a lower incidence of complications. The Micro-Shunt can also be used as an earlier therapy as a substitute for glaucoma medication.

Celso Tello, M.D., is affiliated with the New York Eye & Ear Infirmary in New York City.