Lara C. Pullen, PhD

May 03, 2012

May 3, 2012 (Chicago, Illinois) — The second-generation GTS400 stent has a high intraoperative reliability, and appears to be safe and effective, with a postoperative decrease in intraocular pressure (IOP) and medications.

Steven D. Vold, MD, from VoldVision in Fayetteville, Arkansas, reported the results of a prospective randomized controlled multicenter study here at the American Society of Cataract and Refractive Surgery 2012 Symposium on Cataract, IOL and Refractive Surgery. The study described the implantation of the GTS400 stent using the G2-M-IS injector (Glaukos Corp.).

The primary outcome measure of the study was a reduction in IOP of at least 20%. The secondary outcome measure was a diurnal IOP reduction from baseline.

To be eligible for the study, patients had to be older than 45 years, had to have mild to moderate open-angle glaucoma with characteristics consistent with mild/moderate glaucoma, and had to be using 1 to 3 medications at the time of the screening exam.

Exclusion criteria included pigmentary or psudoexfoliative glaucoma and previous incisional glaucoma surgery.

The researchers compared stent implantation in conjunction with cataract surgery and cataract surgery alone. The single-piece heparin-coated titanium stent was implanted internally in the Schlemm's canal. Multiple outlet lateral lumens were designed to provide an exit route for aqueous outflow from the anterior chamber.

Ab externo Schlemm's canal surgery is considered a valuable alternative to glaucoma filtration surgery. The trabecular meshwork has an abnormally high resistance to outflow and the surgery reestablishes the physiologic outflow system. The addition of the stent keeps the canal patent and enhances the circumferential flow.

The G2-M-IS injector is designed to deliver 2 GTS400 stents with 1 insertion instrument using the same clear corneal incision as in cataract surgery.

Dr. Vold described the stent as easy to use. "Really, in a matter of seconds you can insert it." He also explained that "the goal when you are doing this is to get them close to the collector channel."

In his presentation, Dr. Vold described a series of uncomplicated surgeries that involved 100 eyes (35 male and 65 female) implanted with 2 GTS400 stents. Of these, 90 eyes underwent stent implantation alone and 10 eyes underwent concomitant cataract surgery. To date, 34 eyes have been followed 6 months postoperatively.

IOP Was Reduced After Stent Implantation

The baseline IOP was 23.9 ± 1.6 mm Hg on an average of 1.8 medications. Six-month IOP (for 34 eyes) was 15.1 ± 2.8 mm Hg on a mean of 0.3 medications. There were no reports of an IOP increase of 10 mm Hg or more from preoperative levels.

One subject reported corneal edema in conjunction with surgery on a dense cataract. No other adverse events were reported.

Reay H. Brown, MD, from Atlanta Ophthalmology Associates in Georgia, moderated the session and spoke with Medscape Medical News about the study. He explained that the second-generation stents are still new and that "this is still a little too early."

Glaucoma is characterized by progressive loss of visual field due to optic nerve damage. It is the leading cause of blindness in the United States, and affects 1% to 2% of people 60 years and older. The management of glaucoma requires lifelong treatment with a spectrum of therapies, including medications, laser treatments, and surgical implants.

Dr. Vold reports being an investigator for Glaukos Corporation. Dr. Brown reports being a consultant for GMP Companies.

American Society of Cataract and Refractive Surgery (ASCRS) 2012 Symposium on Cataract, IOL and Refractive Surgery: Presented April 23, 2012.