Impressive IOP results from second-generation microinvasive surgery

Reviewed by Fritz Hengerer, MD, PhD

TAKE HOME MESSAGE: Follow-up to one year for a consecutive series of 29 eyes with open-angle glaucoma and IOP uncontrolled by medication and/or surgery show impressive IOP lowering and reduction of medication use after implantation of two second-generation trabecular micro-bypass stents.

Frankfurt, Germany-Implantation of two second-generation trabecular micro-bypass stents (iStent inject, Glaukos) as a single procedure or combined with cataract surgery is a safe and effective option for reducing IOP and the medication burden in eyes with open-angle glaucoma and IOP uncontrolled by medication and/or surgery, according to German surgeons.

Analyses of outcomes from a consecutive series of 29 eyes (22 patients) that underwent the glaucoma surgery showed mean medicated IOP was reduced from 24.3 mm Hg at baseline to 14.8 mm Hg at three months when 27 eyes were available for follow-up.

Among 22 eyes evaluated at one year, mean IOP was 13.8 mm Hg (–43% change from baseline). Mean daily medication use was reduced by 86% from 2.8 at baseline to 0.6; 45% of patients were on no medications, 50% were using a single agent, one patient was on two medications, and no one was using more than two medications.

There were no intraoperative sequelae, and during follow-up to one year, safety remained excellent, said Fritz Hengerer, MD, PhD, deputy director and senior head physician, Goethe University, Frankfurt, Germany.

“All implantations were completed without endothelial or lens contact or other untoward events,” he said. “Follow-up is continuing and is now approaching 18 months. Visual acuity has remained stable and IOP is also being maintained close to the 12-month level.”

Improving aqueous outflow

The second-generation trabecular micro-bypass stent procedure improves aqueous outflow. The stent itself is smaller than the first-generation device and shaped differently. The two stents come preloaded on a single-use, sterile injector and are delivered into Schlemm’s canal through a clear cornea microincision under gonioscopic control.

“The second-generation stent features a central inlet and four outlets that optimize flow and collector channel access, ” Dr. Hengerer said. This redesign-together with implantation of two stents-increases the likelihood of achieving greater reduction in IOP compared with implantation of a single first-generation stent.

“Implantation is also easier with the second-generation stent procedure,“ he added. “Now, implantation does not require a lateral movement of the stent into Schlemm’s canal.“

Rather, it is completed by simply pressing the trigger button on the delivery device to inject the stents through the trabecular meshwork and into Schlemm’s canal, where the head of the stent sits securely with the thorax of the stent held by the meshwork, he noted.

The 22 patients with the two second-generation stents implanted had a mean age of about 71 years at baseline. 24 of the 29 eyes (83%) had been on three or four medications preoperatively, and 11 (38%) had prior glaucoma surgery, including trabeculectomy in five eyes. Mean cup-disc ratio was 0.8. The stents were implanted as a sole procedure in 17 eyes (59%) and during cataract surgery in 12 eyes (41%).

Preoperatively, best-corrected visual acuity (BCVA) was 20/40 or better in 76% of eyes and 20/25 or better in 21%. Among 22 eyes evaluated at the 6-month visit, BCVA was 20/40 or better in 86% and 20/25 or better in 33%.

“The only event that occurred was cataract progression in two of the phakic eyes related to the natural course of cataract development due to patients age,” Dr. Hengerer said.

Fritz Hengerer, MD, PhD

E: fritz.hengerer@kgu.de

This article was adapted from Dr. Hengerer’s poster presentation at the 2015 meeting of the American Academy of Ophthalmology. Dr. Hengerer has no financial interest in the device he discussed or its manufacturer.