Glaucoma Well Controlled at 1 Year With CyPass Micro-Stent

Caroline Helwick

November 14, 2012

CHICAGO — For the treatment of primary open-angle glaucoma (OAG), the CyPass Micro-Stent procedure appears safe and effective in lowering intraocular pressure (IOP) for at least 12 months, both as a stand-alone procedure and when done in conjunction with cataract surgery.

"CyPass implantation is a minimally invasive intervention providing sustained IOP control up to 12 months. It is conjunctiva-, sclera- and trabecular meshwork-sparing and can be combined with phaco," said Steven D. Vold, MD, from Vold Vision in Fayetteville, Arkansas, here at the American Academy of Ophthalmology (AAO) 2012 meeting.

The CyPass Micro-Stent is the first microinvasive glaucoma stent designed to reduce IOP by enhancing aqueous outflow to the supraciliary and suprachoroidal spaces. This device, which is 6.35 mm in length with a 300-micron lumen, bypasses the ciliary body by creating a stented micro-cyclodialysis into the supraciliary space. This avoids the trabecular meshwork and Schlemm's canal, which are drainage paths that may be diseased in glaucomatous eyes.

Investigators presented the 1-year results of the CyCLE study, which is evaluating the subchoroidal microstent in 460 patients with OAG. One component is evaluating CyPass alone (n = 222), and the other is combining the procedure with phaco for cataracts (n = 238).

Both studies enrolled patients whose glaucoma was controlled with medications (IOP < 21 mmHg) at baseline and those whose disease was not controlled (IOP 21 mmHg or greater).

Dr. Vold presented the results of the study assessing CyPass Micro-Stent implantation and cataract surgery and Quang H. Nguyen, MD, from Scripps Research Institute, La Jolla, California, presented results for the population undergoing the microstent implantation alone.

Outcomes included adverse complications, change in IOP from baseline during 12-month follow-up, and change in medication usage.

CyPass Plus Phaco

At baseline, mean IOP was 21 mmHg and 37% of patients had IOP of 21 mmHg or greater.

After treatment, patients with uncontrolled IOP experienced a mean IOP reduction from 25.3 mmHg at baseline to 17.2 mmHg at 6 months, which was a 31% improvement, and to 16.3 mmHg at 12 months, a 35% reduction, Dr. Vold reported.

In the cohort with IOP already controlled, pressure was lowered approximately 5% by 6 months and this improvement was sustained in the 16 mmHg range at 12 months, he said.

Use of medications was reduced from an average of 2 per patient at baseline to 1 in the uncontrolled group and to 0.5 in the group controlled at baseline. Moreover, at baseline 36% of patients were receiving at least 2 medications and 31% were on 3 or more, by 12 months this had dropped to 12% and 6%, respectively.

"We saw a remarkable drop of 80% in the number of patients taking 3 or more medications at 12 months," he noted.

The only major serious adverse event was explantation in 0.4% of patients. Other minor complications included the need for additional surgery in 3% of patients, IOP increase in less than 2%, and obstruction in about 5%.

There were no major complications of endophthalmitis, suprachoroidal hemorrhage, retinal detachment, choroid detachment, or flat anterior chamber.

"These preliminary results demonstrate that, when used in combination with cataract surgery, the CyPass Micro-Stent can reduce and stabilize IOP while minimizing the need for glaucoma medications," said Dr. Vold.

"Depending on the quality of the cataract surgery, patients can have 20/20 vision on postop day 1. I have patients out to 3 or 4 years and they are doing very well. For anterior segment surgeons, this is a very appealing surgery," he added.

CyPass as a Stand-Alone OAG Treatment

Dr. Nguyen reported the results of the CyPass Micro-Stent in the 222 patients not having concomitant cataract surgery. More than half the patients had IOP of 21 mmHg or greater at baseline. On average, they were taking 2.4 medications, and 43% had undergone prior invasive interventions for glaucoma.

In the uncontrolled IOP group, mean IPO dropped from 27.4 mmHg at baseline to 18.9 mmHg at 12 months, a 26% reduction. For the group with IOP controlled at baseline, it dropped from a mean of 17.9 mmHg to 16.5 mmHg and remained stable. The average number of medications used was reduced by 33% in the uncontrolled group and by 39% in the controlled group, Dr. Nguyen reported, calling this "a remarkable reduction in the medication burden for these patients."

He highlighted the safety of the procedure. "With this device we don’t see the dreaded complications we see with conventional glaucoma surgery," he said. "We had two explantations. We had no issues with the iris or with endophthalmitis, and we saw few of the lesser complications as well."

Eleven percent of patients needed additional surgery and 7.6% had an increase in IOP; transient inflammation, hypotony and hyphema occurred in less than 3%.

The CyPass will be further evaluated, with phaco versus phaco alone, in the randomized controlled COMPASS trial. Enrolling 505 patients, it is the largest glaucoma device trial to date, Dr. Vold noted.

"These are promising early results. The question is, what will happen later?", said session moderator Robert M. Feldman, MD, professor and chairman, the Ruiz Department of Ophthalmology and Visual Science, The University of Texas Medical School in Houston.

"We are putting this device into the space right next to the most vascular part of the body, the choroid. Previous attempts to go there have looked good early on but have failed later because they scarred down," he noted. "Potentially, we could see this again, but at this time the results look really very promising."

Dr. Vold reported consulting and speakers’ fees for Trascend Medical, Alcon, and AquaSys. Dr. Nguyen reported lecture fees for Alcon, and Dr. Feldman reporting consulting and speaker’s fees for Alcon.

American Academy of Ophthalmology (AAO) 2012. Abstract PA094 and PA095. Presented November 13, 2012.