Nancy A. Melville

May 28, 2014

ORLANDO, Florida — In patients with primary open-angle glaucoma who have failed to respond to medication, microinvasive glaucoma surgery with the CyPass Micro-Stent (Transcend Medical) is safe and can lead to a sustained reduction in intraocular pressure, a new study shows.

"This as an important option for patients who were looking at trabeculectomy," said lead investigator Randy Craven, MD, associate professor of ophthalmology at the Wilmer Eye Institute, Johns Hopkins School of Medicine, in Baltimore, Maryland.

"It does seem to have a low risk associated with it, and it potentially provides patients with an option aside from a filtering procedure to control the pressure," he added.

The stent is implanted into the supraciliary space through a 1.5 mm corneal incision, Dr. Craven explained.

"The implantation is similar to the iStent," he said. "The device is placed across the anterior chamber and you make a small cleft into the supraciliary space and place the device into the suprachoroidal space."

Dr. Craven presented results from the multicenter, single-group DUETTE study here at Association for Research in Vision and Ophthalmology 2014 Annual Meeting.

The 65 patients implanted with the CyPass microstent had primary open-angle glaucoma and were refractory to topical glaucoma therapy.

At baseline, 69% of the patients were taking 2 or more medications, and all had medicated intraocular pressure levels of at least 21 mm Hg (mean, 24.5 mm Hg).

At 12 months, results were available for 47 patients.

Overall, there was a 32% reduction in pressure from baseline (P < .0001), to a mean of 16.7 mm Hg. In addition, medication use declined from a mean of 2.2 drugs at baseline to 1.5 at 12 months (P = .008).

The procedure had a good safely profile, with no retinal complications, hypotony maculopathy, bleb-related complications, or suprachoroidal hemorrhage.

Currently, the US Food and Drug Administration requires that microinvasive glaucoma surgery be performed in combination with cataract surgery.

"This, in my opinion, is missing a significant number of patients who will benefit from the procedure," Dr. Craven told Medscape Medical News.

The ability to perform such surgery on its own "could be critically important in an array of patient cases," he explained. An example could be a pseudophakic patient with clear contraindications to either filtration or tube surgery, such as someone taking warfarin.

"If you have risks, why not do the procedure that has less morbidity?" he asked.

Dr. Craven emphasized that patient selection is key to the procedure's success. In this study, intraocular pressure ranged from 21 to 35 mm Hg in patients who were taking 1 to 4 pressure-lowering medications.

He added that patients "could be pseudophakic or phakic with a need to lower pressure because medication options were exhausted, or close to that."

Patients were ineligible for the procedure if they had glaucoma that was acute-angle closure, traumatic, congenital, malignant, uveitic, or neovascular, or if they had undergone previous incisional glaucoma surgery or any combined cataract-glaucoma procedure.

"Basically, we took patients who might have undergone a trabeculectomy and did the CyPass instead," Dr. Craven explained.

Microinvasive glaucoma surgery is a great option when safety is more desirable than pressure reduction, "or when you don't mind adding a medication to help get the intraocular pressure to the level you want," he added.

"For me, that fits with a lot of my patients. I am bullish on this procedure. I bet that someday it will surpass filtration procedures. I have been doing it for almost 10 years now," he said, and if there were serious risks, "there would have been some problem surface by now with the iStent, Hydrus, or CyPass."

"Microinvasive glaucoma surgery used outside of combined surgery may, in my opinion, be our largest service to the glaucoma patient community," he said.

There are potential benefits with standalone microinvasive glaucoma surgery, agreed Shlomo Melamed, MD, PhD, professor of ophthalmology at Tel Aviv University in Israel, who attended the presentation.

"I think the take-home message from this is that glaucoma surgeons shouldn't be afraid of the supraciliary space anymore," he said.

"There have been many studies showing similar results and we haven't seen any significant problems, so we should have confidence in this," Dr. Melamed pointed out.

Dr. Craven reports that he is a consultant with Glaukos and Transcend Medical. Dr. Melamed has received grants for clinical investigations from IOPtima, Allergan, Eyetechcare, Solx, and Ellex.

Association for Research in Vision and Ophthalmology (ARVO) 2014 Annual Meeting: Abstract 821. Presented May 5, 2014.



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