By Fred Gebhart
SAN FRANCISCO -- October 27, 2009 -- A single trabecular microbypass stent safely and effectively reduces intraocular pressure (IOP) and drug burden in patients with open-angle glaucoma, researchers stated here at the 2009 Joint Meeting of the American Academy of Ophthalmology and Pan-American Association of Ophthalmology (AAO-PAAO).
"This is a viable procedure and not at all traumatic for the eye," said lead author Carlo Traverso, MD, University Eye Clinic, Genova, Italy, on October 25 during a poster presentation. "It is effective and very, very safe in our experience."
Dr. Traverso and colleagues implanted the trabecular microbypass stent in 45 patients with uncontrolled open-angle glaucoma who were on at least 1 medication. The stent is one of the smallest devices made for implantation, Dr. Traverso said, about 1 mm long by 0.5 mm tall.
All patients had undergone at least 1 prior medical or surgical therapy that had failed or were poor candidates for filtration surgery.
There was no washout period for patients on antihypertensive therapy before the study began, but all patients stopped glaucoma medication immediately following implantation.
Of the original intent-to-treat cohort, 28 patients (62.2%) were available for all 24 months of follow-up.
There are a number of complications inherent in current medical and surgical treatments for glaucoma, Dr. Traverso noted, including hypotony, extrusion, haemorrhage, infection, hyphaema, and cataract.
The stent is designed to bypass the trabecular mesh to connect the anterior chamber directly with Schlemm's canal. The procedure attempts to re-establish physiologic steady-state outflow while leaving the conjunctiva untouched. It also avoids the risk of complications inherent in filtering blebs.
Patients in the study had a mean intraocular pressure of 28.8 mm Hg before the surgery and 17.5 mm Hg at month 24, a mean decrease of 8.7 mm Hg, or 32.8%. Dr. Traverso noted that mean IOP dropped sharply to a mean of 19.3 between implantation and the first follow-up visit at 1 month, then continued to fall slowly and irregularly over the next 23 months.
By month 24, 94.1% of patients had an IOP <21 mm Hg and 43.8% had stopped all glaucoma medications. Overall, patients who received the stent reduced the number of medications from a mean of 2.1 at baseline to 1.2 at 24 months.
There were no severe adverse events associated with the device, Dr. Traverso said, but 17 patients had an IOP >21 mm Hg, defined as failure of the procedure. Of the original cohort, 15 patients required surgical trabeculectomy. Dr. Traverso suggested that the surgical learning curve could be at least partially responsible for a significant portion of adverse events and failures as most were associated with early implantations.
[Presentation title: Refractory Open-Angle Glaucoma: Twenty-Four-Month Results of a Trabecular Microbypass. Abstract PO108]
E-Mail this DGDispatch to a colleague
