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Drainage implant lowers IOP simply and effectively, surgeon says
The Ex-Press miniature drainage implant is a small, less than 3-mm, stainless-steel device that penetrates the sclera at the limbus.
CASTELFRANCO, Italy – The Ex-Press miniature glaucoma implant is an effective, minimally invasive intraocular pressure-lowering device, according to one surgeon.
“It is easy and quick to implant. It creates a bypass between the anterior chamber and the subconjunctival space, allowing for aqueous outflow,” said Giorgio Marchini, MD, at the Advances in Ocular Surgery meeting here.
The Ex-Press (Optonol Ltd.) is made of a stainless-steel alloy. It has a blunt, beveled tip with a principal central hole and three small side holes that maintain ongoing drainage in case of plugging by the iris. A spur on the underside prevents the implant from slipping backwards, and a flat external head that follows the curvature of the sclera prevents the implant from sinking into the eye.
“Its design is similar to that of a little nail. The distance between spur and head is calculated to maintain the implant within the scleral thickness,” Prof. Marchini explained.
Implantation technique
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The implantation technique is simple. A small aperture is made on the conjunctiva, 10 mm from the limbus.
“This incision should be made away from blood vessels, to keep bleeding at a minimum. Then, using a small spatula, the path is opened all the way to the limbus under the Tenon’s membrane. This tunnel ends at the exact point where the Ex-Press will be implanted,” Prof. Marchini said.
A 25-gauge needle is inserted into the anterior chamber to prepare the site for the implant. The device is then driven to its target location by a special inserter and is pushed firmly into the anterior chamber.
“These maneuvers are performed with viscoelastic filling the anterior chamber. In the first 2 to 3 days after surgery, drainage is abundant, and a low-viscosity viscoelastic prevents hypotony and collapsing of the anterior chamber,” he said.
When needed, at the end of the procedure, a small suture can be applied on the conjunctival incision.
“At the beginning of your learning curve, you may find it easier to perform surgical maneuvers from a slightly larger conjunctival incision. However, a 2- to 3-mm incision is considered large enough, and it doesn’t require sutures,” he said.
Good results, few complications
About 200 Ex-Press implants have been performed in various European centers, with a follow-up achieving 2 years in a number of cases, Prof. Marchini said.
“Only three cases of conjunctival erosion and consequent removal of the device have been reported. If the device is correctly implanted, the constant outflow of the aqueous maintains a space between the base of the device and the conjunctiva, thus preventing erosion,” he said.
Other typical complications of filtering surgery, such as choroidal detachment and flat chamber, are rare.
In the first 2 days after implantation, IOP drops to low values, around 5 to 8 mm Hg.
“This is the reason why a low molecular weight viscoelastic must be used during surgery and remain there. If necessary, a refill of the substance can be made at day 1 or 2,” he said.
Mean IOP at 1 year is around 15 mm Hg and remains stable during follow-up intervals.
Phaco Ex-Press combined surgery
The Ex-Press implant is specially indicated in combination with cataract phacoemulsification. “Cataract surgery opens up narrow angles and eliminates the risk of the crystalline lens being damaged by the implant,” Prof. Marchini said.
After traditional phaco has been performed, a suture is applied to the incision, leaving the viscoelastic in the anterior chamber. Then the Ex-Press is implanted.
According to Prof. Marchini, the best position for implantation is in the superotemporal or superonasal quadrant, slightly distant from the 12 o’clock position.
“This leaves one of the superior quadrants always available for filtrating surgery, if needed,” he said.
Patent covered
Prof. Marchini said the mechanism that makes the Ex-Press implant function as a pressure-lowering device is patent-covered and still partly unknown.
“It has holes, but it is not hollow inside. There is something that’s connected with being made of metal, as the manufacturers do not use other materials. The steel alloy is biocompatible and also MRI-compatible,” he said.
“All we know is that it works, and that with some simple maneuvers, minimal invasion and minimal trauma to the conjunctiva, we obtain a good IOP control,” he said.
A note from the editors:
The Ex-Press miniature glaucoma implant is available in countries that use the CE mark. It is not available for sale or use in the United States.
For Your Information:
- Giorgio Marchini, MD, can be reached at Clinica Oculistica, Università di Verona, Ospedale Borgo Trento, P.le Stefani 1, 37126 Verona Italy; (39) 045-807-2340; fax: (39) 045-807-2025; e-mail: oculist@borgotrento.univr.it. Dr. Marchini has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- The Ex-Press miniature glaucoma implant is distributed by Optonol Schweiz AG, Bahnhofstrasse 7, PO Box 1142, CH-6301, Zug, Switzerland; (41) 41-7272270; fax: (41) 41-7272273; e-mail: optonol@optonol.com; Web site: www.optonol.com.