Miniature drainage implant shows promising results for combined filtration, cataract

IOP and number of glaucoma medications used by patients decreased after surgery.

ByMichael Piechocki

In a small, noncomparative case series conducted in Genoa, Italy, the Ex-Press Miniature Glaucoma Implant was safe and effective for control of IOP for up to 2 years in combined procedures.

Prof. Carlo E. Traverso, a glaucoma specialist at the University of Genoa, prospectively evaluated the efficacy of the implant, manufactured by Optonol Ltd., in combined cataract and glaucoma filtration procedures.

He presented results at a meeting held earlier this year.

He said the follow-up data supports the efficacy and safety of the implant for combined surgery in patients with primary open-angle glaucoma and cataract. However, more data is needed before final conclusions can be made, he said.

“We need to be evidence-based and fair and perhaps compare new techniques using the same standards used in publications for evaluating other glaucoma surgeries in the past,” Prof. Traverso said. “I think we are not happy, at least I am not so, with trabeculectomy in combined procedures unless antimetabolites and aggressive bleb management are employed. There is room for improvement.”

Implantation

The Ex-Press Miniature Glaucoma Implant is implanted at the limbus through a conjunctival incision.

Ten consecutive white patients were included in the study. Follow-up ranged from 9 weeks to 104 weeks, with a mean of 88.7 ± 30.5 weeks. One patient was lost to follow-up at 9 weeks.

In all cases, phacoemulsification was performed via a temporal clear corneal incision. Using a specially designed introducer, the Ex-Press Miniature Glaucoma Implant was implanted at the limbus through a conjunctival incision. No antimetabolites were used during implantation.

Outcome measures included control of IOP, decrease in use of glaucoma medications and evaluation of complications.

Prof. Traverso said the Ex-Press implant should not be compared to other implants for complicated or high-risk glaucomas, where the goal is not creation of a filtering bleb at the limbus. Instead, this device is to be considered as an alternative to trabeculectomy or nonpenetrating filtration surgery, since a conjunctival filtration bleb is created, he said.

Prof. Traverso noted implantation of the device is relatively straightforward, with correct positioning of the implant the most crucial consideration for preventing complications. The implant is placed under the conjunctiva and positioned at the limbus.

“Technically speaking, it is a simple procedure for trained microsurgeons. But it does require exact, precise, perfect positioning,” he said.

Results

According to the study, the average IOP decreased from 26.6 ± 6 mm Hg preoperatively to 15.8 ± 4.4 mm Hg at 52 weeks (n=9) and 15.3 ± 3.6 mm Hg at 104 weeks (n=7).

The average number of medications used by patients also decreased after surgery. Preoperatively, patients in the study used an average of 3.4 ± 0.8 medications. This was lowered to 0.1 ± 0.3 medications postoperatively at 52 weeks follow-up, and 0.3 ± 0.5 medications at 104 weeks.

Only one patient required use of medications to control IOP at 52 weeks, and two patients at 104 weeks.

Chart
The Ex-Press is a glaucoma implant for the treatment of open-angle glaucoma. The minimally invasive implant, less than 3 mm long, 400 µm in diameter, is effective in lowering IOP. It diverts the aqueous humor from the anterior chamber to the subconjunctival space to form a filtration bleb.

Source: www.optonol.com.

Prof. Traverso said that the long- lasting IOP lowering is also related to the intensive postoperative bleb management he routinely uses in all filtration surgeries, since he considers it preferable to manipulate the bleb rather than restarting IOP-lowering medications.

Regarding safety, Prof. Traverso said one implant rotated at 2 months postop and was repositioned. The plate that is normally flush with the sclera had turned to the side. The patient may have had a thinner than average sclera at the limbus, but did not have previous surgery and was not highly myopic.

“When the implant is rotated, the risk of erosion is greater, so I elected to reposition the implant rather than wait for erosion,” he said.

One device also came in contact with the iris at 3 months postop, but this did not cause any clinical adverse consequences. Four cases of Tenon’s cysts were seen. Postoperative bleb intervention with antimetabolites was necessary in five eyes (50% of patients) and without antimetabolites in one eye.

Prof. Traverso said no complications related to phacoemulsification were experienced. There were also no cases of flat anterior chamber, choroidal detachment, iris traction or long-term hypotony.

Success criteria

All patients except two with severe macular degeneration had an improvement in visual acuity.

“If you look at 2-year follow-up, an IOP of 21 mm Hg or lower, with or without IOP-lowering medications, was achieved in 90% of the cases, while a level of 18 or 15 mm Hg was obtained at maximum follow-up in 80% and 50% of the cases, respectively,” he said.

Referring to Kaplan-Meier survival curves, at 2-year follow-up there was a 75% likelihood of having an IOP up to 18 mm Hg. However, no patients needed repeat glaucoma surgery.

For Your Information:

Prof. Carlo E. Traverso can be reached at Clinic Oculistica, Di.N.O.G. Universita di Genova, Ospedale San Martino 16132 Genova Italy; +(39) 010-353-8452; e-mail: mc8620@mclink.it.

Optonol Schweiz AG, makers of the Ex-Press Minature Glaucoma Implant, can be reached at Bahnhofstrasse 7, PO Box 1142, CH-6301, Zug, Switzerland; +(41) 41-727-2270; fax: +(41) 41-727-2273; Web site: www.optonol.com.