Illuminated microcatheter aids successful trabeculotomy
Limited case series of cannula device shows promise in full 360° pediatric glaucoma surgery.
A microcatheter with an illuminated tip allowed improved visualization of 360° trabeculotomy in pediatric glaucoma cases, lowering IOP in a group of patients, a study found.
Peter W. DeBry
The study, the first U.S. series of the iTrack microcatheter (iScience Interventional) in such cases, examined use of the device in 12 eyes of eight children who underwent 360° trabeculotomy.
Peter W. DeBry, MD, and colleagues conducted a chart review with 6.6 months follow-up, examining surgical success rate, surgical complications, preoperative and postoperative IOP, and any further surgery needed.
They found that average preop IOP of patients was 31 mm Hg and average postop IOP was 17 mm Hg. Dr. DeBry said the pressure-lowering effect of the microcatheter was difficult to fully assess because of the small case set in the study, but the device showed promise in the pediatric cases.
“This microcatheter appears to be a useful tool for trabeculotomy,” he said.
The device, designed to cannulate into Schlemm’s canal, has a 250 µm outer diameter, a wire to stiffen the material and a hollow bore for viscoelastic. Although all of its features appear to contribute to successful pediatric trabeculotomy, the device’s key benefit is a fiber optic light source that illuminates the end of the catheter tip, Dr. DeBry said.
The light source and smooth tip with viscoelastic help achieve the main goal in 360° trabeculotomy cases for congenital glaucoma: passing the suture, circumferentially, around the canal 360°, he said.
“For those of you who have done a 360° trabeculotomy with a suture, sometimes the suture keeps going and going, and you don’t really know where the end of that suture is,” Dr. DeBry said. “So in this case, you have a laser light source to help identify the tip of the catheter.”
By illuminating the catheter tip, surgeons can more easily determine the location of the suture and achieve full 360° surgery more often.
“One nice thing about this is if the catheter doesn’t go 360°, we’re able to identify the tip of the catheter and make a cut down to retrieve the tip and treat at least some of the angle,” he said.
Another benefit of the microcatheter is its atraumatic, smooth tip, Dr. DeBry said. The injection of viscoelastic as the microcatheter is advanced provides lubrication for the tip.
How it works
Dr. DeBry said the trabeculotomy procedure using the iTrack microcatheter does not differ from traditional trabeculotomy, other than using a more sophisticated device for tearing through the inner wall of Schlemm’s canal. The iTrack procedure starts with two flaps and deroofing of Schlemm’s canal. After creating those incisions, cannulation at Schlemm’s canal occurs and viscoelastic fills the anterior chamber.
After the two ends of the microcatheter are pulled around Schlemm’s canal, a “gentle tangential tension” is applied to both ends, so that it pulls through the trabecular meshwork, he said.
The flaps are sutured securely after completion of the procedure.
In contrast, traditional goniotomy typically has a single clear corneal incision, allowing treatment of 120° to 180° of the angle, Dr. DeBry and colleagues said in a poster of the study.
Prolene suture trabeculotomy allows a higher degree of angle to be treated, up to 360°, through a single incision but often poses problems when the suture cannot be passed through the canal, Dr. DeBry and colleagues said.
“It is not uncommon that in a standard trabeculotomy, the suture cannot be passed the full 360°, necessitating access through a second site to achieve this result,” they said.
Patients’ success rate
Even though the iTrack microcatheter study set was small and had a limited follow-up of 6.6 months, results for trabeculotomy using the device appear promising, Dr. DeBry said at the American Society of Cataract and Refractive Surgery meeting in Chicago, noting that 75% of patients, or eight of the 12 in the study, achieved 360° of treatment.
However, three eyes did not achieve full 360° success, he said. Those cases achieved at least 200° when surgeons made a small incision at the cannula tip. One eye also had a poorly developed angle with no identifiable Schlemm’s canal.
In addition, two eyes needed further surgery with a glaucoma implant because of uncontrolled pressure, Dr. DeBry said. One eye, which had severe Peter’s anomaly preoperatively, had an Ahmed valve implanted. The other eye, which had moderate to severe congenital cataract, also had a tube implanted.
For more information:
- Peter W. DeBry, MD, can be reached at Wellish Vision Institute, 2110 E. Flamingo Road, Suite 101, Las Vegas, NV 89119; 702-733-2020; fax: 702-734-1770; e-mail: firstname.lastname@example.org. Dr. DeBry has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.
- iScience Interventional, maker of the iTrack microcatheter, can be reached at 4055 Campbell Ave., Menlo Park, CA 94025; 888-846-4724; fax: 650-421-2700; e-mail: email@example.com; Web site: www.iscienceinterventional.com.
- Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.