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Marked suture aids gonioscopy-assisted transluminal trabeculotomy
A marked blunted suture can be visualized almost as well as a microcatheter and is more cost-effective.
Gonioscopy-assisted transluminal trabeculotomy performed with a thermally marked suture is a safe alternative to the same procedure with an illuminated microcatheter, according to a study.
The modified gonioscopy-assisted transluminal trabeculotomy (GATT) technique allows for visualization comparable to that of the original method.
GATT, a novel technique for performing an ab interno circumferential trabeculotomy, is safer and less invasive than traditional methods, according to corresponding author Davinder S. Grover, MD, MPH.
“You really have a 70% to 80% chance of success of lowering the pressure to a very safe range without doing anything major to the eye,” Grover told Ocular Surgery News. “The advantage of GATT is that it can safely and effectively open up the patient’s own drainage system without making a major incision on the eye or doing any traditional glaucoma surgeries.”
In addition, GATT avoids many side effects associated with conventional glaucoma surgery, Grover said.
The study was published in the Journal of Glaucoma.
Basic technique
A 4-0 or 5-0 clear nylon suture is cut to a sufficient length to pass around Schlemm’s canal. An ophthalmic surgical marking pen is used to mark the tip of the suture, and then a heating source is used to blunt the tip. The ink is melted into the blunted tip of the catheter.
After standard sterilization measures, the eye is draped and an open wire nasal lid speculum is inserted to keep the eyelids open. A 23-gauge needle paracentesis track is placed in the superonasal or inferonasal quadrant.
Viscoelastic is injected into the anterior chamber, and a temporal paracentesis is created. A 4-0 or 5-0 nylon suture with a blunted tip is inserted into the anterior chamber through the entry site, with the tip resting in the nasal angle.
The patient’s head and the microscope are positioned to allow adequate visualization of the nasal angle with a goniolens.
A microsurgical blade is used to create a 1- to 2-mm goniotomy. Microsurgical forceps are inserted through the temporal site and used to grasp the marked suture within the anterior chamber.
The distal tip of the suture is inserted into Schlemm’s canal at the goniotomy incision. Once inside the anterior chamber, the microsurgical forceps are used to insert the suture counterclockwise through the circumference of the canal.
A gonioprism can be used to visualize the progress of the suture.
A bimanual irrigation and aspiration system is used to remove the viscoelastic from the anterior chamber. The anterior chamber can be filled 25% with viscoelastic to help tamponade bleeding from the canal.
Postoperatively, subconjunctival or intracameral corticosteroid drops are given.
Suture vs. microcatheter
The microcatheter used in GATT can cost up to $800, Grover said.
“It’s expensive, but the catheter is beneficial because it’s great for teaching and it’s great for learning because you can see the suture go around 360°. I think it really helps one learn the technique, and it helps people get a handle on how to do the surgery. I think it’s just an easier way to teach people,” Grover said.
Experience with a catheter can prepare surgeons to use a suture, he said.
“Once you get the hang of it and you know how to do the surgery and you feel comfortable with doing the surgery, then the exciting thing about it is that you can use the suture, which is a $4 technique,” Grover said. “Once people get comfortable with the catheter and get over some of the learning curve components of how you need to move things and how you have to manipulate the eye, the suture can be done just as easily and just as safely.”
A marked suture can be visualized nearly as well as an illuminated microcatheter, Grover said.
“When you mark the suture and then blunt it and then you look on gonioscopy, it’s easier to find than if you didn’t mark it,” he said. “It still allows you to see where you are in the angle if you get held up or you need to find out where you are. The marked tip allows you to see that.”
Additionally, GATT is significantly more cost-effective with a suture than with a microcatheter, Grover said.
“It has tremendous implications in the United States for delivering cost-effective health care. But the exciting thing in my mind is that when you think about providing glaucoma surgical care in developing countries, this has a great potential to treat glaucoma safely and successfully without the long-term follow-up that traditional trabeculectomy or a tube would need,” he said. – by Matt Hasson
- Reference:
- Grover DS, et al. J Glaucoma. 2015;doi:10.1097/IJG.0000000000000325.
- For more information:
- Davinder S. Grover, MD, MPH, can be reached at Glaucoma Associates of Texas, 10740 N. Central Expressway, Suite 300, Dallas, TX 75231; email: dgrover@glaucomaassociates.com.
Disclosure: Grover reports no relevant financial disclosures.