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Preliminary results encouraging for gonioscopy-assisted transluminal trabeculotomy
A retrospective case series finds the minimally invasive technique is comparable in efficacy and safety to ab externo trabeculotomy.
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The efficacy and safety of minimally invasive gonioscopy-assisted transluminal trabeculotomy for treating open-angle glaucoma are at least equivalent to published results for ab externo trabeculotomy, according to a study.
“We can now perform a 360° trabeculotomy without having to touch the conjunctiva and without having to make any conjunctival or scleral incisions,” lead investigator Davinder S. Grover, MD, MPH, said.
Anyone with open-angle glaucoma is a candidate for gonioscopy-assisted transluminal trabeculotomy (GATT), as are most patients with mild or moderate glaucoma, those with congenital or developmental glaucoma, and any person with angle dysgenesis, although the patient must have an intact collector system, Grover told Ocular Surgery News.
Grover co-developed GATT with colleagues Ronald Fellman, MD, David Godfrey, MD, and Tosin Smith, MD, from Glaucoma Associates of Texas.
Technique
GATT entails making two corneal paracenteses to perform a goniotomy and then cannulating Schlemm’s canal with a microcatheter or suture within the eye. The catheter or suture is passed 360° around the canal, retrieved and externalized, thereby creating a 360° circumferential trabeculotomy.
In a retrospective chart review published in Ophthalmology, the procedure was performed in 85 patients; 57 had primary open-angle glaucoma and 28 had secondary open-angle glaucoma. All patients were followed for at least 6 months.
In the primary glaucoma group, there was a mean decrease in IOP of 7.7 mm Hg at 6 months and 11.1 mm Hg at 12 months, plus a decrease of 0.9 glaucoma medications at 6 months and 1.1 glaucoma medications at 12 months.
In the secondary glaucoma group, IOP decreased by 17.2 mm Hg at 6 months and 19.9 mm Hg at 12 months, whereas the number of glaucoma medications was reduced by 2.2 at 6 months and 1.9 at 12 months.
“These results are in line with or better than published studies of ab externo circumferential trabeculotomy,” Grover said. “This is not surprising because GATT is a less traumatic and less invasive way of performing the same procedure.”
Moreover, because the conjunctiva is not violated during GATT, the technique does not preclude the eye from having a subsequent surgery and diminishing those subsequent success rates, he said.
Grover said that the secondary glaucoma group fared better with GATT because the surgery essentially removes the trabecular meshwork.
“In secondary glaucoma patients, the pathology is usually in the trabecular meshwork, so if you can remove the pathology, the surgery has a tendency to work better, such as in patients with pseudoexfoliation,” he said.
The most common complication among the two combined groups was transient hyphema, which was observed in 30% of patients at the 1-week visit.
Grover said GATT is easier to learn using a microcatheter rather than a suture because the distal tip of the catheter is illuminated for enhanced visualization of Schlemm’s canal.
Future reports
The authors are preparing longer 1- to 2-year follow-up data of the same patient cohort.
“Patients have prolonged IOP control, which is consistent with previous published results on long-term externo trabeculotomies,” Grover said.
The authors are also readying for publication the outcomes of GATT in pediatric and developmental glaucoma cohorts. “All the eyes did extremely well,” Grover said.
Results of eyes that have been treated with GATT following either previously failed trabeculectomy or tubes are also being prepared for publication.
“The outcomes are surprisingly good, considering the refractory nature of this population,” Grover said. – by Bob Kronemyer
Reference:
Grover DS, et al. Ophthalmology. 2014;doi:10.1016/j.ophtha.2013.11.001.
For more information:
Davinder S. Grover, MD, MPH, is an attending surgeon and clinician at Glaucoma Associates of Texas and can be reached at 10740 N. Central Expressway, Suite 300, Dallas, TX 75231; 214-360-0000; email: dgrover@glaucomaassociates.com.
Disclosure: Grover has no relevant financial disclosures.