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Large referral center explores efficacy of Trabectome-mediated ab interno trabeculectomy
Good results were seen in challenging eyes, which should justify proceeding with a formal comparative trial of this MIGS system.
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Eye surgeons who perform minimally invasive glaucoma surgeries, or MIGS, often wonder whether they buy reduced complications so common in traditional glaucoma surgeries at the cost of diminished IOP-lowering efficacy. This concern grew when first results of trabecular bypass micro stents seemed to indicate that the effect was only slightly better than that of cataract surgery alone.
These disappointing results led the procedure to being termed “minimally effective glaucoma surgery,” or MEGS, by Weinreb.
At UPMC, we reviewed our outcomes with a different MIGS modality, Trabectome-mediated ab interno trabeculectomy, which differs from micro stents by accessing more outflow tract segments and by not leaving hardware in the eye. We wanted to see whether results may justify proceeding with a randomized controlled trial to compare Trabectome (NeoMedix) with traditional glaucoma surgery.
Nils A. Loewen
An initial review showed that our patients who had Trabectome-mediated ab externo trabeculectomy had an average IOP of 14.5 mm Hg at 1 year, with minimal attrition at 2 years. Eighty-one percent of patients had an IOP below 18 mm Hg, 52% of patients had an IOP below 15 mm Hg, and 27% had an IOP below 12 mm Hg. Among our pseudoexfoliation glaucoma patients, 50% had an IOP of less than 12 mm Hg, rivaling published results of trabeculectomy.
Encouraged by this, we recently performed a more challenging comparison and put Trabectome surgery at a distinct disadvantage: We assessed outcomes of Trabectome after trabeculectomy; Trabectome vs. tube shunts in similar patient populations; and Trabectome in highly complex, advanced mixed-mechanism glaucomas.
Outcomes
First, in our “Trabectome after Trab” study, we found that Trabectome worked surprisingly well in patients who had failed trabeculectomy, lowering IOP by 28% from 23.7 ± 5.5 mm Hg and medications from 2.8 ± 1.2 to 2 ± 1.3 in 58 patients. In phaco-Trabectome, the mean IOP decreased 19% from 20 ± 5.9 mm Hg and medications from 2.5 ± 1.5 to 1.6 ± 1.4 in 15 patients. It was previously thought that once an outflow tract is bypassed by traditional filtering surgery, it atrophies and becomes useless. This is apparently not the case, and this group of patients can benefit from the benign, hands-off postoperative course Trabectome surgery affords.
Second, when we compared in our “Trabectome vs. Tube” study 1-year outcomes of Trabectome in 125 patients with Baerveldt glaucoma implant (Abbott Medical Optics) in 162 patients and Ahmed glaucoma valve (New World Medical) in 44 patients, in our patients with relatively similar disease stages we were surprised to see that postoperative IOPs and reduction of medications to achieve those were not significantly different. Trabectome patients had a final IOP of 14.9 ± 3.9 mm Hg and medications were reduced by 0.9; Baerveldt patients had a final IOP of 14.5 ± 4.9 mm Hg and medications were reduced by 0.9; and Ahmed patients had a final IOP of 16.7 ± 6.2 mm Hg and medications were reduced by 0.5. As the most striking difference, the rate of complications was about 10 times less in Trabectome patients.
Third, in the analysis of “Trabectome in Complex High-Risk Glaucomas,” we found that of 15 eyes with advanced glaucomas after open globe trauma, retinal detachment and buckles, neovascular glaucomas or uveitis with secondary angle closure (or a combination of those), eyes with traumatic glaucoma experienced a reduction in IOP from 32 ± 9 mm Hg to 14 ± 4 mm Hg and in medication from 4 to 0; eyes with retinal detachments experienced a reduction in IOP from 31 ± 10 mm Hg to 15 ± 4 mm Hg and in medication from 4.4 to 1; eyes with neovascular glaucomas experienced a reduction in IOP from 46 ± 12 mm Hg to 15 ± 8 mm Hg and in medication from 3.3 to 1; and eyes with uveitic glaucomas experienced a reduction in IOP from 30 ± 6 mm Hg to 12 ± 5 mm Hg and in medication from 3.7 to 1.3.
Advances in glaucoma surgery
One has to keep in mind that the studies above were not randomized controlled trials and do not allow a direct comparison. However, these results indicate that one can achieve surprisingly good results with a minimally invasive glaucoma surgery not just in mild glaucomas but even in the most challenging eyes. This should justify proceeding with a formal trial.
At UPMC, we like to compare advances in glaucoma surgery to that in cardiac surgery and interventional cardiology: Similar to how open heart surgery compares with angiographic stenting, there will always be a place for tube shunts and trabeculectomy while MIGS will increase. We believe that, in analogy to angiography, glaucoma surgeons will become better at assessing the outflow tract before surgery to make an informed decision what surgery to use. Eventually, Trabectome-mediated ab interno trabeculectomy and similar MIGS may do what phacoemulsification did to extracapsular cataract incision, allowing earlier, safer intervention that is also very effective.
Visit UPMCPhysicianResources.com/Ocular to learn more about the use of MIGS. You can also submit clinical questions or read the most recent questions asked of the UPMC Eye Center’s ophthalmology experts.