Outcomes of post-trabeculectomy Xen45 gel stent comparable to primary implantation
Click Here to Manage Email Alerts
The Xen45 gel stent is a viable option after failed trabeculectomy and has the same good results as primary implantation in terms of IOP-lowering effect and independence from glaucoma medications, according to a study.
When trabeculectomy fails, a second attempt with the same procedure leads to poorer outcomes, and often glaucoma drainage devices have been used. The Xen45 gel stent (Allergan) is a latest-generation drainage device with a smaller lumen, requiring a less invasive ab interno implantation technique. The use of Xen after failed trabeculectomy is not new, but no studies had so far compared the results of it as a secondary vs. primary procedure.
By reviewing a database of patients who underwent Xen45 gel stent implantation, a group of 30 eyes of 30 pseudophakic patients with previous failed trabeculectomy were identified and matched with a control group of 60 eyes of 60 patients who had undergone Xen45 gel stent implantation as a primary procedure.
The stent was implanted in the upper nasal quadrant after injecting 0.1 mL mitomycin C under the conjunctiva. The apex of the injector was pushed through the trabecular meshwork and sclera to make the stent reach the anterior chamber, previously filled with viscoelastic. After checking the correct positioning of the device by gonioscopy, the viscoelastic was removed, and the proximal end of the Xen was secured under the conjunctiva.
In cases of insufficient IOP-lowering effect, open conjunctival revision was performed, removing the scar tissue from the stent. Revision rate was 30%.
“We always perform open conjunctival revision because we do not believe that needling can lower the IOP to the extent needed to diminish the need for supportive therapy,” the authors wrote. In addition, open revision surgery gives the chance to inspect the stent and exchange it if it is damaged. “By performing needling, this would have been overlooked,” they said.
Over a mean follow-up period of 20 months, all 90 patients achieved a 42% mean IOP reduction, from 24.4 mm Hg to 14.1 mm Hg. Medication use was reduced by 89%, from 2.7 to 0.3. Outcomes in the two groups were comparable in terms of IOP, medication score, revision rate and success rate.
The retrospective nature, limited number of patients and relatively short follow-up are limitations of this study. However, the authors wrote that large numbers would not be “a realistic option for a study with Xen45 gel stent implantation after trabeculectomy.”
They recommended Xen45 gel stent as an option after failed trabeculectomy.
“According to our results, there is no disadvantage compared with initial Xen45 gel stent implantation,” they wrote.
Perspective
Back to Top
Xen45 gel stent implantation in the superior nasal quadrant is a viable option after failed trabeculectomy, according to the results described in this paper. The procedure is safe and has no disadvantage compared with primary Xen45 gel stent implantation.
This paper suggests that the Xen45 gel stent can be a bridge between a failed trabeculectomy and the need to pursue a more aggressive course of either a repeat trabeculectomy or a larger glaucoma drainage tube.
A longer follow-up is required to assess whether this option maintains a significant IOP-lowering effect in the long term, stabilizing the glaucomatous damage.
Perspective
Back to Top
This study addresses a major concern of glaucoma filtration surgery, which is the low success rates of a second trabeculectomy performed when the first has failed, as shown by many papers published in the literature. The authors compared two groups of patients, those who had a trabeculectomy first and then went on to Xen surgery, and those in which Xen surgery was performed as a primary procedure. MIGS stents are typically used in combination with cataract surgery, and this combination partly accounts for their success. Xen is an exception, as it has shown to work equally well whether it is or it is not combined with cataract surgery. However, because many eyes that undergo trabeculectomy have already undergone cataract extraction, to keep the groups more homogenous, all selected eyes were pseudophakic.
The authors found two things that are important. No. 1, there is no difference between how well Xen works in an eye that had a trabeculectomy that failed than in an eye that never had trabeculectomy. This is quite remarkable, and it suggests that Xen is versatile. A reason why it is successful also as a secondary surgery is that Xen is placed in the superonasal quadrant, which is relatively apart from the area that is affected by primary trabeculectomy.
No. 2, the authors were able to show that Xen has good efficacy. Mean IOP reduction was 42%, down from 24.4 mm Hg to 14.1 mm Hg. They also showed significant medication reduction, an impressive decrease from 2.7 medications at baseline to 0.3, which means that most patients were off drugs and only one out of three took one drop. They also showed good long-term efficacy, with more than half of the patients who did not have to repeat surgery over 2, 3 or, in some cases, 4 years. One-year success rate was above 80%.
This study adds to the current literature that shows that Xen can work in a variety of situations, independent of what other procedures come along with it. I may add my own experience, which I have recently published in a paper that shows that Xen can be effective whether is done with an ab interno or ab externo approach, with no major difference in success rate between these two groups. Xen is versatile and can work in different situations, alone or in combination with other surgeries, with different techniques, different patient populations and different types of eyes. Good news for glaucoma surgeons and patients.
Collapse
Click Here to Manage Email Alerts