Having explored the various options available for micro-invasive glaucoma surgery (MIGS), I now use several devices with success. One MIGS device (XEN Gel Stent, Allergan) differs from the others in that it drains aqueous into the subconjunctival space and can be performed as a stand-alone procedure without cataract surgery or combined with cataract surgery.
Because the glaucoma treatment is a relatively safe procedure with the potential to remove patients from medications or use fewer drops,1,2 it can meet many needs of my glaucoma patients, including control of IOP, reduction or elimination of compliance issues, lowering of prescription costs, a healthier ocular surface, and a better quality of life.
My initial experiences using the gel stent procedure took place outside the United States, and then I became involved in both phases of its FDA trial. I trained with both Allergan and its affiliate, AqueSys, whose practice labs have model eyes and injectors that let physicians learn the feel of the injector and the proper location of the stent. I used various injector types and both the 140-μm and 45-μm inner lumen versions—the latter of which is now approved by the FDA.
In the past 5 years, I have placed about 150 implants, including about 75 since its FDA approval. The glaucoma treatment system is without question the safest, least invasive, most effective, and most predictable glaucoma procedure for creating a new drainage system.3-5
It has substantially decreased the number of trabeculectomies and tube shunts that I perform.
I choose the gel stent procedure for patients with advanced open-angle glaucoma when there is suspicion that the inherent drainage system (collector channels) is no longer functional. I also perform it on patients who have failed angle-based surgery, such as gonioscopy-assisted transluminal trabeculotomy (GATT) or surgery with a dual blade (Kahook Dual Blade, New World Medical).
If a patient is very active or taking blood thinners, I may move to the gel stent procedure instead of angle-based surgery given the risk of hyphema in the immediate postoperative period.
The procedure is not an easy surgery (but then again, neither is cataract surgery), and it cannot be mastered after one case. It has a lot of subtleties in terms of comfort with the injector and anatomy of the orbit, angle, and conjunctiva. I felt somewhat comfortable placing the stent after about 5 cases, and I would say I felt very comfortable after 10 to 15 cases.
Comparing this with my first 50 cataract surgeries, it is clear that while it takes a few cases to feel comfortable with the gel stent procedure, it is easy to learn and can be performed by most surgeons with proper knowledge and training.
The best advice I can offer is to practice using the injector before going to the operating room. Take an injector home, practice using it with the dominant and non-dominant hand, and hold the injector in various positions until the best position is found. Practice with the injector 10 to 15 times in the practice lab, keeping in mind that the ideal surgical placement is in the subconjunctival space (anterior to Tenon’s capsule).