By Lorraine (Lori) Provencher, MD
Every surgeon performs traditional glaucoma surgery a little differently. Techniques vary widely, supporting the notion that there is no
right way or wrong way to perform a trabeculectomy or a tube shunt surgery. There is, however, a method that works best for each surgeon, and nuanced, variable techniques are developed over time based on our training, our experiences, our network, and new data.
Minimally invasive glaucoma surgeries (MIGS) are not as variable, probably because they involve less manipulation of ocular tissue, are generally less complex, and have not been in use as long. An exception is the XEN Gel Stent (Allergan), a procedure that borders on MIGS by accessing the subconjunctival space like more traditional incisional glaucoma surgery. XEN was originally approved as an ab interno procedure, but techniques evolved to include ab externo (“ab-ex”) placement as well.
As a result of this evolution that takes place in the operating room, we can find the technique that works best in terms of surgeon skill set and patient outcomes.
We can see this evolution in action with ab externo XEN implantation with both open conjunctival and trans-conjunctival approaches. I learned the ab interno approach in fellowship, but I learned ab externo with open conjunctiva on my own by talking to colleagues, watching videos, and observing another surgeon. If you have experience with trabs and tubes, it’s very intuitive to do ab externo open conjunctiva XEN, which draws on analogous concepts. Ab externo placement is now my preferred technique. Here’s what I’ve learned as I transitioned from ab interno to ab externo:
One of the most rewarding aspects of surgery is the ability to innovate and constantly improve upon existing techniques, and I’ve found that glaucoma specialists are happy to have multiple options when it comes to XEN implantation. Ophthalmologists that do not perform trabs and tubes may be less comfortable working with the conjunctiva and less likely to adopt an ab externo technique. Nevertheless, they can still feel confident that they will achieve great results with ab interno implantation. No matter the method, XEN surgeons should strive to determine the technique that works best in their hands.
Lorraine (Lori) Provencher, MD, is a glaucoma specialist at the Cincinnati Eye Institute.
Disclosure: Dr Provencher reports she is a speaker and consultant for Allergan; and a speaker for MST.