One of the puzzling aspects of glaucoma management is the longevity of its gold standard surgical solution, trabeculectomy. Few other medical specialties, not even mentioning ophthalmic subspecialties, can 'boast' of such an unflattering remedy, one with a safety profile und unpredictability that seem to stem from pre-modern medicine. Therefore, for any new glaucoma surgical technique to compare itself to trabeculectomy seems at once logical and brave nevertheless. Therefore, Sheybani and colleagues are to be congratulated for having conducted this RCT of the XEN gel stent to trabeculectomy.
Designing such a study confronts the investigators with many questions, each with their own limitations and pitfalls. The authors wisely chose a primary end point, which is a composite of efficacy and safety and should avoid biasing the study to either of the studied techniques: the proportion of patients at month 12 achieving ≥20% IOP reduction from baseline without increase in IOP-lowering medications, clinical hypotony, loss of vision to counting fingers, and/or secondary glaucoma surgical intervention. The authors found that at one year the XEN gel stent was statistically non-inferior to trabeculectomy with 62.1% vs. 68.2% achieving that endpoint. Notable findings favoring the XEN stent were (1) faster visual recovery; (2) greater six-month improvements in visual function problems; and (3) lower rates of office-based postoperative surgical procedures (34.7% vs. 63.6%), and lower rates of hypotony (23.2% vs. 50.0%). Favoring trabeculectomy was a statistically lower IOP, fewer medications, and fewer surgical failures.
This study's results, if replicated in other populations and other glaucoma types would place the XEN gel stent as a viable less-invasive alternative to trabeculectomy, especially when efficacy, safety, and patients' quality of life are weighted against each other
This well-designed study has few limitations, including a low representation of patients of African ethnicity (< 18% of the total) and with a diagnosis of pseudo-exfoliation glaucoma (< 4% of the total). It is also regrettable that measurements of endothelial cell density were not obtained, given that this newly important parameter could guide surgeons towards their decision.
This study's results, if replicated in other populations and other glaucoma types would place the XEN gel stent as a viable less-invasive alternative to trabeculectomy, especially when efficacy, safety, and patients' quality of life are weighted against each other.