Microstent or Trabeculectomy: Comparing Efficacy, Safety, and Risk of Failure
Ophthalmology, November 2017
Implanted ab interno gelatin microstents are perceived as safer and less invasive than trabeculectomy for treating progressive glaucoma, but comparison studies are lacking. Schlenker et al. conducted a retrospective study of the standalone treatments (each done with mitomycin C) and noted similar safety profiles and failure rates.
For this study, the authors reviewed medical records to identify adults with glaucoma who underwent either procedure at 1 of 4 academic ophthalmology centers located in different countries. The primary outcome was hazard ratio (HR) of failure. Failure was defined as 2 consecutive readings of intraocular pressure (IOP; < 6 mm Hg with vision loss or > 17 mm Hg without medications, which they defined as “complete success”) at least 1 month after surgery despite in-clinic interventions. Secondary outcomes included IOP thresholds of 6-14 mm Hg and 6-21 mm Hg, and the same thresholds allowing for medications (defined as “qualified success”).
Of the patients identified, 159 (185 eyes) received a microstent and 139 (169 eyes) had trabeculectomy. Preoperatively, those scheduled for microstent had better visual acuity, were younger, and more often were male. Other baseline characteristics were comparable.
For the primary outcome threshold of 6-17 mm Hg, adjusted HRs of failure for microstent relative to trabeculectomy were 1.2 for complete success and 1.3 for qualified success. Times to 25% failure were 11.2 and 10.6 months for complete success and 30.3 and 33.3 months for qualified success, respectively. White race was linked to lower risk of failure (adjusted HR, 0.49; more pronounced with trabeculectomy), and diabetes was associated with higher failure risk (adjusted HR, 4.21).
Overall, microstent and trabeculectomy recipients underwent 114 and 165 postoperative interventions, respectively, and 43% and 31% underwent needling. Fifty percent of those with trabeculectomy had laser suture lysis. There were 22 complications with microstent and 30 with trabeculectomy. Most were transient.
Although these findings indicate similar rates of complete and qualified success, the authors urged clinicians to weigh the pitfalls of each procedure, including the potential for needling and reoperation with microstent and the greater likelihood of interventions and complications after trabeculectomy. (Also see related commentary by Dale K. Heuer, MD, in the same issue.)
The original article can be found here.