Microstent on par with trabeculectomy for uncontrolled glaucoma
The risk of failure and safety profiles are comparable between standalone ab interno microstent with mitomycin C (MMC) and trabeculectomy with MMC, a recent study has found.
Researchers conducted a multicentre, retrospective interventional cohort study including 354 eyes of 293 patients with no prior incisional surgery. Consecutive eyes with uncontrolled glaucoma underwent microstent (n=185) or trabeculectomy (n=169) surgery from 1 January 2011 through 31 July 2015 at four academic ophthalmology centres in Canada, Germany, Austria and Belgium.
Hazard ratio (HR) of failure was the primary outcome measure. Failure was defined as two consecutive intraocular pressure (IOP) readings <6 mm Hg with vision loss >17 mm Hg without glaucoma medications (complete success) at least 1 month after surgery despite in-clinic interventions. Secondary outcome measures were IOP thresholds of 6 to 14 mm Hg and 6 to 21 mm Hg, and same thresholds allowing for medications (qualified success), interventions, complications and reoperations.
Baseline characteristics were similar, except that the microstent group had more men (56 vs 43 percent), younger patients (average, by 3 years), better preoperative visual acuity (22. Vs 32 percent with 0.4 logarithm of the minimum angle of resolution vision or worse) and more trabeculoplasty (52 vs 30 percent).
The adjusted HR of failure of the microstent vs trabeculectomy was 1.2 (95 percent CI, 0.7 to 2.0) for complete success and 1.3 (0.6 to 2.8) for qualified success, and similar for other outcomes. For complete success, time to 25-percent failure was 11.2 (6.9 to 16.1 months) and 10.6 months (6.8 to 16.2 months), and 30.3 (19.0 to ∞ months) and 33.3 months (25.7 to 46.2 months) for qualified success.
In general, an association existed between white ethnicity and decreased risk of failure (adjusted HR, 0.49; 0.25 to 0.96), and between diabetes and increased risk of failure (adjusted HR, 4.21; 2.10 to 8.45).
There were 117 and 165 interventions: 43 and 31 percent underwent needling, respectively, and 50 percent of trabeculectomy eyes underwent laser suture lysis. A total of 22 and 30 distinct complications were reported, but most were transient. Finally, 10 and 5 percent underwent reoperation (p=0.11).