Compare efficacy and safety of early compared to later surgical cases in patients receiving an ab-interno gelatin microstent with mitomycin C (MMC).
Canada-wide, multicenter, retrospective propensity score matched cohort study.
Two hundred and seventy eyes (135 early cases and 135 later cases group) with no prior incisional surgery.
Surgeons’ first 20 cases (early cases group), from 6 glaucoma surgeons across 4 Canadian sites, were matched 1:1 to cases with the closest propensity score from the later (21+) cases (later cases group). Cases conducted by fellows were included as additional separate surgeons.
Primary outcome was hazard ratio of failure of early versus later cases, with failure defined as IOP 2 lines of vision loss, or >17 mmHg on no medications (complete success) on 2 consecutive visits despite in-clinic maneuvers (including needling) >1 month post-operatively. Secondary outcomes were HRs for failure defined as IOP outside the range of 6-14 and 6-21 mmHg with and without allowing for medications (qualified success), interventions, complications, and reoperations.
HR of failure for early versus later cases for the IOP range of 6-17 mmHg was 1.38(0.97-1.96), 1.29(0.90-1.84) for 6-14 mmHg, and 1.48(1.03-2.13) for 6-21 mmHg without medication and 0.95(0.55-1.64), 0.95(0.61-1.48), 0.95(0.52-1.75) for the same IOP ranges allowing for medications. Complete success rates for IOP 6-17 mmHg at 1 year were 42%(SE 5%) for early cases and 51%(SE 5%) for later cases and qualified success were 82%(SE 4%) and 76%(SE 4%) respectively. Needling rates were 43.0% (early cases) and 41.5% (later cases). Complication rates after 1 month occurred in 9.6% (early cases), and 11.1% (later cases) (p=0.69). Reoperation rates were 14.8% (early cases) and 8.1% (later cases) (p=0.08).
There is some evidence for improved complete success in later cases, no evidence for difference in success for qualified success, similar needling rates, similar complication rates, and a slightly higher reoperation rate in early cases. The results suggest that this procedure can be adopted by existing surgeons with current training regimens, though they may see an improvement in their success outcomes over time.

Copyright © 2021. Published by Elsevier Inc.