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Surgeon Experience as a Risk Factor for Short-Term Failure for Ab Interno Gelatin Microstent: A Canadian Multicenter
Matthew B Schlenker1, Jeb Alden Ong1, Pearson Wu1
1Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada; Prism Eye Institute, Mississauga, Canada.
Purpose:
To compare the efficacy and safety of early versus later ab interno gelatin microstent placement with mitomycin C.
Design:
Canada-wide, multicenter, retrospective propensity score-matched cohort study.
Participants:
Two hundred seventy eyes (135 early cases and 135 later cases) with no prior incisional surgery.
Methods:
Surgeons' first 20 patients (early cases group), from 6 glaucoma surgeons across 4 Canadian sites, were matched 1:1 to patients with the closest propensity score from the later (21+) patients (later cases group).
Main Outcome Measures:
Primary outcome was hazard ratio (HR) of failure of the early versus later cases groups, with failure defined as IOP of less than 6 mmHg with more than 2 lines of vision loss or more than 17 mmHg with no medications (complete success) on 2 consecutive visits despite in-clinic maneuvers (including needling) more than 1 month after surgery. Secondary outcomes were HRs for failure, defined as IOP outside the range of 6 to 14 mmHg and 6 to 21 mmHg with and without allowing for medications (qualified success), interventions, complications, and reoperations.
Results:
Hazard ratio of failure for early versus later cases groups was 1.38 (95% confidence interval [CI], 0.97-1.96) for the IOP range of 6 to 17 mmHg, 1.29 (95% CI, 0.90-1.84) for 6 to 14 mmHg, and 1.48 (95% CI, 1.03-2.13) for 6 to 21 mmHg without medication and 0.95 (95% CI, 0.55-1.64), 0.95 (95% CI, 0.61-1.48), and 0.95 (95% CI, 0.52-1.75) for the same IOP ranges allowing for medications. Needling rates were 43.0% (early cases group) and 41.5% (later cases group). Complication rates after 1 month occurred in 9.6% (early cases group) and 11.1% (later cases group; P = 0.69). Reoperation rates were 14.8% (early cases group) and 8.1% (later cases group; P = 0.08).
Conclusions:
There is some evidence for improved success in the later cases group. Similar needling rates, similar complication rates, and a slightly higher reoperation rate were found for the early cases group. The results suggest that this procedure can be adopted by existing surgeons with current training regimens, although they may see an improvement in their success outcomes over time.
Insights
Early ab interno gelatin microstent placement showed slightly higher reoperation rates and no significant difference in complications compared to later placement. Success outcomes may improve with surgeon experience.
Area of Science:
- Ophthalmology
- Glaucoma Surgery
- Medical Devices
Background:
- Ab interno gelatin microstent implantation is a surgical option for glaucoma management.
- Understanding the learning curve for new surgical techniques is crucial for optimizing patient outcomes.
Purpose of the Study:
- To compare the efficacy and safety of early versus later ab interno gelatin microstent placement with mitomycin C.
Main Methods:
- Retrospective, propensity score-matched cohort study involving 270 eyes from 6 surgeons across 4 Canadian sites.
- Early cases (first 20 patients per surgeon) were matched 1:1 with later cases (21+ patients).
- Outcomes assessed included intraocular pressure (IOP) control, needling, complications, and reoperations.
Main Results:
- Hazard ratios for failure (IOP > 17 mmHg without medication) were 1.38 (6-17 mmHg) and 1.48 (6-21 mmHg) for early versus later cases, suggesting potentially lower success in early cases.
- Needling rates (43.0% vs 41.5%) and complication rates (9.6% vs 11.1%) were similar between groups.
- Reoperation rates were higher in the early cases group (14.8%) compared to the later cases group (8.1%).
Conclusions:
- The study provides some evidence for improved success with later ab interno gelatin microstent placement.
- Early adoption by surgeons is feasible, with potential for improved outcomes as experience grows.
- Similar needling and complication rates suggest a manageable safety profile during the learning curve.
