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Vinay Kansal, Yogesh Patodia, Matthew Schlenker, Devesh Varma, Iqbal Ahmed; Efficacy of targeted versus non-targeted trabecular micro-bypass stents. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2060.
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In effort to improve intraocular pressure (IOP) reduction outcomes of trabecular micro-bypass stents, some operators are now employing a targeted placement technique where the device is implanted near large, pulsatile episcleral vessels draining Schlemm’s canal. The purpose of this study was to compare the efficacy of targeted vs. non-targeted implantation of trabecular micro-bypass stents.
Single-center, retrospective, investigational cohort study. 170 eyes, 134 patients with ≥2 months follow-up that had micro-bypass stent implantation at Trillium Health Partners (Mississauga, Canada) from Jan. 2010 to September. 2017. 78 eyes targeted implantation, 99 non-targeted. Primary outcome: IOP≤21mHg and on fewer IOP-lowering medications on last follow up vs. baseline. Secondary outcomes: 1) IOP≤18, no medications, and 2) ≥20% IOP reduction, no medication increase. Baseline characteristics were compared with Fisher Exact tests and Wilcoxon rank sum tests. Mixed effects model calculated using generalized estimating equations adjusted for baseline characteristics and accounting for correlation between eyes was used to compare interventions.
Baseline characteristics were similar between groups with these exceptions: targeted group had more IOP-reducing medications (2.9 vs 2.4, p<0.01), and longer median follow up (13.0 vs. 12.1 months, p<0.05). Median baseline IOP was similar between groups (17.4mmHg in targeted group vs. 16.0mmHg non-targeted, p=0.08). 92.3% (96.5-83.9) of targeted eyes achieved the primary outcome versus 81.8% (73.0-88.2) of non-targeted eyes, (adjusted OR 2.7 [95% CI 1.1-7.1]). There was insufficient evidence to conclude a difference in the percentage of patients achieving the secondary outcomes between groups.
Targeted micro-bypass stent implantation has the theoretical impact of improved IOP control by directing aqueous outflow toward segments of the trabecular meshwork that are more likely draining toward episcleral vessels with improved flow. In this investigation, targeted micro-bypass implantation was more likely than non-targeted to achieve IOP≤21mmHg on less medication. No difference was identified for other success criteria. While regression adjusted for baseline characteristics, unmeasured confounders cannot be accounted for. Future studies should be randomized, prospective, and assess washed out IOP.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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