Intermediate Safety and Efficacy Outcomes of the Novel 63μm Gelatin Microstent versus the Conventional 45μm Gelatin Microstent

Authors: Isra M. Hussein ¹, Ticiana De Francesco², Iqbal Ike K. Ahmed¹. ¹University of Toronto, ²Hospital de Olhos Leiria de Andrade.

Author Disclosures: I.M. Hussein: None. T. De Francesco: Any direct financial payments including receipt of honoraria; Name of for-profit or not-for-profit organization(s); Sight Sciences, Allergan, ViaLase, Elios, Iantrek. I.K. Ahmed: Any direct financial payments including receipt of honoraria; Name of for-profit or not-for-profit organization(s); Aequus, Ace Vision, Aerie Pharmaceuticals, Akorn, Alcon, Allergan, Aquea Health, Inc, ArcScan, Avellino Lab USA, Inc, Avisi, Bausch Health, Beaver Visitec, Beyeonics, Bionode, Carl Zeiss Meditec, Centricity Vision, Inc, CorNeat Vision, Custom Surgical, Elios Vision, ElutiMed, Equinox, eyeFlow, Inc, Exhaura Limited, Genentech, Glaukos, Gore, Heine, Heru, Iantrek, InjectSense, Iridex, iStar, Ivantis, Johnson & Johnson Vision, Labtician Thea, LayerBio, Leica Microsystems, Life Long Vision, Long, Bridge Medical, Inc, MicroOptx, MST Surgical, Myra Vision, New World Medical, NovaEye, Ocular Instruments, Ocular Therapeutix, Oculo, Oculus Surgical, Omega Ophthalmics, PolyActiva, PulseMedica, Radiance Therapeutics, Inc, Ripple Therapeutics, Sanoculis, Santen, Shifamed, LLC, Sight Sciences, Smartlens, Inc, Strom, Thea Pharma, ViaLase, Visus Therapeutics, Vizzario, VSY Biotechnology, Zilia, Inc. Funded grants or clinical trials; Name of for-profit or not-for-profit organization(s); Aerie Pharmaceuticals, Alcon, Allergan, Bionode, Glaukos, iCare, Ivantis, Johnson & Johnson Vision, New World Medical, Santen. 
 

Abstract Body: 

Purpose: To determine intermediate safety and efficacy outcomes at 1 year in a consecutive cohort of glaucoma patients that underwent 63 μm gelatin microstent (Xen63) implantation with mitomycin C (MMC) compared to patients that underwent 45 μm gelatin microstent (Xen45) implantation with MMC. 

Study Design: Single centre, consecutive , retrospective cohort study 

Methods: Consecutive patients that underwent Xen63 implantation with MMC at a single centre, were compared to matched controls who underwent Xen45 implantation with MMC. Standalone and cases combined with phacoemulsification were included. Primary outcome was the hazard ratio of failure at 12-months of Xen45 vs. Xen63 eYes, with failure defined as 2 consecutive IOPs, (1)>17 mmHg, (2)<6 mmHg with 2 lines of vision loss, or (3)<20% reduction from baseline IOP, without (complete) or with (qualified) glaucoma medications. Secondary outcomes included IOP thresholds of 14 mmHg and 21 mmHg, postoperative IOP, medications, adverse events, interventions, and reoperations. 

Results: 84 eyes were included (Xen63, n=42; Xen45, n=42); 52.4% with an open conjunctival approach, 26.2% combined with phacoemulsification, and 10.7% in patients with refractory glaucoma. Overall, the treatment groups had similar baseline characteristics. 12-month complete success rate was higher in the Xen63 group (59.5% vs. 28.6%, p=0.009) at the primary IOP threshold of 6 to 17 mmHg but did not differ significantly for qualified success (66.7% vs. 45.2%, p=0.08). The crude hazard ratio of failure of Xen45 relative to Xen63 was 2.28 (1.21-4.32) for the primary IOP threshold of 6-17 mmHg. At 12 months, Xen63 eyes had significantly lower mean IOP (12.7 ±4.8mmHg vs. 15.5 ±5.1mmHg, p=0.001) and fewer medication classes (0.6 ±1.1 meds vs. 1.7 ±1.6 meds, p=0.0005), with the degree of reduction in IOP and medication count being significantly greater in Xen63 eye. There were 29 and 22 distinct interventions in Xen63 and Xen45 eyes respectively, with 11.9% of eyes undergoing needling in each treatment group. There were 38 and 26 distinct adverse events, in Xen63 and Xen45 eyes respectively, most of which were early and transient. Nine Xen63 eyes (21.4%) and 6 Xen45 eyes (14.3%) had a reoperation for glaucoma.

Conclusions: The Xen63 microstent resulted in greater surgical success rates compared to the Xen45 microstent and demonstrated superior efficacy in terms of IOP and medication reduction. This was tempered by more postoperative interventions and adverse events, although these were often early and transient. The efficacy and safety profile of Xen63 is promising, but further evaluation is required.