Long-Term Outcomes of Ab-Interno Gelatin Microstent Implantation Alone vs. Combination with Phacoemulsification: Canadian Multicentre Study

Authors: Nishaant Bhambra, Matthew Schlenker, Iqbal Ike Ahmed. Prism Eye Institute.

Author Disclosures: N. Bhambra: Membership on advisory boards or speakers’ bureaus; Name of for-profit or not-for-profit organization(s); Valeo Pharmaceuticals. Membership on advisory boards or speakers’ bureaus; Description of relationship(s); Advisory board. M. Schlenker: Any direct financial payments including receipt of honoraria; Name of for-profit or not-for-profit organization(s); Alcon, Allergan, Light Matter Interaction, Santen. Any direct financial payments including receipt of honoraria; Description of relationship(s); Consultant. Membership on advisory boards or speakers’ bureaus; Name of for-profit or not-for-profit organization(s); Alcon, Allergan, Bausch Health, Johnson & Johnson Vision, Thea-Labtician. Membership on advisory boards or speakers’ bureaus; Description of relationship(s); Speaker honoraria. I. Ahmed: Any direct financial payments including receipt of honoraria; Name of for-profit or not-for-profit organization(s); Alcon, Allergan, Carl Zeiss Meditec, Johnson & Johnson Vision, MST Surgical, Aquea Health Inc, Centricity Vision Inc, Aequus, Aerie Pharmaceuticals, Akorn, ArcScan, Bausch Health, Beaver Visitec, Beyeonics, CorNeat Vision,Costum Surgical, ELT Sight, ElutiMed, Equinox, Genentech, Glaukos, Gore, Iantrek, InjectSense, Iridex, iStar, Ivantis, LayerBio, Leica Microsystems, Long Bridge Medical Inc, MicroOptx, New World Medical, Ocular Instruments, Ocular Therapeutix, Oculo, Omega Ophthalmics, PolyActiva, Ripple Therapeutics, Sanoculis, Santen, Sight Sciences, Smartlens Inc, Stroma, Thea Pharma, ViaLase, Vizzario, Radiance Therapeutics Inc, Shifamed LLC. Any direct financial payments including receipt of honoraria; Description of relationship(s); Consultant. Membership on advisory boards or speakers’ bureaus; Name of for-profit or not-for-profit organization(s); Alcon, Allergan, Carl Zeiss Meditec, Johnson & Johnson Vision, MST Surgical. Membership on advisory boards or speakers’ bureaus; Description of relationship(s); Speaker
honoraria.


Abstract Body: 

Purpose: To compare the long-term efficacy, safety, and complications of ab-interno gelatin microstent implantation with mitomycin C (MMC) as a solo procedure (standalone) or with phacoemulsification (combined) in glaucomatous eyes. 

Study Design: Canadian multicenter, retrospective, interventional cohort study. 

Methods: 974 eyes in 943 patients were enrolled. Exclusion criteria included atypical forms of or previous glaucoma, retinal or corneal surgery, and <1 month of follow-up. Baseline and postoperative IOP and medication use were compared using paired-samples t-test and Wilcoxon signed-rank test, respectively. Survival analysis was performed with failure defined as an IOP < 6, > 17 mmHg, or an IOP reduction of < 20% from baseline on 2 consecutive visits, or any reoperation, or any medications. Qualified success criteria used the same failure definition allowing for medications. A Cox proportional hazards model was used to determine hazard ratios and explore other risk factors for failure. Secondary outcomes included 14 and 21 mmHg thresholds, medications, adverse events (AEs), interventions, and reoperations. 

Results: 511 eyes received standalone and 443 received combined implantation. Median ages were 71.2 (IQR: 63.3-78.3) and 71.8 (65.4-77.0) for standalone and combined groups respectively. Mean baseline IOP was greater in the standalone group (20.2) than the combined group (16.4). Median pre-operative medication classes were 3 (IQR:2-4) for both groups. When requiring IOP < 17 mmHg and 20% IOP reduction, survival at last follow-up (F/U) was 26.2% for standalone (median F/U 19.6 months, IQR:11.6-41.8) and 19.4% for combined (median F/U:15.2 mos., 8.7-23.1) groups. Allowing medications, survival was 39.5% and 32.1% in standalone and combined groups. At last F/U, mean IOP (mmHg) decreased to 13.5 (standalone) and 13.9 (combined). Median medications decreased to 0 (IQR:0-0) for both groups. HR of failure for 6-14 was 1.51 (95% CI: 1.27-1.79) for combined relative to standalone cases, 1.55 (95% CI: 1.3-1.85) for 6-17, and 1.56 (1.3-1.87) for 6-21 without medication and 1.54 (1.29-1.85), 1.63 (1.35-1.97), 1.67 (1.37-2.03) allowing medications. AEs included choroidals (10.8% standalone, 12.4% combined), encapsulation (9.6%, 11.1%), hyphema (8.2%, 9.5%), and stent blockage (4.1%, 4.7%). Interventions included needling (38.9%, 44.9%) and digital ocular compression (25.6%, 29.6%). Reoperations included stent revision (7.6%, 8.8%), conjunctival suturing (2.2%, 2.5%), and stent explantation (1.8%, 2.0%). 

Conclusions: Our analysis finds a survival benefit in eyes receiving standalone gel stent implantation compared to gel stent with phacoemulsification for all IOP thresholds, with or without medication use. Reoperation, AE, and intervention rates were similar between groups. The data presented here should be interpreted while recognizing differences in each group’s baseline characteristics. Clinicians and patients may wish to consider the association between phacoemulsification and gel stent outcomes.

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