Authors: Jeb A. Ong, Matthew B. Schlenker, Fady Sedarous, Andrei-Alexandru Szigiato, Husayn Gulamhusein, Paul Harasymowycz, Michael Dorey, Maryam Abtahi, Barend Zack, Delan Jinapriya, Iqbal Ike K. Ahmed

Author Disclosure Block: J.A. Ong: None. M.B. Schlenker: Consultant or Honoraria: Alcon, Allergan, Aequus, Johnson & Johnson, Light Matter Interaction, Santen, Thea-Labtician. F. Sedarous: None. A. Szigiato: None. H. Gulamhusein: None. P. Harasymowycz: Research Consultant: Allergan, Inc. M. Dorey: Research Consultant: Allergan, Inc. M. Abtahi:None. B. Zack: Research Consultant: Allergan, Inc. D. Jinapriya: None. I.K. Ahmed: Consultant, Speakers honoraria, or Research Grant/Support: Acucela, Aerie Pharmaceuticals, Alcon, Allergan, ArcScan, Bausch and Lomb, Beaver Visitec, Camras Vision, Carl Zeiss Meditec, Centervue, Ellex, ElutiMed, Equinox, ForSight Labs, Genentech, Glaukos,, Gore, Iantech, InjectSense, Iridex, iStar, Ivantis, Johnson & Johnson Vision, KeLoTec, LayerBio, Leica Microsystems, MicroOptx, New World Medical, Omega Ophthalmics, PolyActiva, Sanoculis, Santen, Science Based Health, Sight Sciences, Stroma, TrueVision, Vizzario, Alcon, Allergan, Carl Zeiss Meditec, Johnson & Johnson Vision, Aerie Pharmaceuticals, Alcon, Allergan, Camras Vision, Glaukos, Ivantis, Johnson & Johnson Vision, New World Medical, Santen.

Abstract Body:

Purpose: To compare the surgical success and safety of early compared to later surgical cases in patients receiving an ab-interno gelatin microstent with mitomycin C.
Study Design: Retrospective interventional cohort study.
Methods: A multicentre propensity score matched cohort study, including 6 glaucoma surgeons across 4 Canadian sites was conducted. Early cases conducted by fellows were also included as additional separate surgeons. Exclusion criteria included atypical forms of glaucoma, previous glaucoma, retinal or corneal surgery, and <1 month of follow-up. The primary outcome was hazard ratio of failure, defined as IOP <6 with >2 lines of vision loss, or >17 on no medications on 2 consecutive visits despite in-clinic maneuvers (including needling) >1 month post-operatively1. Surgeons’ first 20 cases (EC) were matched to cases with the closest propensity score from the later (21+) cases (LC) respectively. The propensity score regression coefficients included: age, gender, race, OD or OS, glaucoma type, BCVA, presence of diabetes, pseudophakia, disease severity, decision IOP, number of medications, and previous trabeculoplasty. Secondary outcomes were HRs for failure defined as IOP of 6-14 and 6-21mmHg, as well as medications, interventions, complications, and reoperations.
Results: 157 eyes in the EC group were propensity score matched to eyes from the LC group in a 1:1 ratio. Median decision IOP was 20.0 (16.0-24.0) and 21.0 (18.0-26.0) mmHg and median pre-operative mean deviation was -11.4 (-17.0 to -4.7) dB and -10.1 (-19.6 to -4.6) dB. HR of failure for 6-17 was 1.45 (1.00-2.09) in the EC group compared to the LC group, 1.51 (1.05-2.18) for 6-14, and 1.51 (1.04-2.19) for 6-21 without medication and 1.08 (0.65-1.79), 1.27 (0.78-2.03), 0.97 (0.54-1.74) allowing for medications. Complete success rates at 1 year were 0.48 (SE 0.05) and 0.53 (SE 0.05) respectively for the EC and LC groups and qualified was 0.82 (SE 0.04) and 0.81 (SE 0.04). Needling rates were 40.8% (EC20) and 34.4% (LC), with a HR for needling of 1.10 (0.69-1.76). Complications after 1 month occurred in 18.1% (EC), and 10.3% (LC) of eyes (p=0.073). Reoperation was undertaken in 13.4% (EC) and 15.3% (LC) of eyes (p=0.748).
Conclusions: In a Canadian multicentre retrospective study of consecutive cases, success rate was higher and complication rate lower in surgeons with 20 case experience with the ab-interno gelatin microstent.