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Journal Club
Clinical Paper of the Month - Ab-externo MicroShunt versus Trabeculectomy in Primary Open-Angle Glaucoma: 1-year Results from a 2-year Randomized, Multicenter Study
Ab-externo MicroShunt versus Trabeculectomy in Primary Open-Angle Glaucoma: 1-year Results from a 2-year Randomized, Multicenter Study

Publishing date: June 2021

Author(s): N Douglas Baker (1), Howard S Barnebey (2), Marlene R Moster (3), Michael C Stiles (4), Steven D Vold (5), Anup K Khatana (6), Brian E Flowers (7), Davinder S Grover (8), Nicholas G Strouthidis (9), Joseph F Panarelli (10), INN005 study group

1 Ophthalmic Surgeons and Consultants of Ohio, Columbus, OH, USA.
2 Specialty Eyecare Centre, Bellevue, WA, USA.
3 Wills Eye Hospital, Philadelphia, PA, USA.
4 Stiles Eyecare Excellence, Overland Park, KS, USA.
5 Vold Vision, Fayetteville, AR, USA.
6 Cincinnati Eye Institute, Cincinnati, OH, USA.
7 Ophthalmology Associates, Fort Worth, TX, USA.
8 Glaucoma Associates of Texas, Dallas, TX, USA.
9 NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK; Discipline of Clinical Ophthalmology and Eye Health, University of Sydney, Sydney, NSW, Australia.
10 New York University, New York, NY, USA. Electronic address:

OBJECTIVE: To compare the effectiveness and safety of the MicroShunt versus trabeculectomy in patients with primary open-angle glaucoma (POAG).

DESIGN: One-year results from a 2-year, prospective, randomized, multicenter, non-inferiority study (NCT01881425) conducted in the USA and Europe.

PARTICIPANTS: Eligible patients were aged 40-85 years with intraocular pressure (IOP) ≥15 and ≤40 mmHg and mild-to-severe POAG inadequately controlled on maximum tolerated medical therapy.

INTERVENTION: Patients were randomized 3:1 to undergo stand-alone MicroShunt implantation or trabeculectomy, both performed with adjunctive Mitomycin C (0.2 mg/mL for 2 minutes).

MAIN OUTCOME MEASURES: The primary effectiveness endpoint was surgical success, defined as ≥20% reduction in mean diurnal IOP from baseline (no medication washout) at year 1 without increasing the number of glaucoma medications. Secondary effectiveness endpoints at year 1 were the mean IOP change from baseline and requirement for postoperative intervention. Additional endpoints included glaucoma medication use and adverse events.

RESULTS: Overall, 395 (MicroShunt) and 132 (trabeculectomy) patients were randomized (mean Humphrey visual field mean deviation -12.34 dB). At year 1, probability of success was lower in the MicroShunt group compared with the trabeculectomy group (53.9% versus 72.7%, respectively; P<0.01). In the MicroShunt group, mean IOP ± standard deviation decreased from 21.1±4.9 mmHg at baseline to 14.3±4.3 mmHg (-29.1%; P<0.01) at year 1, with a mean of 0.6±1.1 glaucoma medications (baseline 3.1±1.0; P<0.01). In the trabeculectomy group, mean IOP decreased from 21.1±5.0 mmHg to 11.1±4.3 mmHg (-45.4%; P<0.01), with a mean of 0.3±0.9 glaucoma medications (baseline 3.0±0.9; P<0.01). Postoperative interventions, including laser suture lysis, were reported in 40.8% (MicroShunt) versus 67.4% (trabeculectomy) of patients (P<0.01). Reported incidence of transient hypotony was higher in the trabeculectomy group versus the MicroShunt group (49.6% versus 28.9%; P<0.01). Vision-threatening complications were uncommon and reported in 1.0% of MicroShunt versus 0.8% of trabeculectomy patients.

CONCLUSIONS: Probability of success was lower with MicroShunt compared with trabeculectomy. Though reductions in IOP and glaucoma medications over 1 year were observed in both groups, the trabeculectomy group had a lower mean IOP on fewer medications.

Copyright © 2021. Published by Elsevier Inc.

Ophthalmology. 2021 May 26;S0161-6420(21)00384-5. doi: 10.1016/j.ophtha.2021.05.023.

PMID: 34051211

Clinical Paper of the Month manager: Anthony Khawaja
Editorial Board: Humma Shahid, Karl Mercieca, Francisco Goni
Editors in Chief: Francesco Oddone, Manuele Michelessi

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