Wagschal 2015.

Study characteristics
Methods	Study design: parallel‐group randomized controlled trial Country: Canada Number randomized: 64 eyes of 64 participants total 33 participants in trabeculectomy + MMC + Ex‐PRESS P50 group 31 participants in trabeculectomy + MMC group Exclusions after randomization: none reported Losses to follow‐up: 4 participants total at 1 year 3 participants in trabeculectomy + MMC + Ex‐PRESS P50 group 1 participant in trabeculectomy + MMC group Unit of analysis: individual (1 eye per participant) Number analyzed: 60 participants total; 30 participants in each group How were missing data handled? 4 participants excluded from analysis Power calculation: a power of 80% to detect a 2 mmHg IOP difference with a sample size of 52 eyes
Participants	Mean age: overall not reported 61.9 years for trabeculectomy + MMC + Ex‐PRESS P50 group 65.9 years for trabeculectomy + MMC group Gender: 41/64 (64%) men and 23/64 (36%) women overall; not reported by intervention group Inclusion criteria: aged 18–85 years with OAG and uncontrolled IOP on maximum tolerated medication and trabeculectomy as the planned surgical procedure Exclusion criteria: previous ocular incisional surgery (except for clear cornea cataract surgery or 1 trabeculectomy), history of uveitis, unwilling or unable to give consent, unwilling to accept randomization, or unable to return for scheduled protocol visits Equivalence of baseline characteristics: yes; baseline IOP and visual acuity were comparable
Interventions	Intervention 1: trabeculectomy + MMC + Ex‐PRESS P50 Intervention 2: trabeculectomy + MMC Length of follow‐up Planned: 1 year Actual: 1 year
Outcomes	Primary outcome, as defined: IOP, complete success ("IOP between 5 and 18 mmHg and a 20% reduction from baseline without medication and qualified success was defined as above with hypotensive medications"), failure ("reoperation for glaucoma or loss of light perception") Secondary outcomes, as defined: visual acuity, surgery time, glaucoma medication usage, IOP, bleb morphology, Seidel test, additional procedures, complications, and potential risk factors for vision loss Intervals at which outcomes assessed: 1 day; 1 and 2 weeks; and 1, 2, 3, and 6 months after surgery
Notes	Publication type: published article Funding sources: (quote) "some Ex‐PRESS shunts were provided at no cost by Imed and Alcon Canada" Disclosures of interest: (quote) "Y.M.B. has received speaking honoraria from Alcon Canada. The remaining authors declare no conflict of interest." Trial registry: NCT01263561 Study period: May 2009 to July 2011 Subgroup analyses: subgroup of 43 participants randomly chosen for cost‐effectiveness analysis Publication language: English Authors contacted for randomization method, reasons for lost to follow‐up, etc.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	As this was not provided in the published report, we contacted the study investigator, and received the following response: (quote) "randomization was done by drawing a piece of paper with procedure name from a bag."
Allocation concealment (selection bias)	Unclear risk	Not reported.
Masking of participants and personnel (performance bias)	Unclear risk	By contacting the study investigators, we found participants were not masked, but whether this would introduce bias was uncertain as current evidence did not show 1 procedure significantly better than the other.
Masking of outcome assessment (detection bias)	High risk	By contacting the study investigators, we found the outcome assessors were not masked. Although it is not possible to mask outcome assessors, devices can be easily seen during exam of the eye.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Study had 4/64 participants lost to follow‐up, and little difference in numbers in the 2 groups (lost 3 versus 1). Also, exclusions were due to death (3 participants) and 1 participant not adhering to the assigned procedure.
Selective reporting (reporting bias)	Low risk	Study registered in www.ClinicalTrials.gov. All defined outcomes in www.ClinicalTrials.gov were reported in full text.
Other bias	Unclear risk	Partial industry support and other source(s) of potential bias.

ACG: angle‐closure glaucoma; BCVA: best‐corrected visual acuity; dB: decibel; IOP: intraocular pressure; MMC: mitomycin C; NVG: neovascular glaucoma; OAG: open‐angle glaucoma; PEXG: pseudoexfoliation glaucoma; POAG: primary open‐angle glaucoma; SD: standard deviation.