Dahan 2012.

Study characteristics
Methods	Study design: paired‐eye randomized controlled trial Country: South Africa Number randomized: 30 eyes of 15 participants total; each participant had 1 eye in each intervention group Exclusions after randomization: none reported Losses to follow‐up: 0 up to 1 year after surgery; 1 participant died at 13 months and 2 were subsequently lost to follow‐up Unit of analysis: eye Number analyzed: 30 eyes of 15 participants total; each participant had 1 eye in each intervention group How were missing data handled? no missing data at 1 year Power calculation: a power of 96% to detect a 2 mmHg IOP difference between groups
Participants	Mean age: 65 years; not reported by intervention group Gender: 10/15 (67%) men and 5/15 (33%) women; not reported by intervention group Inclusion criteria: aged ≥ 18 years and presented with medically uncontrolled POAG requiring bilateral incisional surgery for IOP reduction. Patients with prior cataract operation or failed filtration surgery in either eye were eligible if surgery took place ≥ 3 months prior to enrolment Exclusion criteria: any form of glaucoma other than POAG; history of active uveitis; any ocular abnormality that would preclude accurate IOP assessment Equivalence of baseline characteristics: yes
Interventions	Intervention 1: trabeculectomy + MMC + Ex‐PRESS X200 Intervention 2: trabeculectomy + MMC Length of follow‐up Planned: ≥ 1 year Actual: all participants followed ≥ 1 year; the longest follow‐up visit for a participant was 30 months
Outcomes	Primary and secondary outcomes not distinguished Outcomes, as reported: IOP, visual acuity, number of medicines for IOP control, complications Intervals at which outcomes assessed: 1 and 7 days; 1, 3, 6, 9, 12, 18, 24, and 30 months after surgery
Notes	Publication type: published article Funding sources: (quote) "the study was supported by a financial grant from Alcon Laboratories." Disclosures of interest: "E Dahan is a paid consultant in Alcon Laboratories. GJ Ben Simon and A Lafuma has no financial or proprietary interest in any of the drugs or materials mentioned in this study. A Lafuma is employed by CEMKAEVAL, a company that provides services in statistical analyses and epidemiology." Trial registry: NCT00698438 Study period: not reported Subgroup analyses: none reported Publication language: English Study authors contacted and outcome data shared (IOP reduction, number of medications, and mean IOP at 1 and 7 days; and 1, 3, 6, 12, 18, 24, and 30 months after surgery)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Randomisation of contralateral operations was achieved by opening an envelope in which the procedure (trabeculectomy or Ex‐PRESS implantation) that would be applied to the first eye was stated, thereby determining the procedure in the other eye." Comment: the method of randomization was not described and thus its adequacy could not be judged.
Allocation concealment (selection bias)	Unclear risk	Allocation concealment was not reported.
Masking of participants and personnel (performance bias)	Low risk	Because trabeculectomy is a surgical procedure with informed consent, masking of the participants and personnel becomes impossible. However, given that (quote) "after sub‐tenonian local anaesthesia, surgery was performed by one experienced surgeon (ED), for consistency, using a standardized technique for both procedures," the risk of performance bias was comparably low for a surgical procedure.
Masking of outcome assessment (detection bias)	High risk	The study mentioned: (quote) "It was not possible to mask the surgical technique as trabeculectomy is easily differentiated from Ex‐PRESS implantation during postoperative follow‐ups. However, this limitation is overcome by the fact that all patients were followed up concurrently by their referring ophthalmologists from the first month postoperatively till completion of the study." Comment: although it was not possible to mask outcome assessors, devices could be easily seen during exam of the eye.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "All 15 patients were followed‐up for 12 months after surgery. One patient died 13 months after surgery and two patients were subsequently lost to follow‐up. All data available for these patients (i.e., up to 1 year) are included in the analyses."
Selective reporting (reporting bias)	Low risk	The study was registered at www.ClinicalTrials.gov. All defined outcomes in www.ClinicalTrials.gov were reported in full text. Complete and qualified success was reported and defined using IOP.
Other bias	High risk	Received industry monetary support from device manufacturer; (quotes) "ED is a paid consultant to Alcon Laboratories." "The study was supported by a financial grant from Alcon Laboratories." To consider intraperson correlation between eyes, the analysis used Wilcoxon matched‐pairs t‐test to compare preoperative and final IOP values. No other sources of bias identified.