Biedner 1998.

Study characteristics
Methods	Study design: controlled clinical trial, paired‐eye design Number randomized (total and per group): 7 children with 14 eyes; 7 right eyes underwent combined trabeculotomy‐trabeculectomy, and 7 left eyes underwent trabeculotomy alone Number analyzed (total and per group): all children completed 6 months follow‐up; 6/7 children completed at least 1 year follow‐up Losses to follow‐up: not reported Length of follow‐up: Planned: a minimum of 6 months Actual: 40.29 ± 27.96 months Sample size calculation (Y/N): N
Participants	Country: Israel Age: trabeculotomy‐trabeculectomy combined group: 3.43 ± 3.31 weeks; trabeculotomy‐alone group: 4.86 ± 3.89 weeks Gender: not reported Inclusion criteria: bilateral congenital glaucoma, younger than 3 months of age Equivalence of baseline characteristics: each surgery was performed on the two eyes of the same participant. Ages at time of surgery differed by design (the right eye was always operated on first; the average time interval between the two procedures was 1.43 ± 1.62 weeks).
Interventions	Intervention 1: trabeculotomy‐trabeculectomy combined procedure Intervention 2: trabeculotomy alone
Outcomes	Outcomes: IOP before surgery and at the end of follow‐up Complications during follow‐up Intervals at which outcome assessed: IOP was measured at the last follow‐up of each participant Issues with outcome assessment: none Adverse effects: choroidal detachment, hyphema, shallow anterior chambers, corneal opacities, flat, diffuse filtering blebs
Notes	Type of study: published Funding: not reported Declaration of interest: not reported Study period: 1988 to 1995 Clinical trial registry: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	"The right eye underwent the trabeculotomy‐trabeculectomy combined procedure, and the left eye underwent trabeculotomy alone, regardless of the IOP recorded."
Allocation concealment (selection bias)	High risk	Allocation was not concealed.
Masking of participants and personnel (performance bias)	Unclear risk	The surgeon could not be masked. Not masking young children/infants is unlikely to introduce bias.
Masking of outcome assessment (detection bias)	Unclear risk	We do not know whether outcome assessors were masked.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Six out of seven children completed one‐year follow‐up.
Selective reporting (reporting bias)	Unclear risk	The protocol was not available. Outcomes prespecified in the Methods section matched the outcomes reported in the Results section.
Other bias	Unclear risk	Source of funding and conflicts of interest were not reported.