. 2020 Apr 7;2020(4):CD012309. doi: 10.1002/14651858.CD012309.pub2

You 2001.

Methods	Study design: randomized controlled trial, parallel group Unit of analysis: participants Number randomized: 46 participants, 16 in the 0.2 mg/mL MMC group, 16 in the 0.5 mg/mL MMC group, 18 in the EX‐DCR alone group Number of arms: 3 Enrollment start year: 1996 Length of follow‐up: range 23 to 42 months Sample size calculations: not reported Losses to follow‐up: 4
Participants	Country: China Age (mean (SD)): 33.13 (13.17) in the 0.2 mg/mL MMC group, 30.18 (12.74) in the 0.5 mg/mL MMC group, 33.64 (11.89) in the EX‐DCR alone group Females (n (%)): 33 (72) in total, 11 (69) in the 0.2 mg/mL MMC group, 10 (62) in the 0.5 mg/mL MMC group, 12 (67) in the EX‐DCR alone group Inclusion criteria: primary nasolacrimal duct obstruction, duration of symptoms longer than 1 year Exclusion criteria: canalicular or common canalicular stenosis or obstruction ascertained by probing or dacryocystography, epiphora with a positive primary Jones dye test, acute dacryocystitis, tumor of the lacrimal sac, severe atrophic rhinitis Study group differences: not reported
Interventions	Intervention 1: EX‐DCR with application of 0.2 mg/mL MMC Intervention 2: EX‐DCR with application of 0.5 mg/mL MMC Comparison intervention: EX‐DCR alone
Outcomes	Measured outcomes: functional success, defined as the relief of epiphora anatomic success, defined as patency to lacrimal irrigation ostium size on nasal endoscopy at 6 months postoperatively Adverse events: mild postoperative hemorrhage
Identification	Author name: Yi‐an You Institution: First Affiliated Hospital, Wenzhou Medical College Email: not reported
Notes	Funding source: not reported Declarations of interest: none Trial registration number: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants were randomly assigned to treatment, method of randomization not reported.
Allocation concealment (selection bias)	Unclear risk	How allocation of participants to treatment was concealed is not described.
Blinding of participants and personnel (performance bias)   All outcomes	Unclear risk	Whether participants and personnel were masked is not described.
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	Whether outcome assessors were masked is not described.
Incomplete outcome data (attrition bias)   All outcomes	Low risk	There was wide range of follow‐up: "Follow‐up time intervals ranged from 23 to 42 months (mean, 35.2 5.3 months)", and analysis appears not to be intention‐to‐treat, as 4 lost to follow‐up were not included in the analysis. The number lost to follow‐up was small and is unlikely to have impacted on results.
Selective reporting (reporting bias)	Unclear risk	No trial or protocol registration available for comparison to ascertain selective outcome reporting.
Other bias	Unclear risk	There was insufficient information to permit a judgement of 'low risk' or 'high risk'.

DCR: dacryocystorhinostomy  ECL‐DCR: endocanalicular dacryocystorhinostomy  ELDCR: endonasal laser dacryocystorhinostomy  EN‐DCR: endonasal dacryocystorhinostomy  EX‐DCR: external dacryocystorhinostomy  FU: fluorouracil  MMC: mitomycin‐C  NLDO: nasolacrimal duct obstruction  NR: not reported  SD: standard deviation  TLA‐ELA DCR: endonasal and endocanalicular dacryocystorhinostomy with diode laser  5‐FU:5‐fluorouracil