Gui‐Hong 2018.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: parallel group Number randomly assigned: 240 eyes, 120 participants Exclusions after randomization: not reported Number analyzed: 240 eyes, 120 participants Unit of analysis: eye Losses to follow‐up: not reported Handling of missing data: not reported Power calculation: not reported Study dates: June 2014 to May 2015
Participants	Country: China Overall mean age: 27.2 years (SD 3.2) Age range: 19 to 44 years Gender: women 54%, men 46% Setting: not reported Equivalence of baseline characteristics: yes Inclusion criteria: people with myopia Exclusion criteria: not reported
Interventions	Laser for ablation: not reported Intervention 1 Intervention: LASIK with a microkeratome Flap dimensions: not reported Number of people randomized: 120 eyes, 60 participants Length of follow‐up: Planned: not reported Actual: 6 months Intervention 2 Intervention: LASIK with a femtosecond laser Flap dimensions: not reported Number of people randomized: 120 eyes, 60 participants Length of follow‐up: Planned: not reported Actual: 6 months
Outcomes	Mean UCVA after surgery Intervals at which outcome assessed: 1 week, and 1 and 6 months Planned follow‐up: not reported Actual follow‐up: 6 months Scale: logMAR Instrument for measurement: not reported Mean spherical equivalent of the refractive error after surgery Intervals at which outcome assessed: 1 week, and 1 and 6 months Planned follow‐up: not reported Actual follow‐up: 6 months Scale: D Instrument for measurement: not reported
Identification	Sponsorship source: not specified Country: China Setting: Institute of Ophthalmology Comments: none Author's name: Xiao – Hong Gu Institution: Gu's Eye Hospital Email: 3235745327@qq. com Address: Luohe 462000, Henan Province, China
Notes	Trial registration number: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: method of sequence generation not described
Allocation concealment (selection bias)	Unclear risk	Comment: method of concealment not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: trial did not describe masking participants or trial personnel
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: trial did not describe masking of outcome assessors
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: unclear whether all participants randomized were analyzed
Selective reporting (reporting bias)	Unclear risk	Comment: no published trial protocol with which to compare
Other bias	Low risk	Comment: trial appeared free of other sources of bias