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Risk of bias assessment of randomised controlled trials in high-impact ophthalmology journals and general medical journals: a systematic review
  1. Lazar Joksimovic1,
  2. Robert Koucheki1,
  3. Marko Popovic2,
  4. Yusuf Ahmed3,
  5. Matthew B Schlenker4,5,
  6. Iqbal Ike K Ahmed4,5,6
  1. 1Faculty of Arts & Science, University of Toronto, Toronto, Canada
  2. 2Faculty of Medicine, University of Toronto, Toronto, Canada
  3. 3Schulich School of Medicine & Dentistry, Western University, London, Canada
  4. 4Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada
  5. 5Prism Eye Institute, Mississauga, Ontario, Canada
  6. 6Department of Ophthalmology, Trillium Health Partners, Mississauga, Ontario, Canada
  1. Correspondence to Dr Iqbal Ike K Ahmed, Prism Eye Institute, 3200 Erin Mills Parkway, Unit 1, Mississauga, Ontario, L5L 1W8, Canada; ike.ahmed{at}


Evidence-based treatments in ophthalmology are often based on the results of randomised controlled trials. Biased conclusions from randomised controlled trials may lead to inappropriate management recommendations. This systematic review investigates the prevalence of bias risk in randomised controlled trials published in high-impact ophthalmology journals and ophthalmology trials from general medical journals. Using Ovid MEDLINE, randomised controlled trials in the top 10 high-impact ophthalmology journals in 2015 were systematically identified and critically appraised for the prevalence of bias risk. Included randomised controlled trials were assessed in all domains of bias as defined by the Cochrane Collaboration. In addition, the prevalence of conflict of interest and industry sponsorship was investigated. A comparison with ophthalmology articles from high-impact general medical journals was performed. Of the 259 records that were screened from ophthalmology-specific journals, 119 trials met all inclusion criteria and were critically appraised. In total, 29.4% of domains had an unclear risk, 13.8% had a high risk and 56.8% had a low risk of bias. In comparison, ophthalmology articles from general medical journals had a lower prevalence of unclear risk (17.1%), higher prevalence of high risk (21.9%) and a higher prevalence of low risk domains (61.9%). Furthermore, 64.7% of critically appraised trials from ophthalmology-specific journals did not report any conflicts of interest, while 70.6% did not report an industry sponsor of their trial. In closing, it is essential that authors, peer reviewers and readers closely follow published risk of bias guidelines.

  • randomized controlled trial
  • risk of bias
  • ophthalmology

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  • Contributors Conception and design: LJ, RK, MP and IIKA. Data collection: LJ, RK, MP and YA. Analysis and interpretation: LJ, RK, MP, MBS and IIKA. Overall responsibility: LJ, RK, MP, YA, MBS and IIKA.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.