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Association between vision impairment and mortality: protocol for a systematic review and meta-analysis
  1. Joshua R Ehrlich1,2,
  2. Jacqueline Ramke3,4,
  3. David Macleod4,5,
  4. Bonnielin K Swenor6,7,
  5. Helen Burn8,
  6. Chan Ning Lee4,9,
  7. William J Waldock10,
  8. Justine H Zhang4,11,
  9. Iris Gordon4,
  10. Nathan Congdon12,13,
  11. Matthew Burton4,14,
  12. Jennifer R Evans4
  1. 1Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, USA
  2. 2Institute for Healthcare Policy and Innovation, University of Michigan, Ann Arbor, Michigan, USA
  3. 3School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
  4. 4International Centre for Eye Health, London School of Hygiene and Tropical Medicine, London, UK
  5. 5MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
  6. 6Ophthalmology, Johns Hopkins University, Baltimore, Maryland, USA
  7. 7Epidemiology, Johns Hopkins University, Baltimore, Maryland, USA
  8. 8Ophthalmology Department, Stoke Mandeville Hospital, Aylesbury, Buckinghamshire, UK
  9. 9St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
  10. 10School of Clinical Medicine, University of Cambridge, Cambridge, Cambridgeshire, UK
  11. 11Manchester Royal Eye Hospital, Manchester, UK
  12. 12Global Eye Health, Queen's University Belfast, Belfast, UK
  13. 13Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
  14. 14Moorfields Eye Hospital, London, UK
  1. Correspondence to Dr Joshua R Ehrlich; joshre{at}


Introduction Due to growth and ageing of the world’s population, the number of individuals worldwide with vision impairment (VI) and blindness is projected to increase rapidly over the coming decades. VI and blindness are an important cause of years lived with disability. However, the association of VI and blindness with mortality, including the risk of bias in published studies and certainty of the evidence, has not been adequately studied in an up-to-date systematic review and meta-analysis.

Methods and analysis The planned systematic review and meta-analysis will adhere to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Databases, including MEDLINE Ovid, Embase Ovid and Global Health, will be searched for relevant studies. Two reviewers will then screen studies and review full texts to identify studies for inclusion. Data extraction will be performed, and for included studies, the risk of bias and certainty of the evidence will be assessed using the Grades of Recommendation, Assessment, Development and Evaluation approach. The prognostic factor in this study is visual function, which must have been measured using a standard objective ophthalmic clinical or research instrument. We will use standard criteria from WHO to categorise VI and blindness. All-cause mortality may be assessed by any method one or more years after baseline assessment of vision. Results from included studies will be meta-analysed according to relevant sections of the Meta-analysis Of Observational Studies in Epidemiology checklist.

Ethics and dissemination This review will only include published data; therefore, ethics approval will not be sought. The findings of this review and meta-analysis will be published in an open-access, peer-reviewed journal and will be included in the ongoing Lancet Global Health Commission on Global Eye Health.

  • ophthalmology
  • epidemiology
  • public health

This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See:

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  • Contributors All authors made substantive intellectual contributions to the development of this protocol. JRE, JR, MB and JE conceptualised the review approach. JRE drafted the first version. JR, MB and JE provided guidance to the research team. DM, BS, IG, NC, HB, CNL, WJW and JHZ developed the draft further. All authors were involved in revisions of the manuscript, developing review questions and the review design. All authors approved the final version of the manuscript. JRE and JE took overall responsibility for the content of this manuscript.

  • Funding MB is supported by grants from the Wellcome Trust (207472/Z/17/Z) to MB. JR is a Commonwealth Rutherford Fellow, funded by the UK government through the Commonwealth Scholarship Commission in the UK. BKS is supported by the National Institutes of Health (K01AG052640). JRE is supported by the National Institutes of Health (K23EY027848). The Lancet Global Health Commission on Global Eye Health is supported by The Queen Elizabeth Diamond Jubilee Trust, Moorfields Eye Charity (GR001061), NIHR Moorfields Biomedical Research Centre, The Wellcome Trust, Sightsavers, The Fred Hollows Foundation, The SEVA Foundation, The British Council for the Prevention of Blindness and Christian Blind Mission.

  • Disclaimer No funder had any role in the design or conduct of this work.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Patient consent for publication Not required.

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

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