title: Suitability of UK Biobank Retinal Images for Automatic Analysis of Morphometric Properties of the Vasculature.
abstract: OBJECTIVE
  To assess the suitability of retinal images held in the UK Biobank--the largest retinal data repository in a prospective population-based cohort--for computer assisted vascular morphometry, generating measures that are commonly investigated as candidate biomarkers of systemic disease.
  
  
  METHODS
  Non-mydriatic fundus images from both eyes of 2,690 participants--people with a self-reported history of myocardial infarction (n=1,345) and a matched control group (n=1,345)--were analysed using VAMPIRE software. These images were drawn from those of 68,554 UK Biobank participants who underwent retinal imaging at recruitment. Four operators were trained in the use of the software to measure retinal vascular tortuosity and bifurcation geometry.
  
  
  RESULTS
  Total operator time was approximately 360 hours (4 minutes per image). 2,252 (84%) of participants had at least one image of sufficient quality for the software to process, i.e. there was sufficient detection of retinal vessels in the image by the software to attempt the measurement of the target parameters. 1,604 (60%) of participants had an image of at least one eye that was adequately analysed by the software, i.e. the measurement protocol was successfully completed. Increasing age was associated with a reduced proportion of images that could be processed (p=0.0004) and analysed (p<0.0001). Cases exhibited more acute arteriolar branching angles (p=0.02) as well as lower arteriolar and venular tortuosity (p<0.0001).
  
  
  CONCLUSIONS
  A proportion of the retinal images in UK Biobank are of insufficient quality for automated analysis. However, the large size of the UK Biobank means that tens of thousands of images are available and suitable for computational analysis. Parametric information measured from the retinas of participants with suspected cardiovascular disease was significantly different to that measured from a matched control group.
authors.affiliation: VAMPIRE project, Clinical Research Imaging Centre, University of Edinburgh, Edinburgh, United Kingdom; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom; Clinical Research Facility, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: MacGillivray
authors.affiliation: The Anne Rowling Regenerative Neurology Clinic, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: James R
authors.initials: JR
authors.lastname: Cameron
authors.affiliation: Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Qiuli
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Medical School, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Ahmed
authors.initials: A
authors.lastname: El-Medany
authors.affiliation: Medical School, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Carl
authors.initials: C
authors.lastname: Mulholland
authors.affiliation: Medical School, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Ziyan
authors.initials: Z
authors.lastname: Sheng
authors.affiliation: VAMPIRE project, School of Clinical Sciences, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Bal
authors.initials: B
authors.lastname: Dhillon
authors.affiliation: Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Fergus N
authors.initials: FN
authors.lastname: Doubal
authors.affiliation: National Institute for Health Research, Biomedical Research Centre at Moorfields Eye Hospital & University College London Institute of Ophthalmology, London, United Kingdom.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Foster
authors.affiliation: VAMPIRE project, School of Computing, University of Dundee, Dundee, United Kingdom.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Trucco
authors.affiliation: Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Cathie
authors.initials: C
authors.lastname: Sudlow
mesh_terms: D000328:Adult; D000368:Aged; D016208:Databases, Factual; D005260:Female; D005654:Fundus Oculi; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012164:Retinal Diseases / Q000175:diagnosis*; D012171:Retinal Vessels / Q000473:pathology*; D012984:Software