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Epidemiology
Research
The EPIC-Norfolk Eye Study: rationale, methods and a cross-sectional analysis of visual impairment in a population-based cohort
  1. Anthony P Khawaja1,
  2. Michelle P Y Chan2,
  3. Shabina Hayat1,
  4. David C Broadway3,
  5. Robert Luben1,
  6. David F Garway-Heath4,
  7. Justin C Sherwin1,
  8. Jennifer L Y Yip1,
  9. Nichola Dalzell1,
  10. Nicholas J Wareham5,
  11. Kay-Tee Khaw1,
  12. Paul J Foster2,4
  1. 1Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge School of Clinical Medicine, Cambridge, UK
  2. 2Division of Genetics and Epidemiology, UCL Institute of Ophthalmology, London, UK
  3. 3Department of Ophthalmology, Norfolk & Norwich University Hospital, Norwich, UK
  4. 4NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundations Trust and UCL Institute of Ophthalmology, London, UK
  5. 5MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
  1. Correspondence to Professor Paul J Foster; p.foster{at}ucl.ac.uk

Abstract

Objectives To summarise the methods of the European Prospective Investigation of Cancer (EPIC)-Norfolk Eye Study, and to present data on the prevalence of visual impairment and associations with visual impairment in the participants.

Design A population-based cross-sectional study nested within an on-going prospective cohort study (EPIC).

Setting East England population (the city of Norwich and its surrounding small towns and rural areas).

Participants A total of 8623 participants aged 48–92 years attended the Eye Study and underwent assessment of visual acuity, autorefraction, biometry, tonometry, corneal biomechanical measures, scanning laser polarimetry, confocal scanning laser ophthalmoscopy, fundal photography and automated perimetry.

Outcome measures Visual impairment was defined according to the WHO classification and the UK driving standard, and was based on presenting visual acuity. Summary measures of other ophthalmic measurements are also presented.

Results The prevalence (95% CI) of WHO-defined moderate-to-severe visual impairment and blindness was 0.74% (0.55% to 0.92%). The prevalence (95% CI) of presenting visual acuity worse than the UK driving standard was 5.87% (5.38% to 6.37%). Older age was significantly associated with visual impairment or blindness (p<0.001). Presenting visual acuity worse than UK driving standard was associated with older age (p<0.001), female sex (p=0.005) and lower educational level (p=0.022).

Conclusions The prevalence of blindness and visual impairment in this selected population was low. Visual impairment was more likely in older participants, women and those with a lower educational level.

  • EPIDEMIOLOGY
  • OPHTHALMOLOGY

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: http://creativecommons.org/licenses/by-nc/2.0/ and http://creativecommons.org/licenses/by-nc/2.0/legalcode.

https://doi.org/10.1136/bmjopen-2013-002684

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