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Br J Ophthalmol 90:75-80 doi:10.1136/bjo.2005.073643
  • Clinical science
    • Extended reports

Smoking and age related macular degeneration: the number of pack years of cigarette smoking is a major determinant of risk for both geographic atrophy and choroidal neovascularisation

  1. J C Khan1,
  2. D A Thurlby1,
  3. H Shahid1,
  4. D G Clayton1,
  5. J R W Yates1,
  6. M Bradley2,
  7. A T Moore3,
  8. A C Bird3,
  9. for the Genetic Factors in AMD Study
  1. 1Department of Medical Genetics, University of Cambridge, Cambridge, UK
  2. 2Centre for Applied Medical Statistics, Institute of Public Health, University of Cambridge, Cambridge, UK
  3. 3Institute of Ophthalmology, University College London, London, UK and Moorfields Eye Hospital, London, UK
  1. Correspondence to: Professor John Yates Department of Medical Genetics, University of Cambridge, Box 134 Addenbrooke’s Hospital, Cambridge CB2 2QQ, UK; jrwy1{at}cam.ac.uk
  • Accepted 12 September 2005

Abstract

Background/aims: There is evidence that smoking is a risk factor for age related macular degeneration (AMD). However, not all studies have demonstrated this association and several key questions about the role of smoking in AMD have still to be determined. The aim of this study was to further investigate this relation for both choroidal neovascularisation (CNV) and geographic atrophy (GA).

Methods: To investigate the relation between smoking and the risk of developing age related macular degeneration (AMD) in white people, 435 cases with end stage AMD were compared with 280 controls. All subjects had graded stereoscopic colour fundus photography and AMD was defined as the presence of GA or CNV. Smoking history was assessed using multiple parameters in a detailed questionnaire.

Results: Comparison of current and former smokers with non-smokers was consistent with smoking being a risk factor for AMD but did not reach statistical significance. There was a strong association between AMD and pack years of cigarette smoking (p = 0.002), the odds ratio increasing with the amount smoked; for subjects with more than 40 pack years of smoking the odds ratio was 2.75 (95% CI 1.22 to 6.20) compared with non-smokers. Both types of AMD showed a similar relation; smoking more than 40 pack years of cigarettes was associated with an odds ratio of 3.43 (95% CI 1.28 to 9.20) for GA and 2.49 (95% CI 1.06 to 5.82) for CNV. Stopping smoking was associated with reduced odds of AMD and the risk in those who had not smoked for over 20 years was comparable to non-smokers. The risk profile was similar for males and females. Passive smoking exposure was associated with an increased risk of AMD (OR 1.87; 95% CI 1.03 to 3.40) in non-smokers.

Conclusions: The authors have demonstrated a strong association between the risk of both GA and CNV and pack years of cigarette smoking. This provides support for a causal relation between smoking and AMD. They also show an increased risk for AMD in non-smokers exposed to passive smoking. Stopping smoking appears to reduce the risk of developing AMD.

Footnotes

  • This work was supported by a programme grant from the Medical Research Council.

  • The authors declare no competing interests in the preparation and submission of this manuscript.

  • Multicentre research ethics committee, Trent, UK and local research ethics committee approvals from each of the participating units detailed above were obtained for the study.