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Original article
Reliability and validity of conjunctival ultraviolet autofluorescence measurement
  1. Justin C Sherwin1,2,
  2. Charlotte M McKnight3,
  3. Alex W Hewitt1,
  4. Lyn R Griffiths4,
  5. Minas T Coroneo5,
  6. David A Mackey1,3,6
  1. 1Department of Ophthalmology, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Victoria, Australia
  2. 2Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Cambridge, UK
  3. 3Centre for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Australia
  4. 4Genomics Research Centre, Griffith Health Institute, Griffith University, Southport, Queensland, Australia
  5. 5Department of Ophthalmology, University of New South Wales, Sydney, Australia
  6. 6Department of Ophthalmology, Royal Hobart Hospital, University of Tasmania, Hobart, Tasmania, Australia
  1. Correspondence to Professor David A Mackey, Lions Eye Institute, Centre for Ophthalmology and Visual Science, University of Western Australia, 2 Verdun St, Nedlands 6009 WA, Australia; d.mackey{at}utas.edu.au

Abstract

Background Conjunctival ultraviolet autofluorescence (UVAF) photography was developed to detect and characterise pre-clinical sunlight-induced UV damage. The reliability of this measurement and its relationship to outdoor activity are currently unknown.

Methods 599 people aged 16–85 years in the cross-sectional Norfolk Island Eye Study were included in the validation study. 196 UVAF individual photographs (49 people) and 60 UVAF photographs (15 people) of Norfolk Island Eye Study participants were used for intra- and inter-observer reliability assessment, respectively. Conjunctival UVAF was measured using UV photography. UVAF area was calculated using computerised methods by one grader on two occasions (intra-observer analysis) or two graders (inter-observer analysis). Outdoor activity category, during summer and winter separately, was determined with a UV questionnaire. Total UVAF equalled the area measured in four conjunctival areas (nasal/temporal conjunctiva of right and left eyes).

Results Intra-observer (ρ_c=0.988, 95% CI 0.967 to 0.996, p<0.001), and inter-observer concordance correlation coefficients (ρ_c=0.924, 95% CI 0.870 to 0.956, p<0.001) of total UVAF exceeded 0.900. When grouped according to 10 mm2 total UVAF increments, intra- and inter-observer reliability was very good (κ=0.81) and good (κ=0.71), respectively. Increasing time outdoors was strongly with increasing total UVAF in summer and winter (ptrend <0.001).

Conclusion Intra- and inter-observer reliability of conjunctival UVAF is high. In this population, UVAF correlates strongly with the authors' survey-based assessment of time spent outdoors.

  • Epidemiology
  • outdoor activity
  • reliability
  • validity
  • ultraviolet radiation
  • public health
  • drugs
  • glaucoma
  • inflammation
  • intraocular pressure
  • ocular surface
  • genetics
  • cosmesis
  • cornea
  • conjunctiva
  • physiology
  • angle
  • lens and zonules
  • anterior chamber
  • stem cells

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Footnotes

  • Funding Financial support was provided by the Royal Victorian Eye and Ear Hospital research committee and the Peggy and Leslie Cranbourne Foundation. Centre for Eye Research Australia receives operational infrastructure support from the Victorian government. We wish to thank the community of Norfolk Island for participation in this research and for welcoming us into their community.

  • Competing interests The authors indicate no financial conflict of interest. DAM is a recipient of the Pfizer Australia Senior Research Fellowship. MTC discloses that he is the inventor of US Patent 7 217 289: Treatment of photic disturbances in the eye, US Patent 7 846 467: Ocular scaffold for stem cell cultivation and methods of use, US patent application 20060204474: Treatment of epithelial layer lesions, US patent application 20050287115: Treatment of ocular lesions; is a consultant to Allergan, Inc. in the area of medical treatment of pterygium and dry eye and has received research funds and travel support; receives royalties from Eagle Vision Inc. in relation to a dry eye product; and has been a consultant to Johnson and Johnson Vision Care Inc and has received research funds and travel support.

  • Ethics approval The ethics approval was provided by the human research and ethics committees of Griffith University, Royal Victorian Eye and Ear Hospital in Melbourne.

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

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