title: The association between pterygium and conjunctival ultraviolet autofluorescence: the Norfolk Island Eye Study.
abstract: OBJECTIVE
  To investigate the association between conjunctival ultraviolet autofluorescence (UVAF), a biomarker of ocular ultraviolet radiation (UVR) exposure, and prevalent pterygium.
  
  
  METHODS
  We conducted a cross-sectional study on Norfolk Island, South Pacific. All permanent residents aged ≥15 were invited to participate. Participants completed a sun exposure questionnaire and underwent autorefraction and slit lamp biomicroscope examination. Area of conjunctival UVAF (sum of temporal/nasal area in right and left eyes) was determined using computerized methods. Multivariate logistic and linear regression models were used to estimate the associations with pterygia and UVAF, respectively.
  
  
  RESULTS
  Of 641 participants, 70 people (10.9%) had pterygium in one or both eyes, and prevalence was higher in males (15.0% versus 7.7%, p = 0.003). Significant independent associations with pterygium in any eye were UVAF (per 10 mm(2)) [odds ratio (OR) 1.16, 95% confidence interval (CI) 1.16-1.28, p = 0.002], tanning skin phenotype (OR 2.17, 1.20-3.92, p = 0.010) and spending more than three-quarters of the day outside (OR 2.22, 1.20-4.09, p = 0.011). Increasing quartile of UVAF was associated with increased risk of pterygium following adjustment of age, sex and time outdoors (p(Trend) = 0.002). Independent associations with increasing UVAF (per 10 mm(2)) were decreasing age, time outdoors, skin type and male gender (all p < 0.001). UVAF area correlated well with the duration of outdoor activity (p(Trend) < 0.001).
  
  
  CONCLUSIONS
  Pterygium occurs in approximately one-tenth of Norfolk Islanders. Increasing conjunctival UVAF is associated with prevalent pterygia, confirming earlier epidemiological, laboratory and ray-tracing studies that pterygia are associated with UVR. Protection from the sun should be encouraged to reduce the prevalence of pterygium in the community.
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Department of Ophthalmology, Melbourne, Vic., Australia.
authors.forename: Justin C
authors.initials: JC
authors.lastname: Sherwin
authors.forename: Alex W
authors.initials: AW
authors.lastname: Hewitt
authors.forename: Lisa S
authors.initials: LS
authors.lastname: Kearns
authors.forename: Lyn R
authors.initials: LR
authors.lastname: Griffiths
authors.forename: David A
authors.initials: DA
authors.lastname: Mackey
authors.forename: Minas T
authors.initials: MT
authors.lastname: Coroneo
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D003228:Conjunctiva / Q000473:pathology / Q000528:radiation effects*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008542:Melanesia / Q000453:epidemiology; D008875:Middle Aged; D016017:Odds Ratio; D061848:Optical Imaging / Q000379:methods*; D015995:Prevalence; D011625:Pterygium / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D012189:Retrospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D013472:Sunlight / Q000009:adverse effects; D011795:Surveys and Questionnaires; D014466:Ultraviolet Rays / Q000009:adverse effects; D055815:Young Adult