Pterygium and conjunctival ultraviolet autofluorescence in young Australian adults: the Raine study

BACKGROUND: Sun exposure is associated with several ophthalmic diseases, including pterygium which may develop in adolescence. This study reports the prevalence of pterygium and its associations in a large cohort of young Australian adults. Conjunctival ultraviolet autofluorescence, a biomarker of ocular sun exposure, has recently been characterized in some Australian populations.

DESIGN: Cross-sectional population-based study.

PARTICIPANTS: One thousand three hundred forty-four subjects aged 18-22 years in the Western Australian Pregnancy Cohort (Raine) Study.

METHODS: Standardized colour and ultraviolet autofluorescence photographs of the nasal and temporal conjunctiva were taken, and assessed for presence of pterygium and area of autofluorescence. Sun exposure and protective factors were assessed by structured questionnaire.

MAIN OUTCOME MEASURES: Area of conjunctival ultraviolet autofluorescence in square millimetre (mm²) and presence of pterygium.

RESULTS: Median total conjunctival autofluorescence was 44.2 mm² (interquartile range 20.2-69.8 mm²). Median conjunctival autofluorescence was higher in nasal than in temporal quadrants (23.8 mm² vs. 18.9 mm², P < 0.001), but did not differ according to age or gender. Higher body mass index was associated with lower levels of autofluorescence. Total autofluorescence increased with increasing time spent outdoors. Prevalence of pterygium was 1.2% (95% confidence interval 0.6-1.8%), and was associated with male gender (odds ratio 6.71, P = 0.012). Participants with pterygium had significantly more conjunctival autofluorescence than those without (median 73.4 mm² vs. 44.0 mm², P = 0.001).

CONCLUSIONS: Conjunctival ultraviolet autofluorescence is associated with increased time spent outdoors, and increased prevalence of pterygium. The association of this biomarker with other ophthalmohelioses, including cataract, ocular surface squamous neoplasia and eyelid malignancy, has yet to be determined.