Ultraviolet light exposure as a risk factor for ocular melanoma in Queensland, Australia

Abstract

The state of Queensland, Australia, has one of the highest incidences of cutaneous melanoma in the world; this has been linked to the high sun exposure of the mainly Caucasian population. The role of sun exposure in the development of ocular melanoma (melanoma of the conjunctiva, iris, ciliary body or choroid) remains unclear. A case-control study involving 125 patients with ocular melanoma treated between 1972 and 1996, and 375 age- and sex-matched controls (three for each patient) was performed. A standardised telephone questionnaire examining ultraviolet exposure and other potential risk factors was administered. Cumulative lifetime ocular ultraviolet B (UV-B) exposure was assessed using the Melbourne Visual Impairment Project instrument. Risk factors identified include personal history of melanoma of the skin (odds ratio [OR] 2.42, 95% confidence interval [CI] 0.88, 6.62) or other skin cancers (OR 1.52, CI 0.99, 2.35), and family history of ocu-lar melanoma (OR 6.89, CI 0.70, 67.38). Protective factors included olive or black skin (OR 0.72, CI 0.40, 1.31), brown iris colour (OR 0.89, CI 0.51, 1.54), high resistance to sunburn (OR 0.58, CI 0.26, 1.31), and wearing prescription glasses (OR 0.78, CI 0.48, 1.25). Sunglass wearing was not found to be protective. Cumulative lifetime ocular UV-B exposure was not found to be a risk factor for ocular melanoma. However, there were too few cases of conjunctival and iris melanoma for these to be analysed as separate sub-groups.