An epidemiological perspective of ultraviolet exposure--public health concerns

Over the last 30 years, many countries have developed strong sun protection programs, spurred on by rapidly increasing skin cancer incidence and concerns about stratospheric ozone depletion. More recently, considerable concern has arisen about widespread vitamin D insufficiency, creating a "sun exposure dilemma," since in most regions vitamin D predominantly derives from endogenous synthesis in the skin initiated by exposure to ultraviolet (UV) radiation. Little attention has been paid to whether a similar dilemma exists for UV-related eye conditions.For the eyes, to our current knowledge, exposure to UV radiation has only adverse effects. There is strong evidence that acute high dose exposure to UV radiation causes photokeratitis and photoconjunctivitis, while even low dose chronic exposure to UV radiation is a risk factor for cataract, pterygium, and squamous cell carcinoma of the cornea and conjunctiva. There is weaker evidence in relation to other conditions, including ocular melanoma and age-related macular degeneration. Ultraviolet radiation-related eye diseases are common, disabling, and cause a considerable disease burden worldwide.The "correct" public health message for optimal sun exposure is not clear cut, with too many variables-ambient UV radiation, personal skin type, age, weight, clothing habits, medication, and others-for a blanket sun safety message. In addition, there remain many unknowns, including strong evidence supporting or refuting the very many proposed health benefits of vitamin D. More evidence is required to define disease burdens for UV-induced eye diseases, to evaluate the decrease in disease burden from sun protective measures and to elucidate any beneficial effects of exposure of the eye to UV radiation, to provide appropriate advice to the public.