Ultraviolet Light in Human Health, Diseases and Environment

Annalisa Patrizi, Beatrice Raone, Giulia Maria Ravaioli, Patrizi, Annalisa, Raone, Beatrice, Ravaioli, Giulia Maria

Atopic Dermatitis (AD), a common skin disease, can occur in patients of all age, gender and ethnicity. It is an inflammatory affection, characterized by chronic and highly debilitating behavior. First-line interventions against AD include environmental measures and topical emollients, corticosteroids or calcineurin inhibitors. When these measures are not sufficient, phototherapy represents an efficient second-line option of treatment; it can be administered on its own, or in the most severe cases combined with systemic medicaments such as corticosteroids.Different types of light therapy, including photochemotherapy, have been tested in the past and in recent years for AD: in particular, ultraviolet A1 (UVA1) and narrow band ultraviolet B (NB-UVB) have been reported in the literature as the most effective resources, respectively for acute and chronic AD. However, to date, no guidelines have been realized concerning the use of phototherapy for AD, as no light form has been defined superior to the others. The most reliable protocols and dosimetry are standardized within the American Academy of Dermatology (AAD) psoriasis guidelines.In adults and children over 12 years (8 years for NB-UVB) phototherapy is recommended with strength B and level of evidence II (excluding home phototherapy, which is recommended with strength C and level of evidence III). It is usually safe and well tolerated; however its short- and long-term adverse effects are the same as those observed when light therapy is performed for other pathologic conditions. Erythema and photodamage are in particular quite frequent; moreover it has not been clarified whether UV radiation may induce neoplastic cellular transformation. For all these reasons, the use of phototherapy must be chosen only after a comprehensive and careful evaluation of the patient's features and compliance, as well as of the limitations of the procedure due to costs and availability.