ABSTRACT
Ultraviolet light has a wide spectrum of effects on human skin depending on the wavelength. Ultraviolet light often used for therapy of psoriasis comprises of electromagnetic spectrum ranging from 200nm – 400nm. Phototherapy of psoriasis is frequently used in combination regimens to achieve higher clearance rates, longer disease-free intervals, and to reduce the patient`s cumulative radiation dose thereby lowering the carcinogenic risk. Phototherapy may be combined with topical or systemic agents. Topical agents most commonly used are anthralin, tar, vitamin D analogues and tazarotene. Among systemic agents, retinoids are the most widely used. Ultraviolet B wavelengths in the range of 300-313nm is more efficacious than conventional broad-band UV-B [Philips TL 40W/12 lamp] and causes greater remission of psoriatic lesions. 311nm narrow-band UV-B (TL-01) phototherapy is more effective and probably has no greater risk than conventional UV-B (TL-12) phototherapy in the treatment of psoriasis.