Ultraviolet B is short wavelength ultraviolet light and is used for widespread thin lesions or guttate psoriasis. The dose has to be accurately controlled to give enough radiation to clear the skin without burning. Recently, "narrow waveband" ultraviolet B treatment has been developed, which increases the therapeutic effect and diminishes burning. It can be used instead of psoralen with ultraviolet A in many cases.
Ultraviolet A is long wavelength ultraviolet light, which activates psoralens in the skin. This results in diminished DNA synthesis and hence reduced epidermal turnover. The combination of psoralen with ultraviolet A is known as PUVA therapy: a dose of 8-methoxypsoralen (8MOP), 0-6-0-8 mg/kg body weight, is taken one to two hours before treatment. 5-Methoxypsoralen is also used, particularly in patients develop itching or nausea with 8MOP.
Other long term cumulative side effects of ultraviolet treatment include premature ageing of the skin, lentigenes, and eventually cutaneous malignancies. For this reason the total cumulative dose is kept below 1000 Joules.
After medical assessment treatment is given two or three times a week, with gradually increasing doses of ultraviolet A. Once the psoriasis has cleared maintenance treatments can be continued once every two or three weeks. Protective goggles are worn during treatment with ultraviolet A and dark glasses for 24 hours after each treatment. The glasses are tested for their effectiveness in screening ultraviolet A light.
A variable degree of erythema and itching may occur after treatment. Longer term side effects include a slight risk of epitheliomas developing, premature ageing of the skin, and cataract formation (which can be prevented by wearing ultraviolet A filtering goggles during and after treatment). The total cumulative dosage is carefully monitored and kept as low as possible to reduce the risk of side effects.
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Do You Suffer From the Itching and Scaling of Psoriasis? Or the Chronic Agony of Psoriatic Arthritis? If so you are not ALONE! A whopping three percent of the world’s populations suffer from either condition! An incredible 56 million working hours are lost every year by psoriasis sufferers according to the National Psoriasis Foundation.