Psoriasis, is a chronic, recurrent, inflammatory and systemic skin disease caused by genetic and environmental effects. Psoriasis in addition to the skin symptoms, there will also be cardiovascular, metabolic, digestive and malignant tumors and other multi-system diseases. Although it is not infectious, it mainly hurts the skin and has a great impact on the appearance, which brings great physical and psychological burden to the patients and seriously affects the quality of life.
So, how does ultraviolet phototherapy treat psoriasis?
Topical drugs are the main treatment for mild to moderate psoriasis. The treatment of topical drugs depends on the patient's age, history, type of psoriasis, course of disease and lesions.
Commonly used drugs are glucocorticoids, vitamin D3 derivatives, retinoic acid and so on. Systemic use of oral drugs or biologics such as methotrexate, cyclosporine and retinoic acid is recommended for patients with scalp psoriasis accompanied by moderate to severe lesions.
Ultraviolet phototherapy is a more recommended treatment for psoriasis in addition to drugs. Phototherapy mainly induces the apoptosis of T cells in psoriatic lesions, thus inhibiting the overactivated immune system and promoting the regression of lesions.
It mainly includes BB-UVB(>280~320nm), NB-UVB(311±2nm), PUVA(oral, medicinal bath and local) and other treatments.
The curative effect of NB-UVB was better than BB-UVB and weaker than PUVA in UV treatment of psoriasis. However, NB-UVB is the most commonly used ultraviolet treatment with high safety and convenient use.
Topical UV treatment is recommended when the skin area is less than 5% of the total body surface area.
When the skin area is greater than 5% of the body surface area, systemic UV treatment is recommended.
In the treatment of psoriasis, the main effective band of UVB is in the range of 308~312nm. The effective band of NB-UVB(311±2nm) in the treatment of psoriasis is more pure than that of BB-UVB(280~320nm), and the effect is better, close to the effect of PUVA, and reduces the erythematous reaction caused by the ineffective band. Good safety, no association with skin cancer was found. At present, NB-UVB is the most popular clinical application in the treatment of psoriasis.
