The sunlight that reaches us is made up of two types of harmful rays: long wave ultraviolet A (UVA) and short wave ultraviolet B (UVB). UVA rays penetrate deep into the dermis, the skin’s thickest layer.
UV light, or phototherapy, can help create repigmentation of vitiligo. It is currently considered the "gold standard" treatment when vitiligo covers 20% or more of the body. This process is slow, working from the outer edges of each patch inward, so regular Phototherapy vitiligo treatment is prescribed. Phototherapy vitiligo treatment may continue twice a week for a year or more. Phototherapy equipment has been well-studied and has been proven to be an effective treatment for vitiligo. Phototherapy treatment is generally well-tolerated in both adults and children.
For the past few years, UVB and narrow wave band UVB (311nm) have achieved a great development in clinic studies. Vitiligo patients were separately given external used cream and irradiated by UVA and UVB 311nm. The results show that the 311nm UVB treatment effect is same with the UVA therapy. UVB therapy have a less phototoxicity and restore pigment evenly, It also can use the pregnant women. at the same time scholars found that catalase level is low in both epidermis involved vitiligo or not involved vitiligo. When amount of H₂O₂ increase at the epidermis layer of skin, it will have toxic effect to melancytes. We also found that the involved skin calcium losing balance. However UVB irradiation can active the pseudo catalase it can decompose H₂O₂ as H₂O and O₂.
Some of scholars applied the external using pseudo catalase and cacl₂, twice a day, and combine UVB 311nm irradiation, the simple dosage amount is 0.15-0.3J/cm², twice a week, as a result most of the patients vitiligo stop to develop. At the same time some scholars found that human keratinocytes cultured after the irradiated by UVB, it can release basic fibroblast growth factors and facilitate the secretion oof the KC secretion of skin pigment–1, it can induce the roliferation and differentiation of melancytes.