308-nm Excimer Laser for the Treatment of Psoriasis

Abstract

UV-B PHOTOTHERAPY is a well-established form of psoriasis treatment that generally requires 25 to 30 treatments to produce clearing. Supraerythemogenic fluences of UV-B and psoralen–UV-A are known to result in faster clearing of psoriasis^1,2; however, the limiting factor for the use of such high fluences lies with the intolerance of the uninvolved surrounding skin since psoriatic lesions can often withstand much higher UV exposures. Furthermore, units capable of delivering such large fluences selectively to the psoriatic plaques within a reasonable time do not exist. Recently, narrowband UV-B phototherapy has been shown^3-5 to be effective in the treatment of psoriasis. Although long-term results are not firmly established, some evidence⁶ suggests that this new modality might prove to be less carcinogenic. Presumably, this narrow wavelength is not very different biologically from the 308-nm radiation generated by the XeCl excimer laser. Indeed, preliminary work⁷ has established some efficacy for excimer laser–generated 308-nm radiation in the treatment of psoriasis. This study was designed to determine the dose-response relationship of excimer laser–generated 308-nm UV-B radiation, which is selectively directed toward psoriatic plaques, with regard to efficacy of clearing and length of remission.