The Excimer Laser for Psoriasis: A Review of Safety and Efficacy

affecting 2.6 percent of the US population. It is debilitating both physically and mentally, and there is always a need to develop treatment options with better success rates, not only acutely, but long-term. Despite the wide range of treatment options available, UVB phototherapy remains one of the safest therapeutic modalities for psoriasis. The latest development in UVB phototherapy is the excimer laser, a novel therapeutic option where a beam of coherent light with a wavelength of 308nm is transmitted through a handheld articulated arm. The device uses a spot diameter of 14 to 30mm, allowing targeted therapy to a small area on the skin and thus the ability to spare healthy skin from exposure to UV radiation. In addition, since psoriatic skin can usually tolerate a higher dose of UVB than unaffected skin can, treatment can be conducted at multiples of the minimal erythema dose (MED). This aggressive “supraerythemogenic” therapy greatly enhances the efficacy of UVB phototherapy and thereby results in fewer required sessions and a lower accumulated dose of UVB. Although the mechanism of action of targeted phototherapy appears to be similar to that of other modes of UV-based therapy, namely, induction of Tcell apoptosis, suppression of DNA synthesis, and generation of prostaglandins and cytokines, reports have demonstrated that 308nm excimer laser is more effective than NB-UVB. Proposed mechanisms for this enhanced efficacy include deeper penetration of the skin and more potent capacity to induce T-cell apoptosis. Because of this, targeted phototherapy with excimer laser appears to induce longer remisThe Excimer Laser for Psoriasis: A Review of Safety and Efficacy