The excimer laser is a type of laser that produces monochromatic radiations and emits wavelengths in the spectrum of ultraviolet light.

The excimer laser with a wavelengths of 308 nm is used for the therapy of various dermatological disorders such as: psoriasis, vitiligo, atopic dermatitis, alopecia areata. The wavelength of 308 nm is very close to that of 311 nm used by the narrow-band UVB phototherapy, which is successfully used in the treatment of these cutaneous diseases.

The radiations of the UVB spectrum have immunosuppresive effects by inducing the apoptosis of T cells and are immunomodulators, thus they are effective in the treatment of immune disorders.

Clinical trials are being conducted on larger and larger groups of patients treated with laser excimer. A higher efficiency of laser excimer over narrow-band UVB phototherapy has already been proven on small groups of patients, which obtained clinical improvement and remision of their dermatological disorder. The advantages of laser excimer therapy also include a decrease in the number of sesions needed in order to achieve clinical results, a decrease of the cumulative dose and sparring of the healthy

tissues. Immediate adverse effects are dose-dependent and long term ones are not yet known.