XeCl excimer laser coronary angioplasty: a convergence of favourable factors

Efficacy of the 308-nm excimer laser for treatment of psoriasis: results of a multicenter study

OBJECTIVE

Our purpose was to demonstrate the efficacy of the 308-nm excimer laser for treatment of psoriasis.

METHODS

This study was a multicenter open trial from 5 dermatology practices (one university-based and 4 private practices). Up to 30 patients per center with stable mild to moderate plaque-type psoriasis constituted the study population. Patients received 308-nm ultraviolet B doses to affected areas. The initial dose was based on multiples of a predetermined minimal erythema dose. Subsequent doses were based on the response to treatment. Treatments were scheduled twice weekly for a total of 10 treatments. The main outcome measure was 75% clearing of the target plaque. Time to clearing was analyzed by Kaplan-Meier methods, accounting for truncated observations.

RESULTS

One hundred twenty-four patients were enrolled in the study, and 80 completed the entire protocol. The most common reason for exiting from the study was noncompliance. Of the patients who met the protocol requirements of 10 treatments or clearing, 72% (66/92) achieved at least 75% clearing in an average of 6.2 treatments. Eighty-four percent of patients (95% confidence interval [CI], 79%-87%) reached improvement of 75% or better after 10 or fewer treatments. Fifty percent of patients (95% CI, 35%-61%) reached improvement of 90% or better after 10 or fewer treatments. Common side effects included erythema, blisters, hyperpigmentation, and erosions, but they were well tolerated.

CONCLUSIONS

Monochromatic 308-nm excimer laser treatment appears to be effective and safe for psoriasis. It requires fewer patient visits than conventional phototherapy, and, unlike those treatments, the laser targets only the affected areas of the skin, sparing the surrounding uninvolved skin.

Mutagenic effects of the Excimer laser using a fibroblast transformation assay

For over 10 years fiber-guided laser systems have been used in arthroscopic surgery. The possibility of a mutagenic risk by the use of lasers has not been sufficiently repudiated, especially for the Excimer laser at a wavelength of 308 nm, which is close to the absorption spectrum of DNA. The aim of this study therefore was to approximate the mutagenic risk of UV-laser wavelengths using an in vitro transformation assay. BALB/3T3 fibroblasts were irradiated with Excimer laser wavelengths of 248 nm and 308 nm. The resulting transformation rates were compared to those of untreated cells and to cells that were subjected to an x-ray dose of 1 Gy. Pulse energy, frequency, and irradiation time were varied over a wide range, from sublethal fluences to total cell death. Furthermore, the effect of repeated irradiation (split-dose) was analyzed. The results for the 248 nm irradiation showed a highly significant transformation rate (P < 10(-9)). In contrast, results for the 308 nm irradiation were not at all significant (P < .18). The transformation rate of cells that were treated with x-rays was increased exponentially compared with the controls. Although an increased transformation rate was found after 248 nm irradiation, that of the wavelength 308 nm was not enhanced. The study therefore shows that the use of the Excimer wavelength 308 nm in arthroscopic procedures does not imply a specific mutagenic risk.