Photometric and clinical assessment of localized UVB phototherapy systems for the high-dosage treatment of stable plaque psoriasis.

BACKGROUND Ultraviolet-B (UVB) light sources are widely used for the safe and effective treatment of inflammatory skin conditions. The recent commercial introduction of fiber-coupled UVB phototherapy systems facilitates the selective exposure and treatment of localized psoriasis plaques while permitting the safe use of high-dosage treatments. OBJECTIVE In this study, the performance characteristics and clinical outcome of psoriasis treatments were assessed when using two technologically distinct sources of high-intensity, fiber-optically delivered therapeutic UVB. METHODS A pulsed, monochromatic 308 nm excimer laser and a continuous-wave, incoherent UVB light source were compared using photosensitive recording papers, images captured with a CCD camera, and on the healthy and lesional skin of ten psoriasis patients. RESULTS Beam profile analyses and minimal erythema dose (MED) test spots revealed distinct energy distribution patterns from the two devices. The Guassian-type laser beam energy distribution complicated MED determinations, whereas skin exposed to light from the incoherent UVB system developed a more uniform erythema. Both systems cleared the treated psoriasis plaques equivalently, requiring no more than two to five weeks of high-dose treatments. CONCLUSION When used at equally erythemogenic high doses, both systems produced rapid plaque clearance with minimal side effects. Unlike conventional phototherapy, localized UVB minimizes exposure to the healthy skin, making it suitable for patients with mild to moderate psoriasis, individuals with recalcitrant plaques and for the successful treatment of lesions occurring on most body sites.