Effect of Narrow-Band Ultraviolet B Therapy of Psoriasis Vulgaris on Skin Directional Reflectance, Skin Density and Epidermal Thickness

Psoriasis is an inflammatory dermatosis manifested by the appearance of brown-red papules on the body, covered with silver scales. One of the most common and effective treatments for psoriasis is narrow-band UVB phototherapy. Narrow-band UVB has a wavelength of 311 nm, which results in shallow skin penetration, is absorbed only by the epidermis and the superficial layers of the dermis. The aim of the study was to assess the effect of narrow-band UVB 311 nm phototherapy on skin covered with psoriatic scales and without psoriatic lesions in patients with psoriasis vulgaris on the total directional hemispherical reflectance (DHR) of the skin, skin density and epidermis thickness. For this purpose, a 410 Solar DHR reflectometer and high-frequency ultrasonography DUB SkinScanner were used. A total of 48 volunteers were enrolled. There was a difference in the reflectance of skin without psoriatic scales and psoriatic skin. Depending on the wavelength range, the skin was characterized by different reflectance values. During the course of phototherapy, the reflectance values decreased, both in the psoriatic skin and skin without psoriatic scales. After the phototherapy, the epidermis thickness and SLEB layer decreased and skin density increased in the area with psoriatic plaque. The density of the skin without psoriasis after a series of 20 irradiations increased, while the thickness of the epidermis did not change.