Ultraviolet‐action Spectrum and Evaluation of Ultraviolet Lamps for Psoriasis Healing

For some time there has been disagreement on whether ultraviolet (UV) radiation can heal psoriasis.'-Recent studies have, however, clearly shown the psoriasis-healing effect of UV radiation alone, psoralen plus UV radiation, and coal tar plus UV radiation.^-'' From these results and from additional experiments presented in this review, action spectra for psoriasis healing can be drawn. With these action spectra and the spectral intensity distributions ot UV lamps, light boxes, or solaria, it is possible to calculate their healing effect with the different types of UV treatment. A quality norm for solaria is proposed. Narrow wavelength bands in the region of 313, 334, 365, and 405 nm were isolated from high-intensity, high-pressure mercury lamps using different filter combinations.' Such a lamp filtered with quartz glass only was used to get a broad spectrum band in the UV 250400 nm, with peaks at the mercury lines. The 254 nm mercury line was isolated from a low-pressure mercury lamp flushed with nitrogen gas. In 25 individuals with severe psoriasis, round areas 22 mm in diameter were mapped within homogenous psoriasis plaques. These areas were irradiated with different radiation doses from the different UV bands (Table 1). The areas were either pretreated with trioxsalen (4,5,8-trimethyl-psoralen 0.05% in ethanol 95%) or coal tar (spiritus carbonis detergens 20%, Pharmaconomia Suecia ed. IV) or untreated before the irradiation. To sensitize, we spread about 10/x I/cm ^ of psoralen or coal tar solution evenly over the test area 1 hour before the irradiation. The 313-, 365-, and 405-nm bands were given to all 25 individuals with psoriasis, whereas the 254and 334-nm bands were given to 6 and 4 individuals, respectively. The areas had equal treatment daily 5