ABSTRACT
UV-A radiation leads to an immediate darkening of skin pigment due to melanin oxidation, with 40 to 60 J/cm
UV-A as the typical minimal tanning dose in clinical dermatology. Due to its long wavelength, UV-A penetrates into the dermis. A wavelength of 335 nm exerts the strongest therapeutic effect in psoriasis, but is associated with the strongest photocarcinogenic effect as well. In clinical dermatology, UV-A is most frequently used in combination with photosensitizers such as topically or systemically applied 8-methoxy-psoralene (8-MOP).
