Mechanism of action & application


Properties of optical radiation
The spectrum of optical radiation is between 100nm (UV) and 1 million nm (IR)


Optical properties of the skin
The illustration below shows the effect of optical radiation on the skin. In this context, the skin is seen as a non-homogeneous medium consisting of four layers:

  • stratum corneum & stratum spinosum = epidermis (50-150µm thick incl. stratum basale)
  • Dermis (0.8-1mm)
  • Subcutis (1-3mm)

The named layers have a different chromophore distribution, so that the reflection, transmission and scattering properties are different depending on the wavelength. The figure illustrates the respective penetration depth of the wavelength.

Wavelengths and their indications

UVB 311nm (narrow band)

  • Psoriasis
  • Plaque psoriasis
  • Vitiligo
  • Atopic dermatitis
  • Pruritus
  • Prurigo
  • Prophylaxis of polymorphic light dermatosis
  • Mycosis fungoides


UVB 311nm _ Combination therapy

  • Balneo-phototherapy (psoriasis)



  • Neurodermatitis
  • Polymorphous light eruption


UVA_ Combination therapy

  • PUVA photochemotherapy (psoriasis & vitiligo)
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