Phototherapy
Phototherapy means to treat with light.
When sunlight penetrates the top layers of the skin, this ultraviolet radiation bombards the genetic material, the DNA, inside skin cells and injures it. This can cause wrinkles, aging skin, and skin cancers. However, these same damaging effects can destroy the skin cells that form psoriasis patches.
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Phototherapy for psoriasis can be administered as UVA in combination with medications or as variations of UVB radiation with or without medications. Not everyone is a candidate. For example, it may not be appropriate for patients who should avoid sunlight or those with very severe psoriasis.
UVB Therapy
Ultraviolet B (UVB) is one of the primary components of sunlight, and is the main cause of sunburn. It generally affects the outer skin layers. UVB radiation reduces the abnormally rapid skin cell growth that occurs with psoriasis.
The current standard treatments using this radiation involve exposure to a light source for a set length of time at regular schedules. Either treatment can be administered at home. Another recent option is the excimer laser that emits a precise wavelength for local areas. The treatments are:
- Broadband UVB. This has been the standard UVB phototherapy treatment in the US. Radiation is measured at 290 to 350 nm. It can be used with or without the aid of medications. It is not as potent as the treatments that use narrow-band UVB or PUVA and are not useful for chronic psoriasis.
- Narrowband UVB (NB-UVB) may be safer than other approaches, and some experts now believe it should be the first option for patients with chronic plaque psoriasis. NB-UVB is used without medications and is very potent. Whether it has any affect, however, on the disease process itself is unclear. The radiation is between 310 and 312 nm, which, theoretically, is the most beneficial component of sunlight.
- The excimer laser is proving to be more effective for treating local areas of psoriasis than many standard treatments. It gives off a precise UVB wavelength of 308 nm.
Psoralens and Ultraviolet A Radiation (PUVA)
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