Ultraviolet Light Therapy

Ultraviolet (UV) light therapy has been use for many years to treat such varied conditions as psoriasis, vitiligo, atopic dermatatitis, and pruritis(itching) At North Valley Dermatology, we have a broad range of therapeutic options regarding the use of ultraviolet light in the treatment of skin conditions. Below is a discussion of UV light therapy in general and the options for treatment available at North Valley Dermatology.

What is Ultraviolet Radiation?

Description of UVA and UVB Radiation. The two phototherapy treatments for chronic cases of psoriasis employ ultraviolet B (UVB) or ultraviolet A (UVA) radiation. Both UVA and UVB radiation are components of sunlight.

• UVB is the primary agent in sunbuming and primarily affects the outer skin layers.
  
  
• UVA penetrates more deeply and efficiently and is probably more responsible for skin wrinkling.

When sunlight penetrates the top layers of the skin, ultraviolet radiation bombards the genetic material (the DNA), inside the skin cells causing injury. It also impairs immune function in the skin. Such effects are the cause of wrinkles, aging skin disorders, and skin cancers. These same damaging effects, however, can also destroy the skin cells that form psoriasis patches.

Although both UVA and UVB can destroy psoriasis skin cells when used in phototherapies, there are some differences:

• UVB is about 1,000 times more powerful than UVA in producing sunburn. Mild pink skin (erythema) caused by UVB, in fact, can be effective against psoriasis. The same skin tone caused by UVA atone, however, does little good.
  
  
• UVB may be used alone while UVA requires a photosensitizing medication to be effective. However, this combination UVA treatment, called PUVA, is generally much more potent than standard UVB therapies.
  
  
• PUVA poses a higher risk for skin cancers, including melanoma, than UVB.
  
  
• UVA units are available for home tanning and in tanning salons, although experts rarely recommend such treatments because of the cancer risks from over-exposure and the lack of benefit without medication.

At North Valley Dermatology center, we have chose to treat with primarily UVB light. We have recently purchased a light unit capable of both broad band and narrow band UVB therapy.

Broadband Ultraviolet B (UVB) Radiation

Broad spectrum UVB is radiation measured at 290 to 350 nm and has been the standard UVB phototherapy treatment. (UVB radiation below measurements of 300 nm is toxic but not effective, while radiation above 300 nm is more therapeutic.) Broad spectrum UVB phototherapy may be administered as follows:

• Using UVB radiation alone.
• UVB treatment with coal tar (the Goeckerman regimen).
• UVB with anthralin (the Ingram regimen).

These are effective treatments for local or widespread psoriasis that cannot be managed with topical preparations alone. The procedure differs depending on whether it is used with medication or without. The use of retinoids, such as a tazarotene gel or oral acttretrin, may increase its effectiveness.
Broadband UVB Procedures Used Without Medication. When used without medication (known as selective ultraviolet phototherapy) UVB treatment generally is administered as follows:

• UVB therapy usually requires about 20 to 40 treatments (about three per week).
  
  
• Full results take about three to six weeks.
  
  
• Maintenance treatment is given twice weekly for one to two months and then once a
  week for about four months. This is generally effective in preventing relapse.

Broadband UVB Procedures Used With Medication. When combined with coal tar or anthralin, UVB may be administered as follows:

• This combined therapy may require applying the medicine at night and being seen in the
  morning for light therapy.
  
  
• Treatments may need to be administered daily or every other day for two to four weeks.
  

Side Effects of UVB. It has not been thought that UVB treatments pose any risk for skin cancers except on male genitalia. One study reported, however, that melanoma developed in human tissue exposed to UVB radiation. Furthermore, a 1999 study suggested that UVB treatments probably cause up to two nonmelanoma skin cancers per 100 patients. Some experts postulate, on the other hand, that UVB therapy may actually have protective properties, since doses are generally low and it causes the skin to thicken but does not bum the skin, a primary trigger for skin cancer.

Narrow Band Ultraviolet B (NB-UVB)

Narrow band (NB) UVB radiation uses fluorescent lighting that emits radiation in a specific range between 310 and 312 nm, which, theoretically is the most beneficial component of sunlight. It is the primary UVB treatment in Europe and is gaining wide acceptance in the US. The following are the advantages of NB-UVB:

• Exposure times are shorter but of higher intensity than with broadband UVB.
  
  
• It is nearly as potent as PUVA therapy and is most likely safer.
  
  
• It is very efficient in reducing T-cells in the skin (the immune factors responsible for psoriasis).
  
  
• The course of treatment is shorter.

One expert suggests the following treatment schedule:

• Treatments are performed three times a week to start.
  
  
• Improvement typically occurs after 10 to 12 treatments.
  
  
• Thereafter, maintenance treatments are given once a week.

People Who Should Avoid Phototherapy:

• Patients who are sensitive to sunlight.
  
  
• Possibly people with HIV infection. One small study suggested that exposure to ultraviolet radiation may worsen HIV. Antiviral therapy can help protect such patients who need phototherapy. (This study may also have implications for sun exposure in HIV-positive people.)