What is Phototherapy?
Phototherapy is the use of ultraviolet light produced by special fluorescent tubes to treat a number of skin diseases. The most commonly treated conditions are psoriasis and eczema. There are some less frequently occurring diseases such as widespread granuloma annulare, aquagenic urticaria, mycosis fungoides which may also respond to phototherapy.
The sun produces ultraviolet radiation. All radiation produced by the sun is characterized by its wavelength. Ultraviolet radiation has wavelengths between 100-400 nanometres. Filtration by the earth’s atmosphere and ozone means that on the earth’s surface we are exposed only to wavelengths between 290-400nm. Most people troubled with psoriasis and eczema find that their disease is better in the summer when many people spend more time outdoors in the sun. Sunlight and phototherapy only work where the light reaches.
The two most common forms of phototherapy used clinically to treat the trunk and limbs are Narrow Band Ultraviolet B treatment (NBUVB), and Psoralens plus Ultraviolet A (PUVA). The difference between the two forms of treatment is the wavelength of radiation used. In NBUVB the wavelengths are 310-313 nanometres. The UVA lamps produce wavelengths between 340-370 nanometres.
In PUVA a medication, which makes the skin more reactive to the ultraviolet rays, must be taken about two hours before exposure. NBUVB is becoming the more popular form of treatment because there is no necessity to take a medication prior to treatment nor take special precautions to protect the skin for the 24 hours after treatment. There are specialized machines available for treating localized areas such as hands and feet with NBUVB and PUVA, and also a wand for administering UVA to problems in the mouth.
It is important to realize that the treatment given in the phototherapy box adds with all the other sun exposure you have had to increase the aging of the skin and the risk of developing skin cancers. For this reason, we try to limit the number of courses of treatment. Individuals who frequently expose their skin to ultraviolet light in solariums also increase the rate of aging of their skin and risk of skin cancer.
Who can be treated with phototherapy?
- With widespread skin disease which is difficult to treat with creams and ointments.
- Whose referring doctor and the phototherapy clinic doctor do not find any medical reason why they should not be exposed to ultraviolet light.
- Who can attend regularly 3 or 4 times a week for 6 to 8 weeks for their course of treatment.
- Can stand in a small box for the time needed to deliver the treatment.
- Understand the risks and benefits of the treatment and wish to proceed.
Who cannot be treated with phototherapy?
- Past history of malignant melanoma.
- Inherited disorders which them more likely to develop skin cancers and melanomas.
- Severely sun damaged skin with a past history of many skin cancers or very active moles.
- Are taking immunosuppressive therapy, many of which may also increase the risk of skin cancers. Patients who have had organ transplants and have developed graft versus host disease (GVHD) are exceptions to this.
- Children aged less than 10 years.
What results can I expect from undergoing a course of phototherapy?
Most patients who are able to attend regularly for treatment will find that their psoriasis or eczema is 70% improved after 20-30 treatments.
How long does the beneficial effect of phototherapy last?
There is no way of predicting. Sometimes remission lasts for 12 or 18 months, sometimes only 12 or 18 weeks.
What side effects occur?
- During the course of the treatment although every effort is made to avoid a burn, they do sometimes occur. Depending upon the severity of the burn – it may be necessary to miss a treatment or reduce the rate of dosage increase.
- Just as sun exposure can precipitate cold sores, so can light therapy – extra protection with zinc or other opaque sunscreens on the usually affected area may avoid this problem.
- Some people find their skin becomes drier during treatment, moisturising the skin and not using too much soap in the shower reduces this dryness.
- When the psoriasis or eczema gets better there is a darkening of the skin where the skin problem was. This darkening is temporary but may take some weeks or even months to go away.
- Long-term frequent courses of phototherapy do increase the aging of the skin and add to the risk of developing skin cancers.
If your doctor recommends phototherapy to treat your skin problem, he/she will discuss the treatment in more detail. Before commencing a course of treatment the phototherapy nurse/technician will go through the treatment protocol with you and ask you to sign a consent form.