Phototherapy – Light Therapy
Phototherapy involves exposing the skin to visible ultraviolet light on a regular basis and under medical supervision. Treatments are performed in the phototherapy unit, and consistency is the key to success.
UVB and UVA phototherapies
UVB phototherapy (ultraviolet radiation Β, 290-320 nm)
Present in natural sunlight, ultraviolet B (UVB) is an effective treatment for psoriasis, it penetrates the skin and slows the growth of affected psoriatic cells. Treatment involves exposing the skin with psoriasis to an artificial UVB light source for a set length of time on a regular schedule.
There are two types of UVB, broad band and narrow band. The major difference between them is that narrow band UVB light bulbs release a smaller range of ultraviolet light. It has been demonstrated that narrow-band UVB is faster and more effective in clearing psoriasis, leading to longer remissions. In addition, it is effective with fewer treatment sessions per week than broad-band UVB.
During UVB phototherapy, psoriasis may worsen temporarily before improving. The skin may redden and itch. To avoid further irritation, the administered dose of UVB may need to be reduced temporarily.
UVB phototherapy can be combined with other topical or systemic agents to enhance efficacy, although sometimes photosensitivity and burning sensation may be increased. Combining phototherapy with systemic therapies may increase efficacy dramatically and allow the use of lower doses of the systemic medication.
Although both UVB and UVA are found in sunlight, UVB works best for psoriasis, and works exactly the same as UVB in phototherapy centres.
Short, multiple exposures to sunlight are recommended, such as staying under the sun for 5 to 10 minutes in the noon on a daily basis. Gradually exposure time is increased up to 30 minutes, as long as the skin tolerates it. For the treatment to be successful, all affected areas should receive equal and adequate exposure. Do not forget to wear sunscreen on areas of skin unaffected by psoriasis.Avoid overexposure and sunburn. It can take several weeks to see significant improvement. Some topical medications can increase the risk of sunburn, including tazarotene and calcineurin antagonist creams.
Patients under treatment with PUVA or other forms of phototherapy should avoid exposure to sunlight unless directed by a doctor.
Psoralen + UVA (ultraviolet light Α, 320-400 nm)
Like UVB, UVA is present in sunlight. Unlike UVB, it is not equally effective is psoriasis, unless used with a light-sensitising agent, such as psoralen, a substance that is administered topically or orally.
This treatment method is called PUVA, it slows down excessive skin cell growth and can clear psoriasis symptoms for varying periods of time. Stable plaque psoriasis, guttate psoriasis, and psoriasis of the palms and soles are most responsive to PUVA treatment.
The most common side effects of PUVA are nausea, itching and redness of the skin. Drinking milk, taking ginger supplements may limit the symptoms. Antihistamines and topical products relieve itching. The use of sun glasses to protect the eyes is mandatory on the treatment day.