Phototherapy is the use of light in the treatment of skin diseases. It has been noted in ancient times that psoriasis often improves with exposure to the sun. Sunlight consists mainly of visible light, ultraviolet A and ultraviolet B (UVA and UVB) light. Phototherapy reproduces the action of sunlight in a scientific and controlled manner.
Several types of phototherapy are available. Narrow-band UVB (NBUVB), UVA/NBUVB (in combination) and PUVA (psoralen + UVA) are the common types used. Your doctor will advise you on the most appropriate phototherapy for your skin condition.
Phototherapy has been found to be effective in a range of skin conditions. It is used most widely in psoriasis, vitiligo and atopic dermatitis.
Phototherapy suppresses skin inflammation and restores the balance of the skin immune system. As a result, hyperproliferation of skin cells is reduced. There are probably other beneficial actions of phototherapy that are yet to be studied.
A bath is recommended in the morning before phototherapy. This will hydrate the skin. Emollients should be applied before treatment. Treatment is normally given 3 times a week at the beginning. Multiple sessions of treatment may be required before any improvement of the skin condition is seen. Once the skin lesions have cleared, periodic treatment (1x per week to 1x per fortnight) may be continued to maintain clearance.
PUVA is an effective phototherapy modality utilizing both UVA and a photosensitising agent (psoralen) which enhances the effect of UVA light. The psoralen has to be ingested by mouth or applied topically (in the form of paint, soak or bath) before the treatment session. Avoidance of the sun and wearing of sun-protective clothing and sunglasses are necessary for 24 hours after oral psoralen ingestion. PUVA is more effective than UVB phototherapy but it is more cumbersome to use.
This is the most common way to deliver UVB. It is safer and more effective than conventional UVB in treating psoriasis. It has become the preferred method of delivering UVB phototherapy. It does not require the use of psoralen as in PUVA.
This is a new advance in phototherapy treatment, combining the use of both UVA and NBUVB. It has been found to be effective in the treatment of atopic dermatitis. It is a safe modality which does not require the use of psoralen. It probably has fewer side effects including UV burn.
This is a recently introduced phototherapy treatment modality and represents a major advance in treating localised skin diseases. It has been found to be effective in treating eczema and psoriasis affecting hands/palms and feet/soles, and certain skin conditions such as morphoea and lichen sclerosus. The main side effects are darkening of the treated skin area and burning (rare).
This is a new effective method to treat localised skin areas without subjecting the whole body to UV light. Examples are Excimer laser and Multiclear®.The hand piece is held near target skin area and UV light emitted is directed at that particular area to achieve its desired effect. It has been found to be effective in the treatment of localised vitiligo, psoriasis and eczema.
Photodynamic therapy (PDT) is a new form of light treatment found to be effective in treating pre-cancerous lesions such as actinic keratosis and Bowen’s disease, and skin cancers such as the superficial form of basal cell carcinoma (BCC). This treatment involves the application of a photosensitising cream (methyl aminolevulinate) with subsequent illumination of red light from a special light device onto the lesion. The most common side effect is pain although this is often well tolerated. A repeated treatment is performed one week later. One of the major advantages is avoidance of surgery and subsequent scarring.
Phototherapy is a safe treatment modality in general. Dryness of skin and itch are the commonest side effects, which can be alleviated by frequent application of a moisturiser.
Patients may develop a tan after a period of phototherapy similar to sunburn happens only very rarely. In those patients with many years of continuous phototherapy, skin cancers are the major concern especially with PUVA treatment. The risk is minimal in short-term therapy. Skin cancers can be easily removed in early stages. Skin aging is another side effect of long-term therapy.
Both UVA and UVB may be used in combination with other medications like acitretin and methotrexate. Combination treatment increases effectiveness in clearing psoriasis. Re-PUVA is the combination of retinoid (e.g. acitretin) and PUVA. It is generally recommended for those who fail to respond to UVB or PUVA alone.