The light produced by the sun can be split into the colours we see in a rainbow – at one end of the spectrum are the ultraviolet rays – further divided into ultraviolet rays – further divided into ultraviolet A, B, and C.

UVC is very harmful to all living things but as long as the Ozone layer remains intact, this will not reach earth.

UVB is a short wavelength of light that only penetrates the superficial layer of the skin. We are all at risk of sunburn, but those of us with very fair (Type 1) skin are most at risk.

UVA is a long wavelength of light. It is less abundant than UVB but penetrates the skin deeper and takes longer to burn. UVA can also penetrate window glass.

The use of UV light in the UK is governed by guidelines from the British Photodermatology Group, which look at who should be treated and decide on safe doses. UV light therapy can be effective in three patient types:

• People with severe psoriasis that is not responding to topical treatments.
• People whose psoriasis returns within three to six months of successful treatment as in-patients or day patients.
• People who do not want topical treatment.

UVB – what is it?

People with psoriasis can sometimes be referred to a specialist hospital unit for Ultra Violet Light therapy. UVB light is used to help trigger chemical reactions that affect the function of the cells by reducing their ability to reproduce so quickly.

UVB is used to treat guttate psoriasis or plaque psoriasis, which fails to respond to simple topical treatments.

UVB is present in natural sunlight and can be an effective treatment for psoriasis. The UVB rays work by penetrating the skin, slowing down the rapid growth of skin cells associated with psoriasis. UVB treatment involves exposing the skin to an artificial UVB light source for a set period of time at regular intervals (2 or 3 times a week), usually in a hospital setting under the direct guidance of a phototherapist in accordance with a dermatologist’s recommendations.

There are two types of UVB treatments, broadband and narrowband. Narrowband UVB (TL01) is the commonest type of UVB treatment in the UK. Narrowband UVB works in much the same way as broadband UVB.

The major difference is that narrowband UVB utilises specific wavelengths of UVB that are known to minimise the risk of burning and are effective in the treatment of psoriasis. UVB treatments are safe to use in both adults and children and in pregnancy. UVB can be used as a single treatment or in combination with other topical or systemic medications as recommended by your doctor or healthcare professional.

What happens if I have to have UVB treatment?

If you have several patches to treat over your body you will be expected to stand in a purpose built treatment light box (like an upright sunbed) that is fitted with UVB lamps. However if you have localised areas such as palms and soles smaller units may be used. Usually a treatment is given three times a week, between 20 and 30 treatments are required, although this may vary. The length of time patients are exposed to the UVB will gradually increase over the course of treatment.

Treatment can sometimes cause itching, redness and/or skin tenderness. If this should arise always inform your doctor or healthcare professional administering the treatment. Good patient compliance and patience is called for to obtain successful outcomes with this treatment as it is time consuming and may be restrictive due to employment schedules or other commitments.

The Goeckerman regime

People may be referred to hospital for day treatment with UVB in combination with application of coal tar medications. This regime is called the Goeckerman method. Coal tar preparations are applied to the skin for a length of time then removed before a person is exposed to UVB light. This method can also be combined with steroid medications and scale removers in the early stages of the treatment.

What are the side effects of UVB treatment?

UVB treatment can occasionally cause an initial deterioration in psoriasis before improvement is seen. The skin can become itchy and red due to treatment. If this should happen the next treatment of UVB can be omitted or the dose reduced to prevent any further irritation or discomfort If during the course of treatment coal tar preparations are used these can in some cases cause the skin pores to clog causing small pimple-like eruptions known as folliculitis. These eruptions are caused by not applying the coal tar correctly - it should be applied in the same direction as the hair grows. Folliculitis is not permanent but it may mean the coal tar preparations have to be stopped.

Another side effect of over exposure to UVB is sunburn. This can also occur if you have been using other medications or herbal supplements which can cause sensitivity to light. It is important before you start any courses of any treatment to inform your healthcare professional or doctor of any products that you are taking.

PUVA – what is it?

PUVA stands for psoralen and ultraviolet light A. PUVA is another form of UV light treatment using Ultra Violet A light and a plant extract called a psoralen. This chemical makes the skin more sensitive to light and increases the effect of the UVA light. Psoralen is derived from plants and is normally taken as a tablet or by bathing in a psoralen solution. Like UVB treatment this is usually administered in hospital.

Psoralens and sunlight were used by the Egyptians and Indians for hundreds of years in the treatment of vitiligo (a condition in which areas of the skin lose their colour and become white). More recently psoralens and ultraviolet light A (UVA) have been used for treating psoriasis and other skin conditions. PUVA is often used after other treatments have failed. Total body PUVA is used when at least 20 per cent of the body is affected.

Psoralens

Psoralens are chemicals which are found in more than 30 plants, including lime, lemon, celery, parsley, fig and clove. In PUVA therapy a psoralen drug is taken by mouth, bathed in a solution or applied to the skin as a paint, and the skin is then exposed to UVA. The psoralen acts by making the skin more sensitive to long-wave UV.

The oral methoxypsoralen capsules contain psoralen. These capsules should be taken TWO HOURS before treatment to get the best results. Check this with the doctor or pharmacist. With some preparations this time interval is different. If your capsules make you feel sick, they should be taken with a light meal or a glass of milk. It is important to take them with a similar amount of food on each occasion, as absorption of psoralen can vary.

For topical PUVA, the psoralen paint should be applied sparingly to the affected areas ONE HOUR before treatment. The paint should be applied by using a cotton bud and then allowed to dry. When applying the paint be very careful that it does not run onto clear areas of your skin. You are advised to wash or shower after local PUVA.

Tell the nurse or hospital doctor when you need some more capsules or paint as these are only available from the hospital pharmacy.

UVA

Ultraviolet light A occurs naturally in the sun's rays. In most parts of the world only small amounts reach the earth's surface. PUVA therapy needs large amounts of UVA, so this is provided by special machines.

How PUVA works

In the presence of UVA, the psoralen combines with the cells in the skin to slow down their rate of division. The treatment causes a reddening of the skin and increased production of the natural pigment melanin. This may give you a tan.

The PUVA machine

The machines used contain many fluorescent tubes with a special coating. These tubes give out the UVA needed for PUVA. The tubes are built into boxes, rather like shower cabinets, into which you step for treatment. Some patients dislike the rather claustrophobic feeling of being inside the cabinet, but most patients get used to it. Some elderly patients may find it difficult and uncomfortable to stand up for the required time. Fans are built into the cabinet for ventilation and temperature control. Smaller PUVA units are used for treating small areas of the skin, such as the hands or feet.

During treatment you must wear goggles to protect your eyes. Try not to stare directly at the rays of light during treatment.

The treatment sessions

Treatment time depends mainly on your skin type and how it reacts to sunlight, fair-skinned people, who burn easily, will have a shorter treatment time than dark-skinned people who rarely burn in the sun.

The treatment sessions may gradually be increased from a few minutes up to 20 minutes if your skin tolerates the treatment and does not burn.

If you notice any burning or soreness tell the nurse before further treatment, as the treatment time may need to be reduced or the affected area may need covering. Many men find their face becomes red after treatment, so next time it is often protected by a visor.

Frequency

Treatment is usually given twice a week.. It is not safe to give it more often as any redness or burning can take up to 96 hours to appear hours to appear and burnt skin should be protected from further exposure.

Psoriasis usually clears after 6-8 weeks of treatment. Some people will find they can stop treatment and have long periods free from disease. Continuous PUVA therapy is avoided to reduce the cumulative effects of UVA.

For PUVA therapy you attend as an outpatient and therefore the treatment may not interfere with your work or schooling. If you do experience difficulty with getting time off, your doctor may be happy to write to the place concerned.

Precautions to take

• Always be ON TIME for your appointment as the clinics run to a very tight schedule.

• Methoxypsoralen capsules sensitise your skin and eyes to sunlight for about 8 hours. To prevent the possibility of cataract formation you must wear sunglasses, which protect your eyes against UVA, for 24 hours after taking the capsules. The phototherapy department can test your sunglasses for you. During this time you must also wear suitable clothing to protect your skin. The sun acts like the PUVA machine and can cause burning if your skin is exposed for long periods after using psoralens.

• Skin that has been painted for topical PUVA should be protected from direct sunlight for 12 hours after application of the paint. Remember that UVA radiation from the sun can penetrate glass and light fabrics, so remain in the shade if possible.

• During the summer, if you must go out for long periods, wear protective clothing and a good sun block which has been recommended by your doctor, many sunscreens do not protect adequately against UVA.

• Dry, itchy skin can be treated by creams such as aqueous cream or emollients; these are available on prescription and also over the counter. You are advised not to use bubble baths as these can dry out your skin.

• Instead, add prescribed bath oils or emollient to the bath water. After adding this to the water, soak in the bath for 10-15 minutes.

• Please inform the nurse if you have been started on any new medication as some medicines make you more sensitive to the fight.

• Women of child bearing age should not become pregnant while using psoralens, but previous use of PUVA does not affect subsequent pregnancies.

• You should not use a sun bed while on PUVA therapy.

• Prior to treatment, your skin should be clean and dry. PUVA therapy may be less effective if your skin is covered by certain creams and ointments.

• Do not wear deodorants, perfume or aftershave during treatment. Some of them contain oils which sensitise the skin to light and may result in patchy discolouration of the skin which takes many months to fade.

• You should make an appointment to see your doctor at intervals.

• People who are unreliable in attending the clinic, in using their psoralens or wearing their protective sunglasses and clothes will not be treated with PUVA.

Side effects of PUVA

Side effects may occur from PUVA, but these are reduced if you follow the precautions.

1. Your skin may burn, blister or become dry and itchy.

2. Long term use of PUVA may age the skin.

3. Prolonged exposure to sunlight and hence to PUVA can cause skin growths to appear. If you notice any such changes, please let the doctor or nurse know.

4. There is a theoretical risk of cataract formation in the eye, but this has not happened where eye protection has been used.

The most common short-term side effects of PUVA are nausea, itching and redness of the skin. Drinking milk or ginger ale, taking ginger supplements or eating while taking oral psoralen may prevent you from feeling sick. Antihistamines, baths with oatmeal products or applying topical creams/ointments/gels containing capsaicin may help relieve the itching caused by PUVA.

Advantages of PUVA

1. It does not involve the use of messy or smelly creams and ointments.

2. There are no stains to ruin clothes or bed linen.

3. You may acquire a pleasant tan.

4. You attend as an outpatient.

PUVA is a powerful and pleasant way of treating certain skin conditions. At present it is reserved for patients with' relatively severe psoriasis or other skin conditions. PUVA is not a cure for your skin disorder but it will help to control it.

Where are phototherapy treatments available?

It should be mentioned that not all phototherapy treatments will be available in every hospital but your doctor will be able to advise you of availability to such specialised centres.

Maximum lifetime exposure to phototherapy

It is recommended by the British Photodermatology Group that individuals should not be exposed to more than 1,000 joules or 250 treatments of PUVA or 300 treatments of narrowband UVB in their lifetime.

Skin cancer

There is no direct and conclusive evidence to suggest an increased risk of skin cancer from UVB treatments for psoriasis. It is important that you get your skin examined by a doctor at regular intervals to check for any small abnormalities which in most cases if detected early can easily be removed without any serious consequences.

Some healthcare professionals may suggest using a sunscreen before treatment on any areas of skin that are not affected because this minimises over exposure to UVB. The face is usually protected with a visor once any facial psoriasis has cleared.

Useful information:
British Photodermatology Group
www . bad.org.uk / guidelines

© PAPAA 2008

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