Targetted phototherapy includes technologies such as the excimer laser, and UV light sources delivered via fibre optic cables, such as Dualight.

At Anwyl we use Dualight, which provides targeted broadband UVB (290-330nm with peak emission in the narrowband wavelengths) or broadband UVA (330-380nm with peak emission about 365nm ie in UVA1 range). There is a fibreoptic cable for light delivery with a 3.62 cm² exit aperture. For UVA one can select doses up to 5 J/cm², and for UVB up to 3120 mJ/cm².

There are several advantages to targeted phototherapy:

• uninvolved areas are spared, minimising side effects such as burns, and long term risks such as skin cancer
• higher doses can be used especially with UVB treatment of psoriasis, where 5 or 6 times the minimal erythema dose can be used, rather than starting with 50-70% of the minimal erythema dose - this results in a much faster treatment response
• the manoeuverable handpiece allows for difficult areas such as the ears, or armpits, to be treated.

The disadvantage is that widespread skin disease cannot be treated in this fashion - one or two large plaques (roughly equal to an A4 page in their total combined size) or multiple small plaques (roughly equal to an A5 page in their total combined size) are about the maximal area that could be treated.

Treatment is usually carried out twice a week, following phototesting to determine the starting dose.