Excimer 308-nm light is a form of targeted phototherapy that delivers a specific wavelength (308 nm) of ultraviolet B (UVB) radiation using an excimer laser or an excimer lamp. Both have shown similar results regarding efficacy, but have technical differences.

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The UV ray generated by the excimer light is delivered via a hand-held wand that focuses on the lesion. Compared with narrowband UVB, its advantages are:

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• Healthy skin surrounding the affected areas is not exposed to radiation

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• Different templates are used according to the area to be treated

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• A higher dose of radiation can be delivered, with a reduced cumulative dose of irradiation

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• In some cases, a shorter course of treatment is effective

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• It can be used in areas difficult to reach with conventional phototherapy, such as ears and genitals

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• It can be used in children, as it is a relatively friendly–looking piece of equipment.

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Excimer laser therapy is an option for the treatment of localised vitiligo and moderately severe localised psoriasis and unresponsive to topical treatments.