Lasers (acronym for light amplification by the stimu-lated emission of radiation) are high-intensity coherent light sources of a specific wavelength. The photons are absorbed by a target chromophore (e.g. a tattoo pigment, melanin in hair, oxyhaemoglobin in blood vessels) and, depending on the energy, duration of the pulse of emission and the thermal relaxation time, cause local, sometimes microscopic, tissue destruc-tion. Lasers are now being used to treat many skinlesions including capillary haemangiomas, tattoos, epidermal naevi, pigmented lesions, seborrhoeic ker-atoses, warts and tumours.
Since 1960, when T.H. Maiman won the Nobel Prize for inventing the first laser, technology has advanced rapidly and many types of laser are now available for clinical use. Most treatments can be carried out under local anaesthetic and as an out-patient. Port-wine stains can be treated successfully in children as well as in adults, using the flashlamp pulsed dye laser emitting light at 585 nm. Most tat-toos can be removed by treatment with a Q-switched ruby laser (694 nm), a flashlamp pumped pulsed dye laser (510 nm) or an alexandrite laser (760 nm). Scarring should not be a problem. Benign but un-sightly pigmented lesions such as café au lait marks, melasma, the naevus of Ota and senile lentigines can be greatly improved by treatment with the flash-lamp pumped pulsed dye laser (510 nm) and the Q-switched neodymium: yttrium aluminium garnet (Nd:YAG) laser (532 nm). Unwanted hair can be per-mamently removed with a pulsed diode laser (800 nm) or with a Q-switched Nd:YAG laser emitting light at 1064 nm.
Rhinophyma, sebaceous gland hyperplasia, sebor-rhoeic keratoses, syringomas and many of the signs of chronic photodamage (e.g. rhytides, actinic cheilitis, actinic keratoses) can be helped by cutaneous resur-facing using CO2 lasers emitting a wavelength of 10 600 nm (infrared) or a Q-switched erbium (Er): YAG laser emitting pulsed waves of 2940 nm in the near infrared, which is absorbed by water 10 times more efficiently than the pulsed CO2 laser beam (Fig. 24.14). Good postoperative care is important, as the patient is left with what is essentially a partial thickness burn which heals by re-epithelialization from the cutan-eous appendages. After profuse exudation for 24–48 h the treated area heals, usually in 5–10 days. Absolute contraindications for laser resurfacing include the use of isotretinoin within the previous year, con-current bacterial or viral infection and any hint of ectropion. Dark skin (skin types V and V1;) should be treated with special care as pigmentary side-effects are common. Cutaneous laser resurfacing is more effective on the face than on the neck and extremities.
Laser treatments should be carried out only by fully trained specialists