Ruby laser-assisted hair removal: an ultrastructural evaluation of cutaneous damage

Ruby laser-assisted hair removal is thought to act via selective phototherm olysis of melanin in the hair follicles. Although initial clinical trials o f permanent hair removal using ruby lasers are promising, the exact mechani sms of hair destruction and the potential damage to other structures of ski n are not known. The aim of this study was to evaluate the cutaneous ultras tructural changes following ruby laser hair removal. Nineteen healthy Caucasian patients with dark (brown/black) hair were treat ed with the ruby laser and biopsies taken after 0, 2, 3,5, 7, 14 and 21 day s. Specimens were examined by light and electron microscopy. Laser-treated specimens showed widespread coagulation and charring of subcu taneous hair shafts. These obviously damaged follicles were randomly disper sed amongst intact follicles within the same treatment sites. Microscopic c hanges were also seen in the basal epidermis where melanin was concentrated , irrespective of any obvious macroscopic damage. A low level of inflammato ry response seen up to 2 weeks after treatment always followed laser treatm ent. Suprabasal epidermal necrosis was only seen in patients with blister f ormation after treatment. Ruby laser irradiation results in selective damage to the hair follicles, w ith microscopic changes to the basal epidermis. The damage is probably comp ounded by the inflammatory response to the damaged hair. The normal appeara nce and distribution of collagen in the dermal layer supported the clinical evidence that laser-assisted hair removal, if performed correctly, does no t lead to scar formation. (C) 1999 The British Association of Plastic Surge ons.