Laser-assisted hair transplantation: Histologic comparison between CO2 andHo : YAG lasers

BACKGROUND. Various laser wavelengths and devices have been advocated for u se in the creation of recipient channels during hair transplant surgery, in cluding flash-scanned CO2, Ho:YAG (lambda = 2.12 mum), and Er:YAG (lambda = 2.94 mum). OBJECTIVE. TO determine the tissue injury caused by flash-scanned CO2 and p ulsed Ho:YAG lasers during the creation of hair transplant recipient channe ls and to assess the efficacy of the Ho:YAG laser. METHODS. Recipient channels were created in vivo in human scalp tissue usin g both lasers, and were excised and prepared for histologic examination. Op tical micrometry of tissue sections was used to assess thermal injury. RESULTS. The Ho:YAG laser created jagged, irregular-shaped channels with la rger zones of thermal injury (superficial deepithelialization, thermal necr osis, and thermal damage). In contrast, the CO2 laser produced well-defined cylindrically shaped channels free of cellular debris with minimal epithel ial disruption and significantly less lateral thermal injury. CONCLUSION. Given that the Ho:YAG produced larger regions of thermal injury and recipient channels that were unacceptable for graft, the CO2 laser rem ains the better choice for the creation of recipient channels during hair t ransplant surgery. However, ongoing research will be necessary to determine the optimal laser wavelength and/or devices for this procedure.