PILOT ULTRASTRUCTURAL EVALUATION OF HUMAN PREAURICULAR SKIN BEFORE AND AFTER HIGH-ENERGY PULSED CARBON-DIOXIDE LASER TREATMENT

Background: Carbon dioxide laser resurfacing has recently come into fa vor for the treatment of photodamaged skin. While the clinical and his tologic effects of high-energy short-pulse carbon dioxide lasers on hu man skin have been investigated, the ultrastructural effects of these lasers have not been documented. Our objective was to study the ultras tructural effects of a high-energy pulsed carbon dioxide laser on phot odamaged human skin. Observations: Before laser surgery, the ultrastru ctural changes characteristic of photodamaged skin were evident. Immed iately after treatment, there was extensive coagulation necrosis of th e epidermis and papillary dermis. Thirty days after treatment, there w as no evidence of intercellular or intracellular edema, and ordered di fferentiation of the epidermal keratinocytes, with a loss of keratinoc yte dysplasia, was seen. Increased numbers of desmosomes and tonofibri ls were noted. New deposition of collagen was present in the papillary dermis. The ultrastructural findings seen at 90 days after treatment were similar to those seen at 30 days, apart from increased organizati on of collagen fibers in the papillary dermis. Conclusions: Treatment with the high-energy pulsed carbon dioxide laser appears to reverse th e epidermal and dermal changes of photoaging on an ultrastructural lev el. These changes appear morphologically to be consistent with previou sly described clinical and histologic changes following laser resurfac ing.