Residual thermal damage resulting from pulsed and scanned resurfacing lasers

BACKGROUND. Laser resurfacing with rapidly scanned or pulsed carbon dioxide (CO₂) lasers has evolved rapidly in recent years. These lasers vaporize small amounts of tissue, while leaving minimal residual thermal damage. OBJECTIVE. To compare the depth of residual thermal damage of two of the most commonly used CO₂ laser systems. A rapidly scanned laser was compared to a short-pulse laser system. METHODS. Laser treatment was performed on abdominoplasty specimens prior to removal in four subjects. One, two, or three passes of the two most commonly used energies were administered using each laser system. RESULTS. The depth of thermal damage increased with a greater number of passes with each laser system. Higher energies resulted in greater residual thermal damage with each system after the first pass up to three passes, which was the maximum number of passes administered. Combining the second and third passes, residual thermal damage was remarkably similar when comparing the pulsed and scanned lasers. CONCLUSIONS. The most commonly used energy settings of two lasers with very different modes of action resulted in remarkably similar depths of thermal damage, suggesting that the zone of thermal damage may correlate with clinical outcome. In addition, the zone of thermal damage enlarges as the number of passes increases from one to three.