Laser Skin Resurfacing

Abstract

The zone of thermal damage can be reduced by applying the principle of selective photo thermolysis,⁸ which states that selective heating can be achieved by preferential laser light absorption and heat production in the target chromophore with heat being localized to the target by a pulse duration shorter than or equal to the thermal relaxation time (time for the target to cool by 63%) of the chromophore. The thermal relaxation time for the 20 to 30 μm thickness of water-containing tissue that absorbs the CO₂ laser light is less than 1 millisecond.⁹ To limit collateral thermal damage, the CO₂ laser has to be pulsed or scanned across the tissue with a tissue dwell time less than or equal to the thermal relaxation time (1 millisecond). In addition, sufficient energy has to be delivered in that short time to achievetissue vaporization with a single pulse or