Complications of laser surgery.

Medical lasers have advanced so rapidly over the past 10 years that a thorough review of the complications of laser surgery must be based on fundamental laser physics in order to provide a general working framework of knowledge. New laser systems are being introduced and older systems have been improved, often making modern laser technology appear intimidating. In order to understand and even predict the side-effect profile of a specific laser, one must comprehend the principles on which the laser operates. The first medical lasers to be designed, continuous wave lasers, are effective but are extremely operator-dependent and can potentially result in a great deal of scarring. In 1983, the theory of selective photothermolysis was introduced that enabled physician-scientists to design lasers that were highly selective and safer to operate. Lasers designed on the theory of selective photothermolysis are capable of affecting a specific target tissue without a high risk of scarring and pigmentary changes. They accomplish this task by producing a wavelength and pulse duration that are best absorbed by a specific target. Not all modern lasers use selective photothermolysis and therefore may operate in either a continuous wave, quasi-continuous wave, pulsed, or Q quality-switched mode. Continuous wave lasers are least selective and tend to produce unwanted tissue damage and scarring through heat dissipation. Quasi-continuous wave lasers attempt to limit unwanted thermal damage by producing a series of brief laser pulses or by chopping a continuous wave beam; however, they still have a relatively high risk of causing nonspecific tissue damage and thermal injury. The pulsed and Q-switched systems adhere most closely to the laws of selective photothermolysis and result in the most selective destruction with the lowest risk of scarring and unwanted thermal diffusion. Of course, any laser system can potentially result in scarring and tissue damage; therefore, adequate operator education and skill are essential when using any medical laser.