24.1 INTRODUCTION

The ability of the surgeon to focus a laser beam to a small spot and precisely coagulate or vaporize tissue led to the immediate acceptance of lasers as a photothermal device for medical applications. Retinal photocoagulation with an argon laser ( ? = 488 nm, 514.5 nm) became the method of choice for treatment ofdetached retina. Also, because oftheexcellent absorption of the argon wavelength by blood, the laser was initially selected for coagulation of enlarged blood vessels in the treatment of port wine stain. For procedures that required coagulation of tissue to depths of a centimeter or more, the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1.06 m) was selected because of the deep penetration of near-infrared wavelengths in tissue. In contrast, the CO ₂ laser(10.6 m)becamethestandard for ablation of tissue because of its shallow penetration depth of approximately 20 m.

The rapid development of continuous-wave (cw) and pulsed lasers has produced a cornucopia of wavelengths, powers, and exposure durations available for medical applications. Laser-tissueinteractionsnowincludephotochemical,photomechanical,andphotodissociation in addition to classical photothermal interactions. The public demand for the use of lasers in medicine has been so great that Consumer Reports tried to evaluate the effectiveness of medical applications in an article "Laser Surgery: Too Much, Too Soon?"1

The article reports that lasers are the preferred treatment for: