ABSTRACT
The objective of laser photocoagulation is the conversion of light energy into thermal energy with a subsequent temperature rise leading to thermal denaturation or “coagulation”. For argon laser coagulation, a range of 1-20 W is most frequently encountered with 1-3 W being used for ophthalmology and 5-10 W for gastrointestinal bleeding. In general, scattering is an advantage for coagulation, since it diffuses light and reduces the probability for deep damage or damage to organs adjacent to the serosa if endoscopic coagulation is performed. If it becomes sufficiently hot, denaturation of protein ensues or in other words, thermal coagulation. Thermal coagulation begins in a range from 50°C-80°C. If thermal energy is further deposited beyond that which is necessary to cause therapeutic coagulation, the temperature will continue to rise to 100°C and remain there until the water in situ is evaporated. Laser coagulation of 100 W implies 10,000 times the power of this threshold level.
