Effect of laser light alone and laser light with methylene blue on wound temperature. Temperature was measured using a thermistor tunnelled into the centre of the wounds. There was an immediate increase in the temperature of the wounds following the start of irradiation with laser light of 665 nm wavelength and power rating of 200 mW/cm2. There was a bigger increase in temperature in the PDT treated wounds (black squares) than in the light only (grey triangles) treated group. The temperature dropped upon cessation of irradiation.