[Sensory responses to Nd:YAG laser irradiation in humans]

Pain and detection thresholds upon Nd:YAG laser irradiation were studied in healthy human subjects. The output power was set at 100 mW (1.36 W/cm2), 300 mW (4.11 W/cm2), 600 mW (8.22 W/cm2), 800 mW (11.0 W/cm2) and 1,000 mW (13.7 W/cm2). The duration was 5 seconds. The irradiation was done to the hand dorsum using the non-contact method (distance between the subject and the laser tip was 5.0 mm). After irradiation, the detection threshold was about 600 mW and the pain threshold was about 1,000 mW. The skin temperature was 34.9 +/- 0.64 degrees C before irradiation and 38.0 +/- 0.45 degrees C after a 5-sec-irradiation at 1,000 mW. No skin damage was observed after the irradiations.