RESUMO
With the advent of such systems as the airborne laser and advanced tactical laser, high-energy lasers that use 1315-nm wavelengths in the near-infrared band will soon present a new laser safety challenge to armed forces and civilian populations. Experiments in nonhuman primates using this wavelength have demonstrated a range of ocular injuries, including corneal, lenticular, and retinal lesions as a function of pulse duration. American National Standards Institute (ANSI) laser safety standards have traditionally been based on experimental data, and there is scant data for this wavelength. We are reporting minimum visible lesion (MVL) threshold measurements using a porcine skin model for two different pulse durations and spot sizes for this wavelength. We also compare our measurements to results from our model based on the heat transfer equation and rate process equation, together with actual temperature measurements on the skin surface using a high-speed infrared camera. Our MVL-ED50 thresholds for long pulses (350 micros) at 24-h postexposure are measured to be 99 and 83 J cm(-2) for spot sizes of 0.7 and 1.3 mm diam, respectively. Q-switched laser pulses of 50 ns have a lower threshold of 11 J cm(-2) for a 5-mm-diam top-hat laser pulse.
Assuntos
Queimaduras/fisiopatologia , Raios Infravermelhos/efeitos adversos , Lasers/efeitos adversos , Modelos Biológicos , Lesões por Radiação/fisiopatologia , Temperatura Cutânea/efeitos da radiação , Pele/lesões , Animais , Queimaduras/etiologia , Queimaduras/patologia , Simulação por Computador , Limiar Diferencial/efeitos da radiação , Relação Dose-Resposta à Radiação , Técnicas In Vitro , Doses de Radiação , Lesões por Radiação/etiologia , Lesões por Radiação/patologia , Medição de Risco/métodos , Fatores de Risco , Pele/patologia , Pele/efeitos da radiação , SuínosAssuntos
Lasers/efeitos adversos , Retina/lesões , Animais , Macaca mulatta , Modelos Biológicos , Temperatura , Condutividade TérmicaRESUMO
The relationship between pre-exposure fundus temperature and the temperature rise which produces a threshold burn was examined in rabbit eyes exposed to an Argon c. w. laser (4,880 A) for 10 seconds. The posterior pole of the eye was surgically exposed and a 20-micron tip diameter probe was inserted into the ocular fundus to measure temperature rises. The temperature rise for threshold burns linearly increased as preexposure fundus temperature decreased, implying a constant threshold temperature. Threshold temperature was indirectly predicted to be 52.4 degrees C. using a system with an estimated error of plus or minus 1/2 degrees C.