Retinal thermal damage threshold dependence on exposure duration for the transitional near-infrared laser radiation at 1319 nm

The retinal damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. In this paper, the in-vivo retinal damage ED(50) thresholds were determined in chinchilla grey rabbits for 1319 nm laser radiation for exposure durations from 0.1 s to 10 s. The incident corneal irradiance diameter was fixed at 5 mm. The ED(50) thresholds given in terms of the total intraocular energy (TIE) for exposure durations of 0.1, 1 and 10 s were 1.36, 6.33 and 28.6 J respectively. The ED(50) thresholds were correlated by a power law equation, ED(50) = 6.31t(0.66) [J] where t is time [s], with correlation coefficient R = 0.9999. There exists a sufficient safety margin (factor of 28~60) between the human ED(50) thresholds derived from the rabbit and the maximum permissible exposure (MPE) values in the current laser safety standards.