Comparison of 1540-nm laser-induced injuries in ex vivo and in vitro rabbit corneal models

Despite the increasing use of infrared lasers in medical, industrial, and military settings, data on threshold radiant exposures and median effective dose $(ED50)$ as they relate to laser-tissue interaction are limited. Our goals were to determine the $ED50$ for single-pulse, 1540-nm laser exposures in ex vivo and in vitro rabbit corneal models and to characterize the histopathological changes associated with the laser-tissue interaction. An erbium-glass laser was used to deliver single, 1540-nm wavelength pulses to 27 ex vivo and 24 in vitro rabbit corneal models. The ex vivo model was exposed to single pulses of 0.8-ms duration and radiant energies ranging from $17.61J∕cm2$ to $42.26J∕cm2$. The in vitro corneal models were exposed to single pulses of $0.8ms$ duration and had radiant exposures ranging from 14.87 to $29.72J∕cm2$. Tissue exposure sites were observed for presence of a lesion immediately post-exposure and $24h$ after exposure. Histopathological evaluations of tissue exposure sites were conducted $24h$ after exposure. The $ED50$ was determined to be $21.24J∕cm2$ for the in vitro rabbit corneal models and $30.86J∕cm2$ for the ex vivo corneal models. Both the in vitro and ex vivo models displayed similar histopathological responses of tissue necrosis and epithelial cell proliferation.