Ocular temperature elevation induced by threshold in vivo exposure to 1090-nm infrared radiation and associated heat diffusion

Abstract

An in vivo exposure to 197 W/cm 2 1090-nm infrared radiation (IRR) requires a minimum 8 s for cataract induction. The present study aims to determine the ocular temperature evolution and the associated heat flow at the same exposure conditions. Two groups of 12 rats were unilaterally exposed within the dilated pupil with a close to collimated beam between lens and retina. Temperature was recorded with thermocouples. Within 5 min after exposure, the lens light scattering was measured. In one group, the temperature rise in the exposed eye, expressed as a confidence interval (0.95), was 11+/-3 degrees C at the limbus, 16+/-6 degrees C in the vitreous behind lens, and 16+/-7 degrees C on the sclera next to the optic nerve, respectively. In the other group, the temperature rise in the exposed eye was 9+/-1 degrees C at the limbus and 26+/-11 degrees C on the sclera next to the optic nerve, respectively. The difference of forward light scattering between exposed and contralateral not exposed eye was 0.01+/-0.09 tEDC. An exposure to 197 W/cm 2 1090-nm IRR for 8 s induces a temperature increase of 10 degrees C at the limbus and 26 degrees C close to the retina. IRR cataract is probably of thermal origin.