Evaluation of the effect of long-term pulsed laser irradiation on cochlear function in Mongolian gerbils ( <i>Meriones unguiculatus</i> )

This study evaluated the effects of infrared laser exposure on cochlear function in Mongolian gerbils. A 6.6-W/cm2 laser induced a stable cochlear response for 870 min, whereas higher irradiation levels resulted in a progressive and significant decline in response. The auditory-evoked compound action potential recorded before and after prolonged laser irradiation revealed that laser irradiation at 105.6 W/cm2 caused a prominent reduction in compound action potential across several frequencies, with the largest reduction occurring near the frequency corresponding to the irradiation site. These results demonstrate that laser irradiation at 6.6 W/cm2 or below can elicit a stable cochlear response, and suggest that prolonged laser irradiation potentially causes frequency-specific damage around the stimulated site.