Search

The inner cars of pigeons have been irradiated by means of a Q-switched ruby laser with an output pulse energy of about 0.3 joule. Atrophy of the epithelium and changes in the bony and membranous labyrinth have been observed. The ability of the laser beam to penetrate thin slices of bone has been tested. The biological effect of the laser beam seems to be mainly thermal, but ultrasonic waves created in the focal spot may contribute.

Minute and reproducible inner-ear lesions were produced in surviving guinea pigs by using an argon laser. Preselected areas, mainly in the cochlea, were irradiated for 0.5-30 seconds at power densities at the focal spot of around 1 to 2 kW/cm2. the laser beam did not perforate the otic capsule but produced superficial changes. Beneath the impact point in the bone, a rounded lesion was observed in the vascular stria. Damage to the organ of Corti of varying extent occurred, depending on the energy dosage delivered. the organ of Corti in the impact area was characterized by either a complete loss or a reduced number of lipid granules in the Hensen cells. Hair-cell changes covering about one-third of a coil were frequently noted. Variations in the appearance of the cilia after irradiation are presented. Expansions of the tips of the cilia on the outer hair cells are described. the outer hair cells proved to be more affected by the laser irradiation than the inner hair cells. Scanning electron microscopy and p...