Abstract
The present study focuses on the photophysiological effects on the brain vessel of guinea pigs by Ar laser irradiation in two wavelengths (λ=351, 488nm). We applied the reflectance measurement to know the extent of Evans blue (EB) leakage through the brain vessels damaged by the laser irradiation. Moreover, we observed the brain tissue with a transmission electron microscope (TEM).
EB leakage started when the intensity of 351nm Ar laser irradiation was more than 1W/cm2, while that of 488nm was more than 60W/cm2. Additionally, the power of inducing EB leakage at the 351nm irradiation was approximately ten times as strong as the 488nm. In case of recurrent Ar laser irradiations to a spot of brain surface, EB leakage could be observed only during irradiations.
TEM revealed (1) opening of tight junction between endothelial cells, (2) vacuolar degeneration of glial cells. (3) swelling or disruption of mitochondria, in the irradiated spot.
These studies show that the Blood-Brain Barrier (BBB) may be injured by the Ar laser irradiation. And the photophysiological effects for the BBB in Ultra-Violet (λ=351nm) irradiation is much stronger than in 488nm.
