What is the major thermal effect of laser exposure in tissues?

The major thermal effect of laser exposure in tissues is biological damage. When laser light interacts with biological tissues, it can lead to a variety of thermal outcomes, primarily due to the absorption of laser energy. This energy generates heat, which can cause changes at the cellular and tissue levels.

Excessive heat can lead to denaturation of proteins, cell death, and disruption of cellular structures. This biological damage can manifest in various ways, depending on the intensity and duration of the exposure, such as burn injuries or changes in cellular functions.

While local vascular flow can be affected by the heat generated during laser exposure, and scattering coefficients and irradiance are important parameters in understanding laser-tissue interaction, they are not the primary thermal outcome. Ultimately, the significant concern in a clinical or experimental context revolves around the biological damage that can occur from thermal effects, making it the correct answer.