In lasers, photothermolysis is defined as turning light into heat to destroy target tissue.

• A. Turning light into heat to destroy target tissue
• B. Reflection without heat
• C. Cooling tissue
• D. Diffusion

Answer: (A)

Photothermolysis is about using light that gets absorbed by a specific tissue target and is converted into heat to damage or destroy that target while minimizing injury to surrounding tissue. This conversion of light energy to heat is what enables the selective destruction of pigmented or vascular structures with precision, a foundational concept in laser therapy. The other ideas don’t fit: reflecting light without heat won’t injure tissue, cooling tissue reduces heat rather than producing it, and diffusion describes how particles spread rather than how laser energy creates tissue damage.