Which form of laser-tissue damage is primarily associated with chemical changes in cells rather than mechanical tearing or heating?

• A. Thermal
• B. Photomechanical
• C. Photochemical
• D. Radiation-induced

Answer: (C)

Photochemical damage happens when light triggers chemical reactions inside cells, often through excited chromophores that generate reactive oxygen species and oxidize biomolecules. This leads to chemical changes in cellular components without relying primarily on heat or mechanical disruption. The question emphasizes chemical changes, which is the hallmark of photochemical damage. In contrast, thermal damage arises from tissue heating and coagulation, and photomechanical damage comes from rapid energy deposition causing mechanical disruption like cavitation. Radiation-induced damage would involve ionizing radiation effects, not typical for the described laser-tissue interaction. So the form described is photochemical damage.