Which form of laser-tissue damage is associated with rapid mechanical disruption rather than heating or chemical changes?

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

Answer: (C)

When laser energy is delivered in an extremely short pulse, the tissue can’t dissipate the energy as heat fast enough. The rapid energy deposition creates a sudden pressure rise, leading to plasma formation and cavitation bubbles that mechanically disrupt cells and structures. This rapid, physically driven damage is called photomechanical damage. It stands in contrast to thermal damage, which comes from heating and coagulation, and photochemical damage, which involves light-triggered chemical reactions. Photomechanical effects are often linked to ultra-short laser pulses (nanoseconds or shorter) and are responsible for rapid, non-thermal tissue disruption.