What are three ways the skin can be damaged by lasers?

• A. Photomechanical; Thermal; Photochemical
• B. Photothermal
• C. Thermochemical
• D. Photoacoustic

Answer: (A)

Lasers can damage skin through three primary interaction modes: photomechanical, thermal, and photochemical. Photothermal damage comes from laser energy being converted to heat, raising tissue temperature and causing coagulation or thermal necrosis. Photochemical damage happens when photons drive chemical reactions in cells, producing reactive species that injure tissues even without a large temperature rise. Photomechanical damage results from rapid energy deposition creating mechanical stresses, shock waves, or cavitation that disrupt tissue structure. The other options don’t capture all three pathways: one describes only heat, another uses a term (thermochemical) that isn’t a standard separate damage mode, and the last refers to photoacoustic effects, which are a consequence of rapid heating but not a standalone primary damage mechanism.