How do lasers work in medical applications?

In medical applications, lasers work primarily by emitting concentrated light energy that is precisely absorbed by targeted tissues. This principle of selective photothermolysis allows lasers to target specific chromophores—such as melanin in hair or hemoglobin in blood—without affecting the surrounding tissues. The laser light is absorbed by these targeted tissues, converting the light energy into heat, which then leads to the desired therapeutic effect, such as hair removal or the reduction of vascular lesions.

This mechanism explains why using laser light is highly effective in various medical and cosmetic procedures, as it allows for precision and minimizes damage to adjacent areas. The other choices, while they reflect some processes related to skin treatment, do not accurately describe the fundamental operation of lasers in medical applications. For example, lasers do not inherently generate heat across all skin layers nor do they involve chemical reactions in the skin or apply pressure, which differentiates their use from other treatment modalities.