Which feature is critical in selecting a laser for therapeutic use?

The wavelength of the light emitted by a laser is a critical feature in selecting a laser for therapeutic use because it determines how the laser interacts with biological tissues. Different wavelengths penetrate tissues to varying depths and are absorbed by different chromophores (light-absorbing molecules) in the body, such as hemoglobin and melanin. This absorption affects the laser's effectiveness in treating specific conditions, as certain wavelengths may target vascular structures while others might have a more significant impact on pigmented lesions or deeper tissues.

Choosing the appropriate wavelength is essential for ensuring safe and effective treatment, maximizing therapeutic outcomes while minimizing damage to surrounding healthy tissues. Other factors, such as the size of the equipment, color, and price, while possibly relevant in a broader context, do not directly influence the physiological interaction that occurs during laser therapy as profoundly as wavelength does.