Which guideline is critical when using a laser during surgical procedures?

Using non-reflective instruments during laser procedures is crucial because reflective surfaces can redirect the laser beam unintentionally, potentially causing injury to surgical staff, patients, or causing accidental damage to surrounding tissues. Non-reflective instruments help ensure that the laser energy is directed accurately to the intended target without any risk of the beam being scattered or reflected, which could lead to serious complications.

In the context of this question, it's vital that the instruments used during laser surgeries are designed specifically to minimize the risk of reflection. This includes materials that either absorb or do not reflect laser light. Such precautions are standard practice in laser surgery to maintain a safe and controlled environment.