A practitioner is required to conduct an investigation of a person's occupation in determining if shatter-resistant lenses are required when?

The correct answer is that a practitioner is required to conduct an investigation of a person's occupation when informed by the person. This aligns with the responsibility of optometrists to take into account the specific needs of their patients, especially those whose occupations may expose them to higher risks of eye injury.

When a patient discloses their occupation, the optometrist should assess whether the nature of that job warrants the use of shatter-resistant lenses. Certain professions, such as those involving construction, manufacturing, or any field that poses a risk of flying debris, may necessitate additional protective eyewear. The input from the patient regarding their work environment is crucial for making an informed decision about lens requirements.

In contrast, the other options represent situations that do not inherently trigger the same obligation. For instance, prior violations or general suspicion without specific information from the patient do not provide the same basis for investigation as direct communication from the individual regarding their occupational risks. This underscores the importance of clear communication and the proactive role that the optometrist takes in safeguarding the visual health of their patients.