Which of the following factors is NOT essential during a client consultation for eyelash extensions?

During a client consultation for eyelash extensions, it is crucial to assess several factors that impact both the safety and comfort of the client. Each of the first three factors listed plays a significant role in ensuring that the extensions can be applied without any adverse effects.

Healthy eyes are essential because any existing issues such as infections or conditions can exacerbate with the application of extensions. Similarly, verifying that the client does not have an allergy to the adhesive is imperative for preventing allergic reactions that could lead to discomfort or complications. Also, ensuring that the client feels comfortable with the procedure is key to fostering trust and allowing them to express any concerns or preferences.

While age may provide some insights into a client's overall health and lifestyle, it is not a strict requirement for the application of eyelash extensions. For adults, age itself typically does not affect the procedure or the results directly. Therefore, while it could be considered as part of understanding the client's background, it is not an essential factor in the same way that the health of the eyes, potential allergies, and comfort with the procedure are.