What is the term for the angle of the nose related to a vertical line when viewed head-on?

The term that defines the angle of the nose in relation to a vertical line when viewed head-on is known as the frontal angle. This angle is crucial in opticianry and other fields related to facial anatomy, as it helps in evaluating the alignment and aesthetics of the face. The frontal angle gives insights into the overall symmetry and proportions of the nose compared to other facial features, which is important for fitting glasses and ensuring a proper aesthetic appearance. Understanding the frontal angle aids in crafting eyewear that harmonizes well with an individual's facial characteristics, contributing to comfort, functionality, and style.

The other terms presented do not pertain to this specific angular measurement. The bifocal angle relates to the design of bifocal lenses, the nasal angle typically refers to the angle between the nasal bridge and nostrils, and the temporal angle is associated with the side of the head or the temple area, making them unrelated to the frontal view of the nose.