Ipsilateral alar angle

The outer eye corners form the upper span, and the junction between the nose and upper lip forms the lower point. The angle describes how far that point sits beneath the available eye span. Lowering the nasal base deepens the triangle and reduces the angle; spreading the outer eye corners opens it.

Despite the name, the marked points do not include the nasal wings. Widening the nasal base without moving its central junction or the outer eye corners does not directly alter the angle. Nasal breadth instead changes how much of the space inside the triangle the nose occupies.

A larger angle can come from longer eye openings that extend the outer corners, or from wider spacing that moves the eyes apart. Long eyes around a modest gap fill the upper span differently from short eyes around a wide gap, even when the outer corners end at similar positions.

Bringing the nasal base closer to the eye line also increases the angle. The centre becomes shallower without requiring wider eyes. A shorter nasal region may contribute, although the nose can still be broad or project forwards.

At a smaller angle, check whether the nasal base lies farther down or the outer eye span is limited. Broad cheekbones can surround either arrangement, so a deep internal triangle can occur within a wide face.

A deep triangle containing a tall, narrow nose repeats the vertical emphasis through the centre. A broad nose within that same triangle occupies more space across its lower part and may look substantial in both height and width. Nose height-to-width and nose-to-face width help distinguish those appearances.

A shallow triangle with long eye openings can owe much of its breadth to eye size. If the openings are shorter and widely separated, the space between them contributes more. Comparing eye width with the inner-corner gap explains how the upper span is occupied.

The philtrum determines how far the mouth sits below the triangle's lower point. A shallow eye-nose triangle followed by a long philtrum can still leave a substantial eye-to-mouth distance. A deeper triangle followed by a short philtrum distributes that distance differently.

The angle-difference measurement reports the absolute difference between this angle and the frontal jaw angle. Because it is unsigned, the result gives the size of the difference rather than showing which angle is larger. The original angles are needed to interpret it.

Similar values may create a resemblance between the central triangle and the lower-face taper, but equality can occur with very different shapes. A small difference might join two large angles or two small ones. Look at the marked eye-nose triangle and jaw lines to see whether the centre and lower outline repeat a slope or contrast with each other. A larger difference may simply describe a broader centre above a more tapered lower face.

Pallett and colleagues found that changing central feature spacing affected attractiveness ratings. Zheng and colleagues examined nasal length and width alongside inner-eye spacing. These studies give context for the neighbouring proportions, although neither tests this outer-eye-to-nasal-base angle directly.

During growth, the eye region and nose change at different rates. Increasing nasal height can deepen the triangle, while greater eye span opens it. The final angle reflects how these dimensions develop together, and matching angles can occur in triangles of different overall sizes.

The 85–95° reference describes a triangle whose lower angle is close to a right angle. It provides an easily pictured shape, rather than a preferred range established for these exact landmarks.

Compare the triangle's width and depth separately when interpreting a result outside this interval.