Columella Labial Angle
The nasolabial angle is calculated by first drawing a point to the bottom of the nose (subnasale). From here a line is drawn to the top of the lip (labrale superiorius). An additional line is drawn to the part of the columella which is the most inferior or hanging. The problem with this technique in calculating how much the nose hangs or does not hang is that it does not distinguish nasal tip position from hanging columellas. This is very important from a surgical standpoint in that these two issues are quite different.
First a line is drawn through the Frankfort Horizontal plane. The Frankfort Horizontal is the line from the top of the tragus to the infraorbital rim which is essentially defines what is horizontal on the face. A line is then drawn from the anterior aspect of the nostril to the posterior aspect. An additional line is drawn perpendicular to the Frankfort Horizontal line. The angle created by the vertical line and the anterior to posterior aspect line gives a measure of how much the nose is rotated along the face.
The nasolabial angle derived from the columella tends to overemphasize the impact on the columella and the impact on lip shape. The method which uses the Frankfort Horizontal may have nasal tips appear less rotated. The key factor in any measure is that it serves as a guide. It must be factored with many measurements and most importantly the surgeon and patient’s aesthetic to help create a visually pleasing nasal angle.