Answer:
Nasal proportions and relationships exist that are helpful in evaluating the patient for rhinoplasty. The relationships are not meant to be absolute, but rather form a foundation for analyzing the face. Some of these proportions are as follows:
- the distance from the infraorbital rim to the base of the nose is equal to the width of the nasal base and ½ the distance of the middle third of the face (brow to nasal base).
- nasal length (radix to tip or RT) should equal the distance from stomion to menton which equals 1.6 x TS (tip to stomion).
- ideal tip projection (alar crease to tip) equals 0.66 x ideal nasal length (RT).
- a line from the midglabellar area to the menton should bisect the nasal bridge, the nasal tip, and Cupids bow.
- the nasal dorsum should be outlined by two slightly curved divergent lines extending from the medial supraciliary ridges to the tip defining points.
- the width of the bony base is approximately equal to 80% of the alar base.
- the width of the alar base is equal to the intercanthal distance or one eye width.
- the alar rims should have a slight outward flare in an inferior direction.
- lines connecting the tip defining points, the supratip break area, and the columellar lobular angle form two equilateral triangles.
- a line outlining the alar rims and columella resembles a gull in gentle flight.
- with the eyes in frontal gaze, the nasofrontal angle lies at a level between the upper eyelashes and the supratarsal crease.
- the nasal dorsum, in women, lies approximately 2 mm behind and parallel to a line from just above the nasofrontal angle to the tip defining points. In men, the dorsum is slightly higher.
- 50-60% of the tip lies anterior to a vertical line drawn adjacent to the most projecting portion of a normally positioned upper lip.
- tip projection equals alar base width.
- tip rotation is determined by the degree of the nasolabial angle, measured as the angle between vertical and a line drawn through the most anterior and posterior edges of the nostrils (normal 95-100 degrees in women and 90-95 degrees in men) (nasolabial angle is not the same as columellar labial angle).
- the columellar-lobular angle is approximately 45 degrees.
- on basal view, the outline of the nasal base forms an equilateral triangle; the lobular to nostril ratio is 1:2.
- the upper lip projects 2 mm more than the lower lip, and in women, the chin lies slightly posterior to the lower lip; slightly stronger in men.
- the distance from the mandibular angle to the menton is ½ the distance from the menton to the natural hairline.