The lateral brow: position in relation to age, gender, and ethnicity

Abstract

Purpose: Despite multiple studies regarding modes of eyebrow measurement and movement over time, the lateral aspect of the brow has been relatively ignored in the literature. Therefore, we arranged a study of the most lateral aspect of the eyebrow; in doing so, we hoped to ascertain the most practical line or angle of measurement.

Methods: In this cross-sectional study, adults age 18 years and older with no history of congenital or acquired periorbital or orbital pathology or surgery, brow tattooing or heavy plucking, phthisis, or strabismus were measured using a combination of in-office metrics and computer analysis. Subjects were asked to identify their ethnicity and country of origin. Models of age, gender, and ethnicity were created.

Results: One thousand twenty-four subjects were included (1,944 eyes). Measurements of nasal ala to lateral brow (NALB), lateral brow plumb line (LBPL; the vertical line between the tail of the brow and a horizontal line extending from the lateral canthus), and angle from the midbrow to the lateral brow tail showed statistically significant decline over time. The angle and LBPL varied mostly by ethnicity. The angle narrowed approximately 3° per 20 years, while the LBPL fell approximately 2.5 mm per 20 years. The NALB varied most by age and fell approximately 3 mm per 20 years.

Conclusions: The lateral tail of the brow descends with age. Measurements of its location and rate of change vary between genders and within ethnic groups. Two easily measured values-NALB and LBPL-can be used for preoperative planning and postoperative documentation.

Figure 1

Clinical measurements. Mid-pupil to upper lid margin (MRD1) is shown in white; mid- pupil to mid-brow is shown in gray; nasal ala to lateral brow tail is shown in interrupted black; and “lateral brow plumb line,” as defined by the vertical line between the lateral tail of the brow and a horizontal line extending from the lateral canthus, is shown in thick black.

Figure 2

Angle analysis. Computer analysis of facial photographs allowed for the calculation of the angle formed by the line from mid-pupil to mid-brow and a line from the mid-brow to the lateral brow.

Figure 3

Gendered averages per 20-year age group of mid-pupil to upper lid margin (MRD1). Females started off with slightly higher MRD1 in our subjects, but approached a common average of 3.1mm by the oldest age group. Mm refers to millimeter.

Figure 4

The gendered averages per 20-year age group of mid-pupil to mid-brow in our subjects. Females had a higher central brow by approximately 3mm, which was preserved throughout the age groups. Both males and females have a slight decrease in average measurements over time. Mm refers to millimeter.

Figure 5

Nasal ala to lateral brow. The graph on the left shows the gendered averages per 20-year age group in our subjects, and demonstrates the relatively similar averages in both genders. The graph on the right shows the similar decline over time in all ethnicities. There was a trend towards a slightly greater decrease in this measurement with time among females compared with males in each ethnic group. Mm refers to millimeter.

Figure 6

Lateral brow plumb line. The graph on the left shows the gendered averages per 20-year age group in our subjects, which show relatively consistent rates of decline. Females consistently had higher tails of the lateral brow with respect to the lateral canthus than their age-match male counterparts by approximately 4mm. The graph on the right shows a similar clustering of male and female groups, with the exception of Black subjects, who generally had higher measurements than their peers. Mm refers to millimeter.

Figure 7

Angle from mid-brow to lateral brow tail. The graph on the left shows the gendered averages per 20-year age group in our subjects, and demonstrates the similar measurements in male and female groups. Both groups’ measurements decline with age, indicating a descent of the lateral brow with respect to the central brow with increasing age. The graph on the right shows the angle trendline divided into gendered ethnic groups, of which both Hispanic female subgroups had slower rate of angle reduction than their peers, whereas both Hispanic male subgroups had a faster rate than their peers.