title: Computerized photogrammetry used to calculate the brow position index.
abstract: BACKGROUND
  The orbital region is of vital importance to facial expression. Brow ptosis, besides having an impact on facial harmony, is a sign of aging. Various surgical techniques have been developed to increase the efficacy of brow-lift surgery. However, no consensus method exists for an objective measurement of the eyebrow position due to the curvature of the face. Therefore, this study aimed to establish a method for measuring the eyebrow position using computerized photogrammetry.
  
  
  METHODS
  For this study, 20 orbital regions of 10 volunteers were measured by direct anthropometry using a digital caliper and by indirect anthropometry (computerized photogrammetry) using standardized digital photographs. Lines, points, and distances were defined based on the position of the anthropometric landmarks endocanthion and exocanthion and then used to calculate the brow position index (BPI). Statistical analysis was performed using Student's t test with a significance level of 5 %.
  
  
  RESULTS
  The BPI values obtained by computerized photogrammetric measurements did not differ significantly from those obtained by direct anthropometric measurements (p > 0.05). The mean BPI was 84.89 ± 10.30 for the computerized photogrammetric measurements and 85.27 ± 10.67 for the direct anthropometric measurements.
  
  
  CONCLUSIONS
  The BPI defined in this study and obtained by computerized photogrammetry is a reproducible and efficient method for measuring the eyebrow position.
  
  
  METHODS
  This journal requires that authors assign a level of evidence to each article.
authors.affiliation: Division of Plastic Surgery, Universidade Federal de São Paulo, Rua Napoleão de Barros, São Paulo, Brazil.
authors.forename: Naif Thadeu
authors.initials: NT
authors.lastname: Naif-de-Andrade
authors.forename: Bernardo
authors.initials: B
authors.lastname: Hochman
authors.forename: Camila Zirlis
authors.initials: CZ
authors.lastname: Naif-de-Andrade
authors.forename: Lydia Masako
authors.initials: LM
authors.lastname: Ferreira
mesh_terms: D000293:Adolescent; D000328:Adult; D000886:Anthropometry / Q000379:methods; D005138:Eyebrows / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008875:Middle Aged; D010780:Photogrammetry / Q000379:methods; D055815:Young Adult