title: Rotation of retinal vascular arcades and comparison with disc-fovea angle in the assessment of cycloposition.
abstract: OBJECTIVE
  To assess the agreement between disc-fovea angle (DFA) and the retinal vascular arcades rotation to measure cycloposition. Device repeatability and reproducibility between observers were also evaluated.
  
  
  METHODS
  Cycloplegic retinography was taken in 321 eyes of 165 normal patients and repeated in 18 eyes at least 24 h later. Two independent observers used software to determine DFA, vein-related angle (VRA) and artery-related angle (ARA) in every retinography. Mean value of related angle (MRA) (mean value of VRA and ARA) was calculated.
  
  
  RESULTS
  Camera repeatability was good (Intra-class Correlation Coefficient, ICC 0.89). In Bland-Altman analysis, mean VRA, ARA and MRA were 4° to 5° different from DFA (p<0.01). There was poor correlation between DFA and other methods (ICC): DFA versus VRA 0.3, versus ARA 0.4, versus MRA 0.5. Reliability between observers was good in all methods. The multivariate analysis showed no interaction between each method and eye side, sex or observer (p>0.05).
  
  
  CONCLUSIONS
  The rotation of retinal vascular arcades using a first-order approximation technique is no substitute to DFA when assessing torsion in fundus photographs. Of the methods tested, MRA correlated most closely, but DFA remains the gold standard for cycloposition. The rotation of vascular arcades provides a qualitative assessment, particularly in uncertain macular location.
authors.affiliation: Departamento de Óptica II (Optometría y Visión), Facultad de Óptica y Optometría, Universidad Complutense de Madrid, , Madrid, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Piedrahita-Alonso
authors.forename: Alicia
authors.initials: A
authors.lastname: Valverde-Megias
authors.forename: Rosario
authors.initials: R
authors.lastname: Gomez-de-Liano
mesh_terms: D000328:Adult; D005260:Female; D005584:Fovea Centralis / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D009898:Optic Disk / Q000473:pathology*; D010781:Photography / Q000379:methods; D015203:Reproducibility of Results; D012171:Retinal Vessels / Q000002:abnormalities*; D012399:Rotation; D013285:Strabismus / Q000175:diagnosis*
keywords: Anatomy; Imaging; Muscles; Retina