title: [Digital analysis of the optic disc with fundus camera: a study of variability].
abstract: OBJECTIVE
  To determine the variability of the measurements of the optic discs applying digital analysis techniques and working with a digital camera available for clinical use.
  
  
  METHODS
  We used a fundus camera with telecentric optic system (Zeiss FF 450 IR plus) and a 3 CCD high resolution colour video camera. We used a digital analysis system (Visupac 3.2.1) equipped with measurement systems. The images were studied by three observers with different degrees of experience who analysed the optic disc diameters (horizontal and vertical) and the total optic disc area. 180 measurements were made.
  
  
  RESULTS
  The coefficient of total variability for the studied parameters presented a range from 1.04 to 2.08%. The variability attributable to the observer was found to be lower in the case of the observer with a higher imaging analysis experience, with a range from 0.42 to 1.17% for the lineal measurements (vertical and horizontal diameters) and from 0.60 to 2.11% for measurements of the area (total optic disc area).
  
  
  CONCLUSIONS
  The digital analysis of optic disc images obtained with conventional fundus cameras, equipped with telecentric optic systems, allows reproducible measures and can be easily employed in clinical practice.
authors.affiliation: Unidad de Oftalmología, Fundación Hospital Alcorcón, Madrid. pgili@fhalcorcon.es
authors.forename: P
authors.initials: P
authors.lastname: Gili Manzanaro
authors.forename: C
authors.initials: C
authors.lastname: Carrasco Font
authors.forename: J C
authors.initials: JC
authors.lastname: Martín Rodrigo
authors.forename: J
authors.initials: J
authors.lastname: Yangüela Rodilla
authors.forename: A
authors.initials: A
authors.lastname: Arias Puente
mesh_terms: D000703:Analog-Digital Conversion; D000886:Anthropometry / Q000295:instrumentation / Q000379:methods*; D005654:Fundus Oculi; D005901:Glaucoma / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D015588:Observer Variation; D019721:Ophthalmoscopes; D009898:Optic Disk / Q000648:ultrastructure*; D010781:Photography / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D014741:Video Recording / Q000295:instrumentation / Q000379:methods