title: Intraobserver repeatability of macula measurements by confocal scanning laser tomography.
abstract: OBJECTIVE
  To assess the repeatability of macula measurements provided by the Heidelberg Retina Tomograph II (HRT II) in normal subjects, patients with diabetic macular edema (DME), and patients with choroidal neovascularization (CNV).
  
  
  METHODS
  Prospective, observational case.
  
  
  METHODS
  
  
  
  METHODS
  Institutional-based study.
  
  
  METHODS
  Ten normal eyes, 14 eyes with DME, and 14 eyes with CNV.
  
  
  METHODS
  Three scans within a single day. An additional three scans of each of the 10 normal eyes on a different day.
  
  
  METHODS
  Bland and Altman analysis for a 0.25 mm, 0.50 mm, and 0.75 mm radius circle.
  
  
  RESULTS
  Variability and repeatability of the measurements were not related to circle size for either group of patients. Coefficient of variability values of the normal group and a 0.50-mm radius circle were 17%, 5.7%, and 6.1% for mean surface height, signal width, and edema index, respectively. The corresponding values were 15.6%, 10%, and 10% for the DME group, and 10.5%, 7.4%, and 8.5% for the CNV group. The 95% confidence interval of the difference between single observations across days of the normal group was +/-106 microm, +/-80 microm, and +/-0.10 for mean surface height, signal width, and edema index, respectively. When three scans were combined, the corresponding values were +/-61.5 microm, +/-46.7 microm, and +/-0.06.
  
  
  CONCLUSIONS
  The repeatability and variability of measurements of normal subjects, patients with DME, and patients with CNV were determined. Differences between the three groups exist and are important for diagnosing a pathologic condition or measuring the effect of various treatments.
authors.affiliation: VEIC, Department of Ophthalmology, School of Medicine, University of Crete, Heraklion, Greece. apallik@med.uoc.gr
authors.forename: Aristophanis
authors.initials: A
authors.lastname: Pallikaris
authors.forename: Dimitra
authors.initials: D
authors.lastname: Skondra
authors.forename: Miltiadis
authors.initials: M
authors.lastname: Tsilimbaris
mesh_terms: D000328:Adult; D000368:Aged; D020256:Choroidal Neovascularization / Q000175:diagnosis*; D016001:Confidence Intervals; D003930:Diabetic Retinopathy / Q000175:diagnosis*; D006801:Humans; D007834:Lasers; D008266:Macula Lutea / Q000473:pathology*; D008269:Macular Edema / Q000175:diagnosis*; D008875:Middle Aged; D015588:Observer Variation; D019721:Ophthalmoscopes / Q000592:standards*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity