title: Intersession repeatability of contrast sensitivity scores in age-related macular degeneration.
abstract: OBJECTIVE
  To describe the intersession repeatability of contrast sensitivity (CS) measurement using Pelli-Robson charts in patients with age-related macular degeneration.
  
  
  METHODS
  Repeatability was calculated from three measurements of CS over a 12-week period using a standardized protocol in 107 nontreated eyes of 107 patients with age-related macular degeneration who were enrolled in an ongoing clinical trial.
  
  
  RESULTS
  Data from 91 patients were included in the analysis, with a 95% coefficient of repeatability of 7 letters (0.35 log CS), ranging from 6 letters for 32 eyes with drusen only to 8 letters for patients with late AMD (macular scars or geographic atrophy). Three (3%) of these stable patients had an apparent six or more letter reduction in contrast sensitivity at the week 1 visit compared with baseline.
  
  
  CONCLUSIONS
  There is a high intersession test-retest variability of Pelli-Robson CS scores in patients with AMD, with implications for AMD clinical trial design. Although a change criterion of six or more letters may be an adequate end point in clinical trials for patients with early AMD, a larger change criterion may be necessary for clinical trials of patients with late AMD.
authors.affiliation: Moorfields Eye Hospital, London, United Kingdom.
authors.forename: Praveen J
authors.initials: PJ
authors.lastname: Patel
authors.forename: Fred K
authors.initials: FK
authors.lastname: Chen
authors.forename: Gary S
authors.initials: GS
authors.lastname: Rubin
authors.forename: Adnan
authors.initials: A
authors.lastname: Tufail
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D020533:Angiogenesis Inhibitors / Q000627:therapeutic use; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized; D000068258:Bevacizumab; D015350:Contrast Sensitivity / Q000502:physiology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors; D014787:Vision Tests / Q000592:standards*
chemical_list: D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D042461:Vascular Endothelial Growth Factor A; D000068258:Bevacizumab