title: Clinical impairment measures and reading performance in a large age-related macular degeneration group.
abstract: OBJECTIVE
  To investigate the relationship between clinical impairment measures and reading performance in a large population with age-related macular degeneration.
  
  
  METHODS
  The following clinical measures were evaluated on 243 patients with age-related macular degeneration: better eye distance visual acuity (ETDRS chart); threshold near word reading acuity (Bailey-Lovie Word Reading chart); maximum reading speed and critical print size (MNREAD chart); letter contrast sensitivity (Pelli-Robson); and kinetic perimetry (Bjerrum screen) to determine the nearest non-scotomatous point to fovea (NNPF; in degrees) and the central scotoma area (mm2).
  
  
  RESULTS
  Distance acuity correlated well to threshold near word acuity (r = 0.71), but word acuity was usually poorer. Critical print size was strongly related (p < 0.001) to near visual acuity (r2 = 0.31 and beta = 0.47) and was poorer than threshold near word visual acuity by a mean difference of -0.41 (range, -1.10 to 0.34), which represents a mean acuity reserve of 2.5:1. On single regression, distance (p < 0.0001, r2 = 0.35, and beta = -102.37) and near acuities (p < 0.0001, r2 = 0.52, beta = -126.53), critical print size (p = 0.0001, r2 = 19, and beta = 0.002), contrast sensitivity (p < 0.0001, r2 = 19, and beta = 79.47), scotoma size (p = 0.006, r2 = 12, and beta = -0.04), and NNPF (p = 0.001, r2 = 12, and beta = -4.39) were all highly significantly related to reading speed although these predicted only a low percentage of variance. Best prediction of reading speed was obtained on multiple regression, where NNPF and near word acuity explained 60% of the variance (p < 0.0001).
  
  
  CONCLUSIONS
  Optimal prediction of reading speed with clinical parameters appears to be based on the combination of near word acuity and scotoma area, explaining 60% of the variance. Other factors not measured in this study are likely to account for the rest of the prediction.
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Manchester, UK.
authors.forename: Isabel
authors.initials: I
authors.lastname: Cacho
authors.forename: Christine Margaret
authors.initials: CM
authors.lastname: Dickinson
authors.forename: Heather Jane
authors.initials: HJ
authors.lastname: Smith
authors.forename: Robert Anthony
authors.initials: RA
authors.lastname: Harper
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D004410:Dyslexia / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008268:Macular Degeneration / Q000175:diagnosis / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011932:Reading; D014786:Vision Disorders / Q000175:diagnosis / Q000503:physiopathology*; D014787:Vision Tests; D014792:Visual Acuity / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*