title: Eye movements and reading in glaucoma: observations on patients with advanced visual field loss.
abstract: OBJECTIVE
  To investigate the relationship between reading speed and eye movements in patients with advanced glaucomatous visual field (VF) defects and age-similar visually healthy people.
  
  
  METHODS
  Eighteen patients with advanced bilateral VF defects (mean age: 71, standard deviation [SD]: 7 years) and 39 controls (mean age: 67, SD: 8 years) had reading speed measured using short passages of text on a computer set-up incorporating eye tracking. Scanpaths were plotted and analysed from these experiments to derive measures of 'perceptual span' (total number of letters read per number of saccades) and 'text saturation' (the distance between the first and last fixation on lines of text). Another eye movement measure, termed 'saccadic frequency' (total number of saccades made to read a single word), was derived from a separate lexical decision task, where words were presented in isolation.
  
  
  RESULTS
  Significant linear association was demonstrated between perceptual span and reading speed in patients (R (2) = 0.42) and controls (R (2) = 0.56). Linear association between saccadic frequency during the LDT and reading speed was also found in patients (R (2) = 0.42), but not in controls (R (2) = 0.02). Patients also exhibited greater average text saturation than controls (P = 0.004).
  
  
  CONCLUSIONS
  Some, but not all, patients with advanced VF defects read slower than controls using short text passages. Differences in eye movement behaviour may partly account for this variability in patients. These patients were shown to saturate lines of text more during reading, which may explain previously-reported difficulties with sustained reading.
authors: Department of Optometry and Visual Science, City University London, Northampton Square, London, EC1V 0HB, UK.
authors: Robyn
authors: R
authors: Burton
authors: Nicholas D
authors: ND
authors: Smith
authors: David P
authors: DP
authors: Crabb
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005901:Glaucoma / Q000503:physiopathology*; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D011932:Reading; D012438:Saccades / Q000502:physiology*; D014786:Vision Disorders / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology*