title: Optokinetic therapy improves text reading in patients with hemianopic alexia: a controlled trial.
abstract: OBJECTIVE
  An acquired right-sided homonymous hemianopia can result in slowed left-to-right text reading, called hemianopic alexia (HA). Patients with HA lack essential visual information to help guide ensuing reading fixations. We tested two hypotheses: first, that practice with a visual rehabilitation method that induced small-field optokinetic nystagmus (OKN) would improve reading speeds in patients with HA when compared to a sham visual rehabilitation therapy; second, that this therapy would preferentially affect reading saccades into the blind field.
  
  
  METHODS
  Nineteen patients with HA were entered into a two-armed study with two therapy blocks in each arm: one group practiced reading moving text (MT) that scrolled from right to left daily for two 4-week blocks (Group1), while the other had sham therapy (spot the difference) for the first block and then crossed over to MT for the second.
  
  
  RESULTS
  Group 1 showed significant improvements in static text reading speed over both therapy blocks (18% improvement), while Group 2 did not significantly improve over the first block (5% improvement) but did when they crossed over to the MT block (23% improvement). MT therapy was associated with a direction-specific effect on saccadic amplitude for rightward but not leftward reading saccades.
  
  
  CONCLUSIONS
  Optokinetic nystagmus inducing therapy preferentially affects reading saccades in the direction of the induced (involuntary) saccadic component. This is the first study to demonstrate the effectiveness of a specific eye movement based therapy in patients with hemianopic alexia (HA) in the context of a therapy-controlled trial. A free Web-based version of the therapy used in this study is available online to suitable patients with HA.
authors.affiliation: Department of Clinical Neurosciences, Royal Free Hospital and University College Medical School, London, UK.
authors.forename: G A
authors.initials: GA
authors.lastname: Spitzyna
authors.forename: R J S
authors.initials: RJ
authors.lastname: Wise
authors.forename: S A
authors.initials: SA
authors.lastname: McDonald
authors.forename: G T
authors.initials: GT
authors.lastname: Plant
authors.forename: D
authors.initials: D
authors.lastname: Kidd
authors.forename: H
authors.initials: H
authors.lastname: Crewes
authors.forename: A P
authors.initials: AP
authors.lastname: Leff
mesh_terms: D000328:Adult; D000368:Aged; D002675:Child, Preschool; D005260:Female; D006423:Hemianopsia / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017120:Nystagmus, Optokinetic / Q000502:physiology*; D011932:Reading; D012438:Saccades / Q000502:physiology*; D014794:Visual Fields