title: Coherent motion threshold measurements for M-cell deficit differ for above- and below-average readers.
abstract: BACKGROUND
  Research during the past 20 years has influenced the management of diagnosis and treatment of children identified as having learning-related vision problems. The intent of this study is to determine whether coherent motion threshold testing can distinguish better-than-average non-disabled (ND) readers from those who are moderately reading disabled (RD) among sixth-grade students.
  
  
  METHODS
  A sample of 23 better-than-average non-disabled readers (> or = 80th percentile) and 27 moderately disabled readers (< or = 32nd percentile) were identified using a standardized reading comprehension test. Each participant was tested for coherent motion threshold. Previous psychophysical and fMRI research with adults suggests that coherent motion threshold is a valid measure of magnocellular (M-cell) integrity.
  
  
  RESULTS
  The average of two coherent motion threshold trials was significantly greater for moderately reading disabled subjects than for above-average readers (p < 0.01). The mean threshold percentage of dots required to observe lateral motion was 9.2% for moderately reading disabled readers and 4.6% for superior readers (p = 0.001).
  
  
  CONCLUSIONS
  The outcome of this preliminary study provides an efficient procedure to identify sixth-grade students whose reading disability may be associated with an M-cell deficit. Our previous investigations involving visual processing, visual attention, and oculomotor therapy have resulted in significant improvements in reading comprehension, visual attention, and eye movements. It remains to be demonstrated whether vision therapy has an impact on the M-cell deficit, as measured with coherent motion threshold testing for moderately disabled readers.
authors.affiliation: Schnurmacher Institute for Vision Research, College of Optometry, State University of New York, New York, New York 10036, USA. hsolan@sunyopt.edu
authors.forename: Harold A
authors.initials: HA
authors.lastname: Solan
authors.forename: Peter C
authors.initials: PC
authors.lastname: Hansen
authors.forename: John
authors.initials: J
authors.lastname: Shelley-Tremblay
authors.forename: Anthony
authors.initials: A
authors.lastname: Ficarra
mesh_terms: D016022:Case-Control Studies; D002648:Child; D004410:Dyslexia / Q000175:diagnosis* / Q000473:pathology / Q000523:psychology*; D006801:Humans; D009039:Motion Perception; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012684:Sensory Thresholds; D012720:Severity of Illness Index; D014796:Visual Perception