June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Magnocellular Visual Pathway Deficit In Dyslexia: Analysis Of Possible Patterns Of Visual Field Alterations Tested With Frequency Doubling Illusion
Author Affiliations & Notes
  • Fernando Avellis
    Section of Ophthalmology, University Hospital of Parma, Parma, Italy
  • Alessandra Dassò
    Service of Childhood Neuropsychiatry, Local Health Unit of Parma - Hospital of Fidenza, Fidenza, Italy
  • Arturo Carta
    Section of Ophthalmology, University Hospital of Parma, Parma, Italy
  • Vincenzo Scorcia
    Ophthalmology, University Of Magna Graecia, Catanzaro, Italy
  • Stefano Gandolfi
    Section of Ophthalmology, University Hospital of Parma, Parma, Italy
  • Footnotes
    Commercial Relationships Fernando Avellis, None; Alessandra Dassò, None; Arturo Carta, None; Vincenzo Scorcia, None; Stefano Gandolfi, SENSIMED (R), ALLERGAN (R), ALCON (R), ALLERGAN (F), ALCON (F), GLAUKOS (F), IVANTIS (F)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 1214. doi:
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      Fernando Avellis, Alessandra Dassò, Arturo Carta, Vincenzo Scorcia, Stefano Gandolfi; Magnocellular Visual Pathway Deficit In Dyslexia: Analysis Of Possible Patterns Of Visual Field Alterations Tested With Frequency Doubling Illusion. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1214.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

To identify a possible visual lack in specific areas of visual field in children with reading disabilities (dyslexia) by exploring the spatial frequency doubling responses characteristic of the magnocellular pathway.

 
Methods
 

Eighteen dislexic subjects and nine controls (mean age 8,4±1,4 years [range, 7-13 years]) consecutively enrolled, were compared on the average of threshold detection for frequency doubling illusion of 5 contiguous retinal sections amog 19 locations of visual field (VF) grouped by 7 topographic patterns: central (CE), superior-nasal (SN), outer superior-temporal (OST), inner inferior-temporal (IIT), inferior-nasal (IN), inner superior-temporal (IST), outer inferior-temporal (OIT). Participants spared from reading comprension difficulties and scored below the cut-off for either speed or accuracy in reading on the MT reading disability test were included in the group of dyslexics. A refractive defect superior than +/-2 Dioptres of spherical equivalent was excluded. Best corrected visual acuity (BVCA) was examined before treatment based on logopedic support. A control group, consisting of children without dislexia was examined as well. The enrolled children were free of any ocular morbidity, as shown by routine ophthalmological evaluation. The visual stimuli were presented on a Humphrey Instruments Frequency Doubling Technology (FDT) Visual Field Instrument: the default settings included measurements of both eyes separately at all 19 VF locations exploring the central 30 degree radius of eccentricity with a full threshold analysis program (N-30).

 
Results
 

Right and left eye average of the thresholds of clusters of 5 contiguous points of VF for each pattern indicated was calculated: the 7 averages of thresholds obtained was compared for each eye between the control and dyslexics groups. For the right and left eye the results indicated a non statistically significant difference between control and affected cases for all patterns except for the patterns CE,OIT,IN of the left eye (P<0,05). The two groups were comparable for loss of fixation, false positive error and false negative error.

 
Conclusions
 

Dyslexic patients may be less sensitive in specific sections of visual field analyzed with FD illusions. This topographic failure may help to confirm that a deficit in magnocellular visual pathway correlate to reading difficulties.

 
Keywords: 757 visual development: infancy and childhood • 758 visual fields • 612 neuro-ophthalmology: diagnosis  
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