Developmental dyslexia and vision

Abstract

Developmental dyslexia affects almost 10% of school-aged children and represents a significant public health problem. Its etiology is unknown. The consistent presence of phonological difficulties combined with an inability to manipulate language sounds and the grapheme–phoneme conversion is widely acknowledged. Numerous scientific studies have also documented the presence of eye movement anomalies and deficits of perception of low contrast, low spatial frequency, and high frequency temporal visual information in dyslexics. Anomalies of visual attention with short visual attention spans have also been demonstrated in a large number of cases. Spatial orientation is also affected in dyslexics who manifest a preference for spatial attention to the right. This asymmetry may be so pronounced that it leads to a veritable neglect of space on the left side. The evaluation of treatments proposed to dyslexics whether speech or oriented towards the visual anomalies remains fragmentary. The advent of new explanatory theories, notably cerebellar, magnocellular, or proprioceptive, is an incentive for ophthalmologists to enter the world of multimodal cognition given the importance of the eye’s visual input.

Ophthalmic Abnormalities and Reading Impairment

“…18 A review of the literature in 2013 found that poor perception of low contrast was associated with dyslexia. 24 These results were based on small school-based studies, with participants generally described as having "reading difficulties" rather than specifically dyslexia, and were not corroborated by the current study. …”

“…Previously literature reviews in general have been based on school-based studies involving small numbers of children and controls. 24 The ALSPAC study took place in a defined geographic area and was comparable with the United Kingdom as a whole in the 1991 census; however, the number of nonwhite families in ALSPAC was disproportionately small. 36 Noncycloplegic refraction was used to define refractive error.…”

“…2,16,18,[20][21][22][23] A descriptive review of 114 articles published from 2000 to 2012 found that eye movement anomalies, visual contrast deficits, and pseudoneglect were the main ophthalmic features associated with dyslexia. 24 It has been hypothesized that the abnormalities in eye movements are potentially the result, not the cause, of the condition. 10 This study aims to investigate the association between DSM-V classified specific learning disorder with reading impairment and a range of ophthalmic abnormalities assessed at age 7, based on data from a large, prospectively collected UK birth cohort.…”

Reinterpretando la Dislexia. Propuesta diferenciadora para una neurodidáctica inclusiva

“…En este proceso la atención (guiada desde arriba) a estas dimensiones espaciotemporales por parte de las áreas primarias auditivas y visuales modula las neuronas de las áreas sensoriales primarias (abajo) que envían la información procesada a áreas corticales superiores para su correcto almacenamiento, lo que facilita el reconocimiento ante el mismo estímulo en el futuro. La atención espacial afecta no solo a la habilidad para detectar el estímulo, sino también para representar mentalmente este estimulo (Quercia, Feiss y Michel, 2013) y, por tanto, para almacenarlo y recuperarlo.…”

“…Este déficit audiovisual para el procesamiento de la información espacio-temporal es la causa de un lento reconocimiento de las letras y una pobre habilidad para secuenciar las letras y sus sonidos que, a su vez, deriva de un déficit en sincronización sensorial (sensory timing) de los imputs visuales durante la lectura y los sonidos de la palabra cuando se escuchan, esto es, un déficit en el procesamiento temporal (Stein, 2018). El déficit en el procesamiento temporal del habla oral también es explicado por la por la teoría magnocelular, puesto que este contribuye a la rápida integración de la información visual mientras leemos permitiendo un procesamiento eficiente, sincrónico, de la información visual espacial y temporal y puede intervenir con un papel equivalente con la información auditiva (Quercia, Feiss y Michel, 2013).…”