Ophthalmic Findings in Greek Dyslexic Children

Abstract

Purpose: : Due to the involvement of visual pathways in dyslexia, visual functions and visual problems affecting reading ability were subject to investigation. Binocular vision dysfunctions such as accommodation, vergence function and ocular motility have been shown to adversely affect the reading performance and sustainability. The present study investigates the visual performance of Greek dyslexic children. Moreover it aims to examine if findings from previous studies can accommodate those of the Greek language despite the differences of reading performance in Greek and other languages with or without transparent orthography.

Methods: : Thirty four children (17 formally diagnosed with dyslexia and 17 age-matched normal readers) all native speakers of Greek participated in this study. All had normal vision or vision corrected to normal with glasses. All children were recruited from the same state mainstream schools of Heraklion, Crete. The mean age of the dyslexic and non-dyslexic groups was 11.50 years (SD 1.51) and 12.14 years (SD 0.95), respectively. The children who met the inclusion criteria for dyslexia were diagnosed at the Centre for Mental Health and Research (accredited diagnostic centre for special educational needs in Heraklion. All the children had an eye examination of ocular dominance, refraction, horizontal and vertical phorias for distance and near, horizontal vergence reserve for distance and near, cover test, worth 4-dot test for distance and near, color vision, tests of accommodative function and convergence amplitude.

Results: : Highly statistical significant difference was found only in vergence reserve for distance and near where 94.11% of the dyslexic children had values lower than the standard that represents the zone of clear, single binocular vision and in ocular dominance where 82,35% of the dyslexic group was left eye dominant as opposed to only 11,76 of the control group.

Conclusions: : Visual impairment of Greek dyslexics is similar to that of dyslexic readers of other languages concerning the vergence reserves. However they present strong left eye dominance although 58,82% of them are ambidextrous with prevalent right hand. Ophthalmic factors should be considered part of the dyslexic syndrome and early visual function analysis can play a role in its early diagnosis.

Keywords: vergence • ocular motor control • accommodation