African Vision and Eye Health (Dec 2011)
A comparison of the visual status of dyslexic and non-dyslexic schoolchildren in Durban, South Africa
Abstract
Background: Reading difficulties constitute an impediment to the learning process and in the educational achievement of a child. Consequently, several studies examined the visual status of dyslexic children in the Caucasian populations. Such studies are lacking in the African populations. Aim: To determine the prevalence of vision defects and investigate if there is an association between dyslexia and vision in a South African population of dyslexic school children. Methods: This comparative study assessed the visual function of 62 children (31 dyslexic and 31 normally-reading children), mean age 13 ± 1.42 years and 11.90 ± 0.93 years respectively. The participants were matched for gender, race and socio-economic status. The visual functions evaluated and the techniques used were: visual acuity (LogMAR acuity chart), refraction (static retinos-copy), ocular alignment (cover test) near point of convergence (RAF rule), accommodation facility (± 2 D flipper lenses), amplitude of accommodation (push-up method) relative accommodation (trial lenses) accommodation posture (monocular estimation technique) and vergence reserves (prism bars). Results: In the following, results are provided for the dyslexic versus control: Refractive errors: (hyperopia 6.5% vs 3%,) (myopia 6.5% vs 6.5%), (astigmatism 10% vs 13%), (anisometropia 6.5% vs 6.5%) (amblyopia 6.5% vs 0%), (remote NPC 33% vs 48%) (esophoria at near 3% vs 0%) (exophoria at near 9.5% vs 0%), (accommodative infacility at near 54% vs 33%), lag of accommodation 39.28% vs 41,93%, (poor positive fusional amplitude at near, 25% vs 16%). Only the binocular accommodative facility at near was significantly associated with dyslexia (p=0.027). Conclusion: The prevalence of vision defects was similar between the dyslexic and non-dyslexic participants, which suggest that an association between dyslexia and vision variables investigated, cannot be inferred. This study provides a research perspective on the prevalence of vision defects in a Black South African population of dyslexic children and has clinical relevance and implications for the assessment, detection and management of vision anomalies in dyslexic schoolchildren. (S Afr Optom 2011 70(1) 29-43)
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