Visual function deficits in dyslexic children: a case-control study

To compare the ophthalmic findings between dyslexic and non-dyslexic children aged 7-10 years.

A matched case-control study was conducted on 32 dyslexic children as a case group and 32 non-dyslexics as a control group. Both groups underwent complete ophthalmic examinations to measure corrected distance visual acuity, refractive errors, latent and manifest deviations, stereoacuity, near point of accommodation (NPA), and contrast sensitivity (CS).

The mean age of the participants in our study was 8.1 ± 0.8 (range 7-10) years. Both dyslexic and non-dyslexic groups consisted of 17(53.1%) boys and 15(46.9%) girls. There was no significant difference in visual functions (P > 0.05) except for stereoacuity and contrast sensitivity between the two groups. Contrast sensitivity (CS) was decreased and aggravated in dyslexics versus controls. The mean score of binocular CS in the case and control group was 115.8 ± 40.6 and 175.6 ± 44.3 cycle per degree, respectively (P < 0.001). Notably, stereoacuity was increased in dyslexics versus controls (94.2 ± 73.6 vs. 60.94 ± 12.01 s/arc, P = 0.017).

Dyslexic children exhibited decreased contrast sensitivity and impaired stereoacuity compared to controls. These findings support the theory of magnocellular system deficits in dyslexia. Further research is required to elucidate the role of contrast sensitivity and its impact on dyslexic vision.