Background: Dyslexia has been associated with atypical eye-movement control, but whether such differences arise only during reading or reflect broader oculomotor control remains debated.
Methods: We compared 40 children with dyslexia and 40 age/sex matched controls (8-12 years). Binocular eye movements were recorded with infrared video-oculography (VOG) using a clinical VNG platform's oculomotor module. Participants performed a random-step horizontal saccade task (targets at ±15° and ±20° from midline (step amplitudes 5°-40°); pseudo-random 3-4 s intervals). Saccades were detected with manufacturer thresholds (40°/s, 800°/s2). Primary outcomes were peak velocity (°/s), accuracy (%) and latency (ms); optokinetic responses (OKR) were analysed for each eye, and we report the interocular OKR difference (%). Trials with blinks/track-loss were excluded a priori.
Results: Compared with controls, children with dyslexia showed slower saccades (307.5°/s vs. 453.5°/s), lower accuracy (71.5% vs. 98.5%) and longer latency (260.0 vs. 131.5 ms), all p < 0.001. Right-eye OKR was reduced, whereas left-eye OKR did not differ significantly, and the interocular OKR difference was significantly larger in dyslexia. These group differences remained significant after adjustment for relevant socio-demographic covariates.
Conclusions: Children with dyslexia exhibited robust oculomotor differences during a nonreading task, consistent with altered visually guided saccade control. These results are associative rather than causal and suggest that oculomotor measures may provide complementary insight into dyslexia.
Keywords: dyslexia; eye movement; oculomotor control; optokinetic response; reading disability; saccades.
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