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M. G. Thomas, F. A. Proudlock, R. J. McLean, I. Gottlob; Voluntary Modulation of Involuntary Eye Movements During Reading. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2833.
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© ARVO (1962-2015); The Authors (2016-present)
To understand how individuals with infantile nystagmus read in view of the sensory motor deficits associated with this condition.
Eye movement recordings were carried out in healthy (n=7), IIN (n=14) and albino (n=10) volunteers during reading for distance (1.2m) and near (0.33m) at five gaze positions (-20°, -10°, 0°, 10° and 20°). Reading speeds (RS) and beating pattern were derived from these recordings. Visual acuity (VA) was also measured over the same eccentricities and distances. The nystagmus volunteers underwent a further fixational task over the same eccentricities to derive the waveform characteristics of nystagmus.
RS were significantly (p<0.05) slower in nystagmus volunteers when compared to age and IQ matched controls. VA is a good predictor of RS in IIN (R2 = 0.48, p<0.05) but not albinism (R2 = 0.08, p<0.05). Right beating waveform was associated with faster RS and left beating with slower RS (p<0.05). Intensity had a significant effect on RS in IIN (p<0.05); however, it was a poor predictor of RS (R2 = 0.12). There was a change in the nystagmus waveform when fixating a target and when reading. During reading around the null point most volunteers used a pendular waveform which was modulated by the quick phases while during fixation different waveforms were encountered. The voluntary modulation of the nystagmus is further substantiated by the difference in frequency between the fixational task and the reading task.
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