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Fatema F. Ghasia, Aasef G. Shaikh; Uncorrected Myopic Refractive Error Increases Microsaccade Amplitude. Invest. Ophthalmol. Vis. Sci. 2015;56(4):2531-2535. doi: https://doi.org/10.1167/iovs.14-15882.
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© ARVO (1962-2015); The Authors (2016-present)
Human brain generates miniature eye movements, such as microsaccades, to counteract image fading due to visual adaptation. Generation of microsaccade relies on the amount of retinal error or acuity demand for a desired visual task. The goal of this study was to assess the influence of visual blur, induced by uncorrected refractive error on microsaccades and saccades.
Ten subjects with myopia held their gaze on a visual target during two experiment conditions: corrected refractive error and uncorrected refractive error. Eye movements were measured with high-resolution video oculography under binocular viewing conditions during both tasks. Gaze holding function, microsaccades, and visually guided saccades were analyzed and compared during both tasks.
We found an increase in the amplitude of microsaccades in the presence of uncorrected refractive error, but the microsaccade frequency and velocity remained unchanged. The microsaccade amplitude systematically increased with an increase in uncorrected refractive error. The main sequence relationship relating the saccade amplitude with respective peak velocity was not significantly different between two conditions. The onset latency, peak velocities, and accuracy of visually guided saccades also were unchanged between the two conditions.
These results suggest that visual blur, hence the precision of an image on the fovea, has an important role in calibrating the amplitude of fixational eye movements, such as microsaccades.
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