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Konogan BARANTON, Thien Huong NGUYEN, Masaki YOSHIDA, Guillaume GIRAUDET; Comparing V1 between myopes and emmetropes.. Journal of Vision 2014;14(10):686. doi: 10.1167/14.10.686.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction : Beyond their refractive distinction, Myopes and Emmetropes show behavioral differences, especially in the presence of blur. Our study's aim is to compare cortical responses in the primary visual cortex (V1) between the two populations and explore correlations with optometric measurements. Protocol : We studied 21 young adults (18 to 35 years), including 10 Myopes and 11 Emmetropes. The total wavefront aberration with natural pupil diameter is measured for both eyes without correction. Once equipped with their visual correction, they undergo an fMRI exam at 3T. This includes a sequence of retinotopy and stimulation for 18s, viewing natural images or tables of optotypes, either sharp or with a 2 diopter artificial blur. To maintain the subject's attention, a detection task of gradual reversal of blur level was introduced at the end of the stimulation (last 6 seconds). Analysis : Data were processed with BrainVoyager and Matlab. The parts of V1 corresponding to the fovea, the perifovea and 3° of eccentricity, were located for each subject. Then cortical activity was integrated over the static stimulation duration. Values obtained were compared with optometric measures. Results : The main significant correlations are between the mean total wavefront aberration of both eyes (rms) and perifovea. For Myopes correlations are for sharp scenes (left, right and both hemisphere R ² = 0.64, p = 0.01) and sharp optotypes (right and both hemisphere R ² = 0.58, p = 0.01). For Emmetropes correlations are significant only for the left hemisphere activity for sharp optotypes (R ² = 0.46, p = 0.02) and sharp scenes (R ² = 0.38, p = 0.04). Conclusion : The level of cortical activity of V1 corresponding to the perifovea of corrected Myopes remains correlated with the total wavefront aberration, when taking into account both ametropia and pupil diameter. This correlation is much weaker for Emmetropes.
Meeting abstract presented at VSS 2014
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