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L. Hoffart, J. Conrath, F. Galland, N. Wotawa, F. Chavane, E. Castet, B. Ridings, G.S. Masson; Cortical Effects of Revertible Scotomas in Central Serous Chorioretinopathy . Invest. Ophthalmol. Vis. Sci. 2006;47(13):800.
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We used functional magnetic resonance imaging (fMRI) to map the retinotopic organization of human cortical areas in patients with central serous chorioretinopathy (CSCR) and to measure the localization and surface of the cortical projections of their central visual scotoma
The First set of experiments were run on 3 patients with acute CSCR. Retinotopic maps were first reconstructed using classical mapping techniques. Second, a block paradigm consisting of a grey background alternating with a fullfield, flickering checkerboard was used to stimulate the complete central (19.5°) visual field. Subjects were asked to fixate with the involved eye a central cross and to report transient colour changes of the latter at random intervals, ensuring that they maintained fixation and attention at the center of the visual field. A Brucker 3T scanner equiped with head coil and custom optical system was used to acquire sets of echo–planar images of 20 occipital coronal slices within a RT of 2111msec and an 8 mm3 voxel resolution. Surface models of each subject’s occipital lobes were constructed using Brainvisa software from a sagital T1 weighted image with a 1mm3 voxel resolution. The cortical models were then inflated to get unfolded surfaces. Statistical analyses of the functional data were made through General Linear Models under SPM99, and the responses amplitudes were finally assigned to the cortical reconstructed surfaces.Unilateral central visual scotoma of each patient was characterized in radius, eccentricity and surface by microperimetry.
At this stage of our study, we only could perform fMRI sessions at the acute stage of CSCR. With our quick retinotopic cortical areas mapping method, we identified the cortical projections of each central scotoma and confirmed their relations by quantitative analysis: the measured cortical positions and surfaces of the inactivated cortical zones were compared with the known values of radius, eccentricity and surface of scotomas in the visual field. With further fMRI sessions in these patients, after recovery of central visual field, we would be able to compare retinotopic maps and to characterize cortical plasticity.
We used sequential fMRI sessions to study cortical plasticity of visual areas in patients with central serous chorioretinopathy.
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