Abstract
Abstract: :
Purpose: Comparison between clinically tested visual loss and cortical activation retrieved in functional MRI. Methods: We performed a prospective evaluation in 8 patients with neovascular age-related macular disease (ARMD), from 67 to 82 years of age. Clinical examinations evaluated the remaining visual acuity, the macular destruction and the new fixation point (SLO). In fMRI, a sequential paradigm alternated rest and activation phases, with white flashes at 2 Hz stimulating the central retina of each eye (10° width). Results: The cortical activation after monocular stimulations showed : 1/ a restricted activation of macular dedicated striate cortex for ARMD eye; 2/ no linear correlation between cortical activations and clinical visual worsening; 3/ a cortical activation depending on the macular destruction width and the effective fixation point. Conclusion: There is no linear correlation for cortical activation and clinical findings. The macular destruction is reflected by a restricted activation of macular-dedicated striate cortex, but important cortical activations may be found, even in subjects with lowest visual acuities. This suggest the functional importance of some macular preserved areas. The eccentricity of new retinal fixation points may induce lateralization of the visual fields, corresponding to asymmetric cortical activations. Comparisons between retinal and cortical activations highlight alternative modalities in cortical analysis of visual stimulation, for a better handling of ARMD reeducation.
Keywords: 308 age-related macular degeneration • 430 imaging/image analysis: clinical • 459 low vision