Visual cortex activation in patients with stargardt disease

PURPOSE. Primary visual cortex (PVC) contains a retinotopic map in which the central visual field (CVF) is highly magnified compared to the peripheral field. Several studies have used functional magnetic resonance imaging (fMRI) in patients with macular degeneration to assess the reorganization of visual processing in relationship with the development of extrafoveal preferred retinal locus (PRL). We evaluated the functional response in PVC and its correlation with retinal parameters in patients with Stargardt disease due to ABCA4 mutations (STGD1). METHODS. Twenty-four STGD1 patients underwent best-corrected visual acuity, full-field standard electroretinogram (ERG), optical coherence tomography, and microperimetry. Furthermore, patients underwent fMRI to assess cerebral activation during visual stimulation by a flickering checkerboard in four PVC subdivisions, corresponding to 0° to 5° (V1), 5° to 10° (V2), 10° to 15° (V3), and 15° to 40° (V4) of CVF. RESULTS. Higher ERG responses were significantly (P < 0.0125) associated with larger functional cerebral response in V1, V2, and V3 subdivisions. Moreover, larger retinal pigment epithelium atrophy area was significantly (P < 0.0125) associated with smaller PVC activation in V2 and V3 subdivisions. Larger activation in V1 subdivision was significantly (P = 0.001) associated with higher mean macular sensitivity and smaller dense scotoma size. Finally, our results showed reduced activation in V2 and V3 with increased PRL eccentricity. CONCLUSIONS. Our study, for the first time in the literature, showed stronger PVC activation in STGD1 patients with a more preserved retinal function and macular structure. Furthermore, our study data strongly suggest that the evaluation of neuronal reorganization could be performed by considering only retinal parameters, particularly ERG responses.

PURPOSE. Primary visual cortex (PVC) contains a retinotopic map in which the central visual field (CVF) is highly magnified compared to the peripheral field. Several studies have used functional magnetic resonance imaging (fMRI) in patients with macular degeneration to assess the reorganization of visual processing in relationship with the development of extrafoveal preferred retinal locus (PRL). We evaluated the functional response in PVC and its correlation with retinal parameters in patients with Stargardt disease due to ABCA4 mutations (STGD1).METHODS. Twenty-four STGD1 patients underwent best-corrected visual acuity, full-field standard electroretinogram (ERG), optical coherence tomography, and microperimetry. Furthermore, patients underwent fMRI to assess cerebral activation during visual stimulation by a flickering checkerboard in four PVC subdivisions, corresponding to 0 degrees to 5 degrees (V1), 5 degrees to 10 degrees (V2), 10 degrees to 15 degrees (V3), and 15 degrees to 40 degrees (V4) of CVF.RESULTS. Higher ERG responses were significantly (P < 0.0125) associated with larger functional cerebral response in V1, V2, and V3 subdivisions. Moreover, larger retinal pigment epithelium atrophy area was significantly (P < 0.0125) associated with smaller PVC activation in V2 and V3 subdivisions. Larger activation in V1 subdivision was significantly (P = 0.001) associated with higher mean macular sensitivity and smaller dense scotoma size. Finally, our results showed reduced activation in V2 and V3 with increased PRL eccentricity.CONCLUSIONS. Our study, for the first time in the literature, showed stronger PVC activation in STGD1 patients with a more preserved retinal function and macular structure. Furthermore, our study data strongly suggest that the evaluation of neuronal reorganization could be performed by considering only retinal parameters, particularly ERG responses.