Abstract
Abstract: :
Purpose. Little is known about the brain’s response to the loss of visual stimulation due to macular degeneration, as well as changes in brain activity that may follow vision rehabilitation. The aim of the study was to investigate any alterations that may be related to such a reading rehabilitation program. Methods. Three patients (2 AMD–ages 80 and 82 years, 1 Stargardt Disease–44 years), with a mean acuity of 20/225, participated in 8 weeks of rehabilitation using an oculomotor training–for–reading protocol. Patients underwent fMRI (3.0–Tesla) scanning on three occasions: at baseline before training, at 4 weeks, and at 8 weeks following the beginning of training. Three normally sighted control subjects (ages 31, 31, and 76 years) also underwent imaging. The imaging paradigms were designed to assay oculomotor (visually guided saccade task (VGS)), perceptual (illusory contour identification), attention (discrimination of orientation of spatial bars in each of 4 visual field quadrants), and cognitive (word/non–word discrimination task) alterations in neural pathways that reflect rehabilitation outcomes. Results. For the VGS task, the control subjects showed significant activation relative to baseline in the frontal eye fields (FEF), the supplementary eye fields (SEF), the left intraparietal sulcus (IPS), and the precuneus. Both AMD patients showed decreased activity in the inferior FEF after training. The patient with Stargardt disease showed increased activation in the FEF, SEF, and the precuneus following training, and decreased activation in the IPS, and the anterior cingulate gyri (anterior and posterior). For the illusory contours, control subjects activated in V1, V2, V3A, the right IPS, and the left fusiform gyrus. Both AMD patients showed significantly increased activation in V3A, V4, V7, and V8 following training. The patient with Stargardt disease showed decreased activation in V1, V2, and the fusiform gyrus following training. For the attention task, control subjects activated in V1, MT+, FEF, and the IPS. Two patients (1 AMD, 1 Stargardt) showed increased activation in MT+ and the SEF after training, where the remaining patient showed increased activation in V1, V2, V3A, and V4. For the word/non–word task, control subjects activated in the FEF, SEF, IPS, V4, and fusiform gyrus. All 3 patients showed increased activation in the IPS after training. Conclusions. These data demonstrate that changes in brain activation occur after vision rehabilitation.
Keywords: low vision • age–related macular degeneration • retinal degenerations: hereditary