Janine D. Mendola, Suk-tak Chan, Anjali Roy, Ian P. Conner, Terry L. Scwartz, J. Vernon Odom, Kenneth K. Kwong; Loss of visual cortex in children and adults with amblyopia. Journal of Vision 2004;4(8):203. doi: 10.1167/4.8.203.
Amblyopia, sometimes called “lazy eye,” is a relatively common developmental visual deprivation disorder well-characterized behaviorally. However, the neural substrates associated with amblyopia in humans remain unknown. We hypothesized that abnormalities in the cerebral cortex of subjects with amblyopia exist, primarily as a result of experience-dependent neuronal plasticity. Anatomical MRI imaging and psychophysical vision testing was performed on 76 subjects divided into two age ranges (7–12 years) or (18–35 years), and three diagnoses: strabismic amblyopia, anisometropic amblyopia and normal vision. We report a behavioral impairment in high spatial frequency contrast sensitivity for subjects with amblyopia, consistent with previous reports. For all subjects, magnetic resonance imaging (MRI) was used to obtain high-resolution brain images that were analyzed quantitatively with the voxel based morphometry (VBM) module in SPM99. We found that adults and children with amblyopia show decreased gray matter volume in visual cortical regions, including the calcarine sulcus, known to contain primary visual cortex. For the adults with anisometropia, we further found a significant correlation between gray matter volume and performance on the contrast sensitivity test at high spatial frequencies (8 cycles/deg). For the children with amblyopia, additional gray matter reductions in temporal and parietal-occipital areas were detected. These data are the first to provide a specific neuroanatomical basis for the loss of visual sensitivity in human subjects with amblyopia.