Association of Optic Radiation Integrity with Cortical Thickness in Children with Anisometropic Amblyopia

Abstract

Previous studies have indicated regional abnormalities of both gray and white matter in amblyopia. However, alterations of cortical thickness associated with changes in white matter integrity have rarely been reported. In this study, structural magnetic resonance imaging and diffusion tensor imaging (DTI) data were obtained from 15 children with anisometropic amblyopia and 15 age-and gender-matched children with normal sight. Combining DTI and surface-based morphometry, we examined a potential linkage between disrupted white matter integrity and altered cortical thickness. The fractional anisotropy (FA) values in the optic radiations (ORs) of children with anisometropic amblyopia were lower than in controls (P \ 0.05). The cortical thickness in amblyopic children was lower than controls in the following subregions: lingual cortex, lateral occipitotemporal gyrus, cuneus, occipital lobe, inferior parietal lobe, and temporal lobe (P \ 0.05, corrected), but was higher in the calcarine gyrus (P \ 0.05, corrected). Node-by-node correlation analysis of changes in cortical thickness revealed a significant association between a lower FA value in the OR and diminished cortical thickness in the following subregions: medial lingual cortex, lateral occipitotemporal gyrus, lateral, superior, and medial occipital cortex, and lunate cortex. We also found a relationship between changes of cortical thickness and white matter OR integrity in amblyopia. These findings indicate that developmental changes occur simultaneously in the OR and visual cortex in amblyopia, and provide key information on complex damage of brain networks in anisometropic amblyopia. Our results also support the hypothesis that the pathogenesis of anisometropic amblyopia is neurodevelopmental.

Altered cortical morphology of visual cortex in adults with monocular amblyopia

“…Our finding of reduced cortical volume in lateral visual cortex in amblyopic adults is consistent with the prior literature . Several preclinical histological studies and clinical neuroimaging studies have previously reported visual cortex abnormalities in amblyopia . Cortex in the lateral and inferior aspect of the occipital lobe comprises the inferior parts of Brodmann areas 17, 18, and 19.…”

“…This pattern, especially in the visual cortex, given the localized changes in brain volume in this region, may be for the most part established during the sensitive period of visual brain development. Of note, our study revealed similar affected regions as in previous studies of pediatric patients . Thus, there is no indication of a different regional pathology in adults with amblyopia relative to those reported previously in pediatric patients with the disorder.…”

“…Neuroanatomical abnormalities in amblyopia have been confirmed in neuroimaging studies. Atypical features have been described in middle frontal gyrus, parahipopcampal gyrus, fusiform gyrus, inferior temporal gyrus (ITG), calcarine, inferior occipital gyrus, and postcentral gyrus . However, most prior neuroanatomical studies employed voxel‐based morphometry (VBM).…”

“…It uses nonlinear alignment to measure cortical folding patterns and can provide more accurate normalization and measurement of brain anatomy . Studies using SBM demonstrated that children with amblyopia showed reduced cortical thickness in lingual cortex, cuneus, occipital lobe, temporal lobe, and calcarine cortex . While 73–90% amblyopic children have improvements in visual acuity with various treatment modalities, it is generally believed that amblyopia that persists into adulthood is relatively irreversible .…”

Correlation of the measurements of optical coherence tomography and diffuse tension imaging of optic pathways in amblyopia

“…Hess et al demonstrated that functional deficits were first observable at a thalamic level, that of the LGN, and suggested the need to re-evaluate the assumption of a purely cortical dysfunction in amblyopia and the role of LGN in the visual development [26]. Qi et al [27] reported decreased cortical thickness in occipital lobe, lingual gyrus, cuneus, and lunate cortex. There were significant correlations between FA values and cortical alterations in anisometropic amblyopic patients.…”