Altered whole-brain gray matter volume in high myopia patients: a voxel-based morphometry study

High myopia (HM) was associated with impaired long-distance vision. Previous neuroimaging studies showed that abnormal visual experience leads to dysfunction in brain activity in HM even corrected. However, whether alterations in brain structure occur in HM remains unknown. In this study, we analyzed the difference in the whole-brain gray matter volume (GMV) and white matter volume between HM patients and healthy controls (HCs) using a voxel-based morphology method. A total of 82 HM patients (52 men and 30 women) and 58 HCs (28 men and 30 women), matched closely in terms of age and education, were enrolled in this study. All participants underwent MRI scans. The MRI data were processed using the SPM8 software. The relationship between the mean GMV values of the brain regions and clinical features, including refractive diopter and the mean retinal nerve fiber layer thickness, in the HM group were analyzed using Pearson's correlation. Compared with HCs, HM patients showed significantly decreased GMV values in the right cuneus/lingual gyrus and the right thalamus. In contrast, HM groups showed higher GMV values in the brain stem, right parahippocampal gyrus/thalamus, left parahippocampal gyrus/thalamus, as well as the right and the left putamen. No significantly different white matter volume values were found between the two groups. Moreover, in the HM group, the mean retinal nerve fiber layer of the left eye showed a negative correlation with the mean GMV values of the brain stem (r=-0.218; P=0.049), right parahippocampal gyrus/thalamus (r=-0.262; P=0.017), left parahippocampal gyrus/thalamus (r=-0.249; P=0.024), and left putamen (r=-0.232; P=0.036). We found that HM patients showed an altered brain structure in the visual pathway regions and the limbic system, which may provide useful information to explore the neural mechanisms of impaired long-distance vision in HM.