| Purpose: To assess the micro-structural white matter integrity of the visual pathway in patients with POAG by using an automated observer-independent tract-based spatial statistics (TBSS) analysis.
Methods: Twenty-five POAG patients and 24 age- and sex- matched healthy controls participated in the study. Tract-based spatial statistics (TBSS) analysis of fractional anisotropy (FA) was used to assess abnormal regions of white matter between two groups. within-group correlation analysis was performed between regions where FA was showed significant different between groups and clinical features for POAG patients.
Results:TBSS analyses showed that POAG patients had significantly reduced FA in the bilateral optic tracts and optic radiations. Further, VOI analysis found that POAG had signi?cantly higher MD in the bilateral optic tracts and optic radiations. In glaucoma group, combined FA values（right plus left）(r=-0.77,p<0.001), combined MD values（right plus left）(r=0.535,p=0.006) for bilateral optic tracts, combined FA values for bilateral optic radiations(r=-0.592,p=0.002) varied consistently with glaucoma stages, while no signi?cant correlation between combined MD values for bilateral optic radiations and glaucoma stages was observed(r=0.209,p=0.316).
Conclusions: POAG is a trans-synaptic neural degenerative disease, and injuries of the optic tract and optic radiation are present in POAG. Diffusion indices derived from DTI, especially the FA value, could be used as objective and effective evaluation indicators for glaucomatous severity. | 
