Evaluation of the optic tracts in blind humans by using diffusion tensor magnetic resonance imaging

PURPOSE:The aim of this study was to investigate the optic pathways by using DT-MRI and to expose the differences between congenitaly and acquired blind humans and control groups.MATERIALS and METHODS:Forty one blind patients and twenty six healthy subjects underwent DT-MRI study. The protocol included T2, 3D-SPGR, DWI and DT imaging of the entire brain in the axial plane. Different anisotropy measurements, including ADC, FA, RA were obtained from optic pathways and control localizations and were compared by using student-t test.RESULTS:Bilateral FA and RA values of the lateral geniculate nucleus, in the blind subjects were significantly lower than those of the corresponding anatomic sites in the normal subjects. FA and RA values measured from the optic radiata, Meyer?s loop and control localizations failed to show any statiscally significant difference between those two groups. ADC values of the optic pathways and control localizations in the blind subjects were not significantly different from the values in normal subjects.CONCLUSION:Low FA and RA values measured over the lateral geniculate nucleus indicated a loss of integrity which failed to extend more distally in the optic pathways in blind humans.