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Many studies suggest the presence of an IOP-independent pathogenesis in glaucoma because some patients have visual field progression in spite of the apparent adequate IOP reduction. One pathogenesis of glaucoma may be the dysfunction of blood flow. Su et al. (1160) investigated the vascular response in NTG, POAG patients. Casecontrol study design was performed in each 30 patients of NTG, POAG, and normal groups. Endothelium- dependent flow-mediated vasodilation (FMD), one of the indices of vascular response, was measured at the brachial artery. NTG and POAG patients indicated less FMD values compared to the control, which suggest that the dysfunction of peripheral vascular endothelium-dependent vascular response may be ischemia induced neuronal cell death. So far, vascular factors suggesting peripheral blood flow dysfunction such as migraine or Raynaud's disease has been reported in NTG patients. These symptoms are subjective and difficult to evaluate objectively. To this point, it is interesting that FMD can be objectively measured. Still, the number of the subjects in this study is so small that the large scale study should be conducted in future to obtain the strong evidence. Moreover, the relationship between FMD value and the pattern or the progression of visual field defect, the classification of optic disc shape, and various factors as to IOP, should be analyzed to strengthen the role of vascular factors in the pathogenesis of glaucoma.