Non-intraocular pressure (IOP) factors such as vascular factors have been identified as contributing to normal tension glaucoma. However, there is not an established range of haemorheological factors considered normal, nor are there standardized tests. In this study, we investigated differences in blood viscosity and haemorheological parameters between patients with normal tension glaucoma (NTG) and normal controls using a new instrument called the BVD-RO1 (BIO-VISCO. Inc., Jeonju, Korea).

Twenty patients with NTG and 20 age-matched normal controls were included in the study. Haemorheological parameters of the venous blood samples, including blood viscosity at the shear rates of 300 (high shear rate) and 1 (low shear rate) s^-1 were measured using an automated scanning capillary tube viscometer.

More hematocrit concentration was detected in the NTG group than in the control group ( p < 0.05). Furthermore, higher blood viscosities at the high ( p < 0.01) and low ( p < 0.01) shear rates were found in the NTG group.

The NTG patients differed in blood viscosity with the control group. This may signify the importance of hemodynamic factors in the pathogenesis of NTG.