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Yukiko Maiya, Yukihiro Shiga, Naoko Aizawa, Satoru Tsuda, Yu Yokoyama, Kazuko Omodaka, Tomoki Yasui, Keiichi Kato, Toru Nakazawa; Preperimetric glaucoma pathophysiological study part4: Significant reduction in optic nerve head blood flow. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2752.
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There have been many reports on the role of abnormal ocular blood flow in glaucoma, but its role in pre-perimetric glaucoma (PPG) remains elusive. Here, we measured mean blur rate (MBR)using laser speckle flowgraphy (LSFG) to clarify the association of reduced ocular blood flow with PPG, building on our previous report showing that MBR in the optic nerve head (ONH) tissue could be compared between individuals (Aizawa N et al. Invest Ophthalmol Vis Sci. 2014). In this study, we used LSFG to compare ONH blood flow changes in the eyes of normal subjects and patients with PPG or early normal-tension glaucoma (NTG).
This study comprised 44 normal eyes (54.7 ± 6.9 years old), 62 PPG eyes (54.3 ± 14.3 years old), and 66 early-NTG eyes (55.1 ± 11.4 years old). We performed a standard ophthalmological examination, including optical coherence tomography (OCT), to collect data from these eyes. Then, LSFG was recorded to ascertain changes in ONH blood flow. We determined the ONH tissue MBR and compared the values between the three groups; Kruscal-Wallis test followed by Steel-Dwass test was applied to assess the difference between groups. Multiple regression analysis was carried out on clinical parameters and MBR values to test for association.
The three groups of patients showed no significant differences in age, refractive error, intraocular pressure, or ocular perfusion pressure. However, ONH tissue MBR differed significantly between the normal patients (normal: 13.5 ± 2.6 AU) and the patients with either PPG (11.8 ± 2.4 AU; p = 0.001) or early NTG (11.0 ± 2.2 AU; p < 0.001). Meanwhile, the PPG and early NTG patients did not significantly differ from each other (p = 0.27). Furthermore, multiple regression analysis revealed that ONH tissue MBR was significantly associated with circumpapillary nerve fiber layer thickness, as measured with OCT (standardized partial regression coefficient: 0.29, p < 0.001).
Our results suggest that significant reductions in ONH tissue blood flow are present in eyes with PPG before the development of glaucomatous visual field defects.
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