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E. Sato, A. Takahashi, M. Kawai, T. Nagaoka, A. Yoshida; Retinal Hemodynamics in Patients With Normal Tension Glaucoma. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4396.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate whether there are retinal hemodynamic abnormalities in patients with normal tension glaucoma (NTG).
A retinal laser Doppler system (Canon Laser Blood Flowmeter, model CLBF 100, Canon Inc, Tokyo, Japan) was used to measure arterial diameter (D), the time variation of the blood velocity during cardiac cycles, the mean velocity (MV), and the blood flow rate (F) in the major temporal retinal arteries in 15 eyes of 15 patients (age range, 36 to 74 years; mean, 59 years) with NTG, who were newly diagnosed and had not yet taken antiglaucoma agents, and 15 eyes of 15 healthy subjects (age range, 50 to 77 years; mean, 61 years). Additional hemodynamic parameters measured were the peak systolic velocity (PSV), the end diastolic velocity (EDV), the pulsatility ratio [PR=PSV/EDV], the pulsatility index [PI=(PSV-EDV)/MV], and the resistivity index [RI=(PSV-EDV)/PSV], also known as Pourcelot's ratio. The intraocular pressure and blood pressure were measured before the retinal hemodynamics were measured.
There were no differences in intraocular pressure and blood pressure among the groups. All three pulsatility indices (PR, PI, and RI) increased in patients with NTG (4.0±;1.0, 1.25±;0.23, and 0.72±;0.07, respectively) compared with controls (2.90±;0.6, 1.03±;0.30, and 0.62±;0.12, respectively) (unpaired t-test, p<0.05). However, there were no differences in MV, D, or F between the patients with NTG and controls. This suggests that the abnormally increased indices of pulsatility in the retinal arteries of eyes with NTG are not the result of increased distal vascular resistance but rather are likely due to decreased vascular compliance.
Our results indicate that retinal arteries in patients with NTG may develop increased rigidity, and such increased vascular rigidity in these eyes may be partially associated with the cause of the disease.
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