Factors Influencing the Optic Nerve Head Blood Flow

Hayreh, Sohan Singh

doi:10.1007/978-3-642-11852-4_5

Cited by 29 publications

(47 citation statements)

References 198 publications

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“…When IOP was raised to 55 mmHg, perfusion pressure (pressure difference between mean arterial blood pressure and IOP) decreased. 9 Cyclic variations in RA diameter with the cardiac cycle, observed visually through the fundus camera eye piece, confirmed that mean flow was decreased at high IOP. We have assumed that the retinal arterial blood velocity drops to 1.0 mm/s at 55 mmHg.…”

Section: Theoretical Development Of Oxygen Diffusion Out Of Rasupporting

confidence: 53%

A simple model of oxygen diffusion out of the retinal artery

Beach

Ning

Khoobehi

et al. 2009

Ophthalmic Technologies XIX

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The purpose of this study is to explore the possibility that oxygen (O 2 ) diffusion out of the retinal artery (RA) can explain the observed significant (P<0.001) decrease of oxygen saturation (O 2 Sat) in RA as intraocular pressure (IOP) is raised from 10 to 55 mmHg. Hyperspectral image data from normal monkeys' optic nerve head (ONH) and overlying retinal blood vessels were recorded at IOP settings of 10, 30, 45 and 55 mmHg. Average percent O 2 Sat values of the RAs were found from the recorded blood spectra by comparing to reference spectra from saturated and desaturated red cell suspensions. Percent O 2 Sat of the RAs was 78.9% at IOP of 10 mmHg. This decreased to 74.1% at 45 mmHg (P=0.01); and further decreased to 51.5% at IOP = 55 mmHg (P<0.0001). To interpret these results, we developed a simple diffusion model assuming that the RA is surrounded by tissues in equilibrium with venous oxygen tension (PO 2 ). O 2 flux across the arterial wall was calculated by Fick's law. The percentage of O 2 diffusing out of the RA were 0.6% at IOP of 10 mmHg, and 38% at IOP of 55 mmHg. Confirmation still requires measurement of blood velocity.

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Section: Theoretical Development Of Oxygen Diffusion Out Of Rasupporting

confidence: 53%

A simple model of oxygen diffusion out of the retinal artery

Beach

Ning

Khoobehi

et al. 2009

Ophthalmic Technologies XIX

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“…In past literature the importance of the vascular factor in the onset and progression of glaucomatous optic neuropathy was emphasized not only for NTG patients (Sugiyama et al, 1995;Cellini et al, 1997;Butt et al, 1997), but also for POAG patients (Flammer, 1994;Hayreh, 1997) and many recent studies have confirmed the validity of that hypothesis (Emre et al, 2005;Flammer et al, 2002;Pache et al, 2002;Galassi et al, 2003;Zink et al, 2003;Fuchsjäger-Mayrl et al, 2004).…”

Section: Discussionmentioning

confidence: 87%

Endothelin-1 plasma levels and vascular endothelial dysfunction in primary open angle glaucoma

et al. 2012

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“…61 Typically, retinal blood flow remains relatively constant over a substantial range of intraocular pressure and systemic blood pressure. 62,63 Compared with the choroidal circulation (a high flow, variable-rate system), the retinal circulation is a more stable, lower flow, constant-rate system supplying a metabolically active tissue. 62 Vascular resistance in the choroid is controlled by the autonomic nervous system.…”

Section: Regulation Of Ocular Blood Flowmentioning

confidence: 99%