Physiology of Perfusion as It Relates to the Optic Nerve Head

Orgül, Selim; Gugleta, Konstantin; Flammer, Josef

doi:10.1016/s0039-6257(99)00009-0

Cited by 80 publications

(77 citation statements)

References 80 publications

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“…38 The overall null association may have been due to the inclusion of SNPs from gene-regulating factors that may affect blood pressure or regulate vascular tone systemically but are not relevant for blood flow regulation, especially to the optic nerve head (ONH). For example, hormones such as epinephrine, vasopressin, and natriuretic peptides [40][41][42] or neurogenic factors 43 are unlikely to affect the regulation of blood flow to the retina and the ONH (e.g., blood vessels in the retina and the ONH are not innervated), 40 whereas intrinsic factors such as vascular endothelial vasoactive agents have an important role in influencing blood flow autoregulation and vascular tone in the ONH. 3,44,45 Of these agents, NO, generated constitutively by eNOS, has a key role in maintaining the basal vasodilator tone in ocular arteries.…”

Section: Discussionmentioning

confidence: 99%

Vascular tone pathway polymorphisms in relation to primary open-angle glaucoma

Kang

Loomis

Yaspan³

et al. 2014

Eye

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Section: Discussionmentioning

confidence: 99%

Vascular tone pathway polymorphisms in relation to primary open-angle glaucoma

Kang

Loomis

Yaspan³

et al. 2014

Eye

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“…6 Several mechanisms of this autoregulation have been previously demonstrated and include metabolic, myogenic, neurogenic, humoral, and endothelial-mediated factors. 7,8 On the other hand, dysfunction of autoregulation has been suggested to be involved in the etiology of glaucoma. [9][10][11][12][13] Glial cells are important components of the eye for maintaining neuronal activity and structural stability.…”

Section: Purposementioning

confidence: 99%

Involvement of Glial Cells in the Autoregulation of Optic Nerve Head Blood Flow in Rabbits

Shibata

Sugiyama²,

Kurimoto³

et al. 2012

Invest. Ophthalmol. Vis. Sci.

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PURPOSE.To investigate the involvement of glial cells in the autoregulation of optic nerve head (ONH) blood flow in response to elevated intraocular pressure (IOP).METHODS. Rabbit eyes were treated with an intravitreal injection of L-2-aminoadipic acid (LAA), a gliotoxic compound. Twenty-four hours after the injection IOP was artificially elevated from a baseline of 20 to 50 or 70 mm Hg and maintained at each IOP level for 30 minutes. ONH blood flow was measured by laser speckle flowgraphy every 10 minutes. Ocular perfusion pressure (OPP) was calculated to investigate the relationship between ONH blood flow and OPP. To evaluate the effects of LAA on the function and morphology of retinal neurons and glial cells, electroretinogram (ERG) was monitored after injections of LAA (2.0 and 6.0 mM) or saline as a control. Histologic and immunohistochemical examinations were then performed.RESULTS. In the LAA-treated eyes, histologic changes selectively occurred in the retinal Müller cells and ONH astrocytes. There was not any significant reduction of amplitude or elongation of implicit time of each parameter in the ERG after LAA injection compared with control. ONH blood flow in LAA-treated eyes was significantly decreased with a reduction of OPP during IOP elevation to 50 and 70 mm Hg, whereas blood flow was maintained in control eyes during IOP elevation to 50 mm Hg. CONCLUSIONS.These results indicate the involvement of glial ells in the autoregulation of ONH blood flow during IOP elevation. (Invest Ophthalmol Vis Sci.

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“…They involve metabolic intermediates such as nitric oxide in the retina, 62 the optic disc, 63 and the brain, 64 prostaglandins, 59,65 and a reduction in intracellular pH in retinal capillary pericytes. 61,66,67 The absence of effect of hypercapnia on ONHBF and ChBF could be related to the species difference regarding tissue-related vasoreactivity (in relationship to the size of vessels), the retinal arterioles being less sensitive to hypercapnia than cerebral arteries, 59,68 and the impact of hypercapnia on the orthosympathic system projecting on the choroid. 69,70 Range of BF Responses to Gas Inhalation Our healthy young subjects showed some heterogeneity in the magnitude of their responses to the changes in the blood gases.…”

Section: Bf Response To Hypercapniamentioning

confidence: 99%

Hypoxic, Hypercapnic, and Hyperoxic Responses of the Optic Nerve Head and Subfoveal Choroid Blood Flow in Healthy Humans

Gallice

Zhou

Aptel

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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Citation: Gallice M, Zhou T, Aptel F, et al. Hypoxic, hypercapnic, and hyperoxic responses of the optic nerve head and subfoveal choroid blood flow in healthy humans. Invest Ophthalmol Vis Sci. 2017;58:5460-5467. DOI:10.1167/iovs.17-21855 PURPOSE. To investigate the impact of different gas mixtures (hyperoxia, hypoxia, and hypercapnia) on the optic nerve head (ONH) and choroidal (Ch) hemodynamics.METHODS. Twenty-three healthy subjects (28 6 6 years) took part in the study. Variations in inspired oxygen and carbon dioxide fraction were produced by a gas mixing device. Arterial oxygen saturation (SpO 2 ) was measured continuously using a transcutaneous sensor and endtidal carbon dioxide partial pressure by capnography. The experiment comprised three successive periods: 3-minute baseline (room air breathing), 15-minute gas mixture inhalation (normocapnic hypoxia, hypercapnia, or hyperoxia), and 15-minute recovery (room air breathing). Laser Doppler flowmeter parameters-velocity (VEL), volume (VOL), and flow (BF) of red blood cells-were measured. Two-way ANOVAs were performed for statistical analysis.RESULTS. In response to hyperoxia, ONHBF significantly decreased by À18% 6 6% (P ¼ 0.04) from baseline, due to significant changes in VEL (À12% 6 3% P ¼ 0.0002). During hypoxia at 85% SpO 2, ONH VEL increased by þ12% 6 3% (P ¼ 0.0009), whereas VOL and BF did not change significantly. ChBF significantly increased by þ7% 6 2% (P ¼ 0.004) in response to hypoxia, due to significant changes in VEL þ5% 6 2% (P ¼ 0.03). Both Ch and ONHBFs did not vary significantly in response to hypercapnia.CONCLUSIONS. The magnitude of the blood flow response is the most significant during hyperoxia for ONH and hypoxia for ChBF. For ONHBF, a 37% difference between hyperoxia and hypoxia can be useful when vasoreactivity to O 2 will be tested in patients.

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Physiology of Perfusion as It Relates to the Optic Nerve Head

Cited by 80 publications

References 80 publications

Vascular tone pathway polymorphisms in relation to primary open-angle glaucoma

Vascular tone pathway polymorphisms in relation to primary open-angle glaucoma

Involvement of Glial Cells in the Autoregulation of Optic Nerve Head Blood Flow in Rabbits

Hypoxic, Hypercapnic, and Hyperoxic Responses of the Optic Nerve Head and Subfoveal Choroid Blood Flow in Healthy Humans

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