Iris Blood Flow Response to Acute Decreases in Ocular Perfusion Pressure: A Laser Doppler Flowmetry Study in Humans

Chamot, Stéphane R.; Movaffaghy, Armand; Petrig, Benno L.; Riva, Charles E.

doi:10.1006/exer.1999.0759

Cited by 16 publications

(5 citation statements)

References 12 publications

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“… 18 This may be due to compromised pupil sphincter upon IOP elevation because iris blood vessels are not autoregulated. 34 , 35 This phenomenon is also seen in patients of acute glaucoma.…”

Section: Discussionmentioning

confidence: 84%

Establishment and Characterization of an Acute Model of Ocular Hypertension by Laser-Induced Occlusion of Episcleral Veins

Zhang

Shi

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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PurposeThis study was designed to develop and characterize a laser-induced model of acute intraocular hypertension that permits the study of the anterior segment of the eye.MethodsCD1 mice aged 5 and 8 weeks were examined for elevation of IOP induced by laser photocoagulation. We compared between occlusion of episcleral veins alone and when combined with 270° limbal vessel occlusion. Anterior chamber angle, corneal thickness, and retinal nerve fiber layer (RNFL) thickness were evaluated by anterior- and posterior-segment optical coherence tomography (OCT). Additionally, at day 7 post-procedure, the anterior segment was evaluated for inflammatory cellular presentation by histologic analysis and OCT, and limbal vessels and whole-mount retina were immunostained for CD31 and Brn3a, respectively. Brn3a-positive retinal ganglion cells (RGCs) were quantified with ImageJ software.ResultsAfter single or combined laser treatment in mice aged 5 or 8 weeks, IOP was significantly elevated for 5 to 6 days before returning to the baseline by day 7 post-procedure. Anterior segment assessment indicated less synechiae in the anterior chamber angle and better preserved limbal vessels with single versus combined laser treatment. Corneal thickness was significantly increased after single or combined treatment. No inflammatory cells were detected in the anterior chamber. The thickness of the RNFL and the density of RGCs were both significantly reduced after single or combined treatment.ConclusionsLaser photocoagulation of episcleral veins alone in CD1 mice aged 5 to 8 weeks may be used to induce ocular hypertension resulting in RNFL thinning and ganglion cell loss. This model permits the study of the anterior as well as the posterior segment of the eye.

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“… 18 This may be due to compromised pupil sphincter upon IOP elevation because iris blood vessels are not autoregulated. 34 , 35 This phenomenon is also seen in patients of acute glaucoma.…”

Section: Discussionmentioning

confidence: 84%

Establishment and Characterization of an Acute Model of Ocular Hypertension by Laser-Induced Occlusion of Episcleral Veins

Zhang

Shi

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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show abstract

“…Iris blood flow has been measured by radioactive labelled microspheres Bill, 1972, 1973;Duijm et al, 1996) and laser Doppler flowmetry (Chamot et al, 2000). Iris blood flow can be modulated by ocular perfusion pressure and drugs (Cole and Rumble, 1970;Kogure, 1982;Nagasubramanian, 1975).…”

Section: Discussionmentioning

confidence: 99%

Quantitative study of the microvasculature and its endothelial cells in the porcine iris

Yang

Cringle

et al. 2015

Experimental Eye Research

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“…It is well known that in some organs (e.g., the brain and retina), a change in perfusion pressure within a certain range does not cause change in blood flow due to the automatic regulation of vascular resistance, i.e., autoregulation, in humans and animals. However, in others, e.g., the iris (animal results) and head skin (human results), autoregulation of blood flow is weak (1,4,6,23). In the second group, an increase in perfusion pressure elicits an increase in blood flow, as shown in the present study.…”

Section: Discussionmentioning

confidence: 99%

Acute hemodynamic responses in the head during microgravity induced by free drop in anesthetized rats

Gotoh

Fujiki

Tanaka

et al. 2004

American Journal of Physiology-Regulatory, Integrative and Comp

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To examine acute hemodynamic responses to microgravity (microG) in the head, we measured carotid artery pressure (CAP) and jugular vein pressure (JVP) to calculate cephalic perfusion pressure (CPP = CAP - JVP) and recorded images of microvessels in the iris to evaluate capillary blood flow velocity (CBFV) and capillary diameter (CD) in anesthetized rats during 4.5 s of microG induced by free drop. Rats were placed in 30 degrees head-up whole body-tilted (HU, n = 7) or horizontal (flat, n = 6) position. In the flat group, none of the measured variables was significantly affected by microG, whereas in the HU group, CAP, JVP, and CPP increased, respectively, by 23.4 +/- 2.6, 1.3 +/- 0.2, and 22.9 +/- 3.1 mmHg, and CBFV and CD increased, respectively, by 33 +/- 8 and 9 +/- 3%, showing an increase in capillary blood flow. To further examine the mechanisms underlying these CAP and JVP increases, another experiment was performed in which CAP and JVP were measured in anesthetized rats (n = 6) during a postural change from HU to flat. In these animals, the change in JVP was similar to that observed during actual microG, but no change in CAP was seen, indicating that the JVP increase during actual microG is caused by disappearance of the gravitational pressure gradient in the head-to-foot axis, whereas the CAP increase is not. In conclusion, actual microG elicits an increase in CPP due to a greater increase in CAP than JVP, resulting in increased capillary blood flow. Although the increase in JVP is explained by the disappearance of gravitational pressure gradient in the head-to-foot axis as a result of microG, the larger increase in CAP is not.

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Iris Blood Flow Response to Acute Decreases in Ocular Perfusion Pressure: A Laser Doppler Flowmetry Study in Humans

Cited by 16 publications

References 12 publications

Establishment and Characterization of an Acute Model of Ocular Hypertension by Laser-Induced Occlusion of Episcleral Veins

Establishment and Characterization of an Acute Model of Ocular Hypertension by Laser-Induced Occlusion of Episcleral Veins

Quantitative study of the microvasculature and its endothelial cells in the porcine iris

Acute hemodynamic responses in the head during microgravity induced by free drop in anesthetized rats

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